Nuclear Structure. particle relative charge relative mass proton +1 1 atomic mass unit neutron 0 1 atomic mass unit electron -1 negligible mass
|
|
- Lawrence Hodges
- 7 years ago
- Views:
Transcription
1 Protons, neutrons and electrons Nuclear Structure particle relative charge relative mass proton 1 1 atomic mass unit neutron 0 1 atomic mass unit electron -1 negligible mass Protons and neutrons make up the nucleus, at the centre of the atom, where virtually all the mass of the atom is concentrated. A proton and a neutron have near enough equal mass to one another. Electrons orbit the nucleus in shells of various energies, and have negligible mass. As protons in the nucleus are positively charged, they attract an equal number of electrons into shells surrounding the nucleus. The electronic structure of an atom determines its chemical reactions, so the number of protons determines the chemical identity of an atom. Isotopes Isotopes are atoms that have the same number of protons but a different number of neutrons. Their chemical reactions are the same, and they belong to the same element. Most elements exist naturally as a mixture of isotopes. The mass number is the sum of protons and neutrons in the nucleus The atomic number is the number of protons in the nucleus. So you could say that isotopes are atoms with the same atomic number but different mass numbers. Atomic mass units and relative isotopic mass It would make sense to make one atomic mass unit the mass of something simple, like a 1 H atom, but that would be too obvious! Chemists use one-twelfth the mass of a 12 C atom instead, which if you think about it, amounts to the same thing. As there are six protons and six neutrons in this nucleus, dividing its mass by 12 gives you the mass of a proton or neutron. However, it really is only the mass of a proton or a neutron in 12 C atoms. Protons and neutrons actually have very slightly different masses from one element s nucleus to another. So a proton in a 12 C atom does not have exactly the same mass as one in a 1 H. It very nearly does, but its not quite exactly the same. Don t worry about why! So, relative isotopic mass is the mass of an atom of an individual isotope, relative to one-twelfth the mass of a 12 C atom. In simple terms, relative isotopic mass is how many times more mass an atom has than a single proton or neutron from a 12 C atom. The relative isotopic mass of helium is almost exactly 4 because there are two protons and two neutrons in the nucleus. It is not totally exactly four though because the protons and neutrons in helium nuclei do not have the exact same mass as protons or neutrons in 12 C atoms. Page 1 of 8
2 Relative Atomic Mass and the mole Nuclear Structure As mentioned, most elements exist naturally as a mixture of isotopes. Because the chemical reactions of isotopes are the same, chemists rarely have any interest in separating them. What chemists want to know, is the average mass of an atom, taking the natural abundances of its isotopes into account. This is so they can weigh out an accurate amount of a substance. So, relative atomic mass is the average mass of an atom, taking the natural abundances of its isotopes into account, relative to one-twelfth the mass of a 12 C atom. Chlorine exists naturally as a mixture of 75% 35 Cl and 25% 37 Cl. The average mass of a chlorine atom is 75/100 x 35 25/100 x 37 = One mole of substance is the amount that weighs the same in grams as the relative mass of the substance, e.g. the number of atoms in 12 g of 12 C. The actual number is 6 x 10 23, and this is Avogadro s number. Note that relative atomic masses have no units. For chlorine, 35.5 says that the average chlorine atom has 35.5 times more mass than a proton or neutron in a 12 C atom. However, in reality the RAM or RMM is also the number of grams in one mole of substance. In this case you will learn about molar mass rather than relative masses. The molar mass of chlorine atoms is 35.5 g mol -1, whereas the RAM is simply 35.5 (no units). Atom Amount Mass 1 1 H 6 x atoms 1 gram 4 He 6 x atoms 4 grams 2 12 C 6 x atoms 12 grams 6 35 Cl 6 x atoms 35 grams Cl 6 x atoms 37 grams 17 Remember, chlorine exists naturally as a mixture of 75% 35 Cl and 25% 37 Cl, so: 35 grams of naturally occurring chlorine atoms would be slightly less than one mole 37 grams of naturally occurring chlorine atoms would be slightly more than one mole The average mass of a chlorine atom is 35.5, so if you have 35.5 grams of naturally occurring chlorine atoms, you would have one mole of chlorine atoms. (Ideally, in the calculations above the relative isotopic masses should be used. However, they are so similar to the mass numbers that the mass numbers can be used in their place) Page 2 of 8
3 To summarise: One atomic mass unit is one-twelfth the mass of a 12 C atom. Relative isotopic mass is the mass of an atom of an individual isotope, relative to onetwelfth the mass of a 12 C atom. In RIM the I stands for isotope but you can think of it as I for individual. Relative atomic mass is the average mass of an atom, taking the natural abundances of its isotopes into account, relative to one-twelfth the mass of a 12 C atom. The A in RAM stands for atomic but you can think of it as A for average. One mole is the number of atoms in 12g of 12 C atoms. One mole of any substance has a mass that is equal to the substance s relative mass. Relative Molecular Mass In a molecule, such as CH 3 CH 2 Cl there are atoms present from different elements, in this case carbon, hydrogen and chlorine. In addition, the chlorine atoms occur as a mixture of 35 Cl and 37 Cl, the carbon occurs as 12 C and about 1% 13 C. The hydrogen exists almost entirely as 1 H but there are tiny amounts of both 2 H and 3 H. However, the RAM values for each element already take the different isotopes of each element into account. Element C H Cl RAM (3 s.f.) The RMM of CH 3 CH 2 Cl is therefore 2 x x x 35.5 = 64.5 (no units). The molar mass of CH 3 CH 2 Cl therefore 64.5 g mol -1 So, relative molecular mass is the weighted sum of the individual relative atomic masses of its atoms. In this context the word molecule is used quite loosely. If the compound were MgCl 2 the method is exactly the same, even though MgCl 2 is not a molecular substance, it is ionic and consists of Mg 2 cations and Cl - anion. The RMM of MgCl 2 is x 35.5 = 94.3 (no units) The molar mass of MgCl 2 is 94.3 g mol -1 Sometimes the term formula mass is used to avoid having to remember when to say atomic mass and molecular mass. Page 3 of 8
4 Mass spectrometry of atomic species, such as Ne atoms Neon is a mainly a mixture of 20 Ne and 22 Ne. If such a mixture is injected into a mass spectrometer, the following processes would occur: The atoms are ionised by bombardment with high-energy electrons. This makes them positively charged. 20 Ne e - 20 Ne 2e - 22 Ne e - 22 Ne 2e - The positively charged species are accelerated by attraction towards negatively charged plates. This has the effect of focussing them into a narrow beam and bringing them all up to the same velocity (see diagram later in these notes). The positively charged species are deflected by a magnetic field. Because they are travelling at the same velocity, the ease with which they can be deflected is determined only by their mass to charge ratio. Also, because they are accelerated out of the ionisation chamber as soon as they become positively charged, they are unlikely to have any charge other than 1. Effectively, mass to charge ratio is just the same as mass. The heavier particles need a stronger magnetic field to deflect them into the detector, whereas the lighter particles need a weaker magnetic field to deflect them into the detector. The particles are detected as a small current, because they are charged. A computer counts the number of particles detected per second and plots them against their mass to charge ratio. 20 Ne 9 to 1 ratio of peak heights 22 Ne m/e ratio From the graph, you can calculate the relative atomic mass of Neon to be: 9/10 x 20 1/10 x 22 = 20.2 NB The mass spectrometer is under a high vacuum; otherwise none of the process would be possible! Page 4 of 8
5 Mass spectrometry of diatomic species, such as Cl 2 molecules Chlorine exists as Cl 2 molecules, the atoms are made up of 75% 35 Cl and 25% 37 Cl. 3 to 1 height ratio 35 Cl- 35 Cl 35 Cl- 37 Cl 9 to 6 to 1 height ratio 35 Cl 37 Cl 37 Cl- 37 Cl m/e ratio There are three different types of Cl 2 molecule, each with its own peak in the mass spectrum: The chance of a Cl Cl species existing is 3/4 x 3/4 = 9/16 The chance of a Cl Cl species existing is 3/4 x 1/4 x 2 = 6/16 (there is double the chance because it can be made from a 35 then a 37 or from a 37 then a 35. If you don t get this then don t worry, its really maths, not chemistry) The chance of a Cl Cl species existing is 1/4 x 1/4 = 1/16 Therefore the peaks for the above species exist in a 9:6:1 ratio In addition to these molecular species, some chlorine molecules break down into atoms, so there are two additional peaks for Cl and Cl. Due to the isotopic abundances of Cl atoms, these peaks exist in a 3:1 ratio. Bromine atoms exist as 50% 79 Br and 50% 81 Br, and bromine molecules are also diatomic like those of chlorine. A mass spectrum of bromine is shown below: 1 to 1 height ratio 79 Br- 81 Br 1 to 2 to 1 height ratio 79 Br 81 Br 79 Br- 79 Br 81 Br- 81 Br m/e ratio Page 5 of 8
6 Mass spectrometry of simple molecules, such as CH 3 CH 2 F When the mass spectrum a molecular substance is obtained, some of the molecules break up into fragments that, if charged, can be detected. For example, a mass spectrum of CH 3 CH 2 F is shown below: CH 3 CH 3 CH 2 CH 2 F F CH 3 CH 2 F m/e ratio The peak with the highest mass to charge ratio (furthest to the right) is called the molecular ion or parent ion. Because this peak is the whole molecule, its mass to charge ratio is also the relative molecular mass of the substance. Mass spectrometry is therefore a useful way to quickly find out the RMM of an unknown substance. The different heights of the peaks in the above spectrum are not important, you are not expected to guess at how likely the various fragments are to occur compared to each other. The scheme below shows an example of fragmentation: CH 3 CH 2 F CH 3 CH 2 F CH 3 and CH 2 F, or CH 3 CH 2 F CH 3 CH 2 F CH 3 and CH 2 F For example, if the molecule lost an electron from the C-C bond when bombarded, this would make the bond weak. When it breaks, the remaining electron in it goes either with the CH 2 F fragment, or with the CH 3 fragment. Whichever fragment doesn t get the electron is the fragment that is charged, and therefore the fragment that gets detected by the mass spectrometer. Usually, the electron goes one way some of the time, the other the rest of the time, so usually both fragments are actually detected. Sometimes, the fragmentation occurs in a certain way only, so sometimes only one fragment is detected. This happens if one of the fragments is much more stable, or less stable, than the other. Usually you should assume that the peak furthest to the right gives the RMM. If this is not the case, the question will make it fairly obvious. Page 6 of 8
7 Other points about mass spectrometry When suggesting fragments, you are not allowed to re-combine pieces of the molecule. Only suggest fragments that you could make by breaking up the molecule bit by bit. If you break two bonds to get a fragment, you do not need to put a higher charge on it. Always give structural formula for your fragments, e.g. CH 3 CH 2 O not C 2 H 5 O. C 2 H 5 O could also mean CH 3 OCH 2 for example. Always put a plus charge on anything you suggest for a peak. Nothing can be detected in mass spectrometer without a plus-charge! It is possible, but unlikely, that the molecular ion might be absent altogether from the spectrum. If so, this would be because the entire molecule fragmented, perhaps because the resulting fragments are more stable. This always occurs with polymers, so you cannot use mass spectrometry to measure the RMM of polyethene, for example. Many peaks in a mass spectrum have satellite peaks associated with them with lower mass to charge ratios. This is due to further loss of H atoms from the fragment. Any peak due to a species with carbon atoms in it will also have very low intensity satellite peaks with one unit greater mass to charge ratio. These are due to the small amount of the 13 6 C isotope that is present in naturally occurring carbon. For example, a peak at 15 for a CH 3 fragment might actually look more like as shown below (peak at 16 exaggerated for clarity) Peak at 16 due to 13 CH 3 Peak at 15 due to 12 CH 3 Peak at 14 due to 12 CH 2 Peak at 13 due to 12 CH 15 mass/charge Be able to label a diagram of a mass spectrometer (see next page). If you have enough time, memorise how to draw one as well. Page 7 of 8
8 The mass spectrometer Positive plate Sample in Positive plate Negative plates Electromagn et Hot tungsten filament All under high vacuum Detector Think about the following questions: Why do many samples not need to be heated, even if they are liquids or solids? The apparatus is under a high vacuum, and liquids boil more easily when the external pressure is low. Which parts of the spectrometer cause the particles to become charged? The tungsten filament and positive plate constitute the electron gun and there is a stream of fast moving electrons between them, which knock electrons off the sample atoms. Why to the particles need to become charged? Without a charge they cannot be accelerated, deflected or detected. Why are there small holes in the accelerating negative plates? To focus the moving ions into a narrow beam. Why is there a small hole in the detector? So that the magnetic field can deflect particles with a given mass to charge ratio into the detector. Page 8 of 8
F321 THE STRUCTURE OF ATOMS. ATOMS Atoms consist of a number of fundamental particles, the most important are... in the nucleus of an atom
Atomic Structure F32 TE STRUCTURE OF ATOMS ATOMS Atoms consist of a number of fundamental particles, the most important are... Mass / kg Charge / C Relative mass Relative Charge PROTON NEUTRON ELECTRON
More informationMass Spectrometry. Overview
Mass Spectrometry Overview Mass Spectrometry is an analytic technique that utilizes the degree of deflection of charged particles by a magnetic field to find the relative masses of molecular ions and fragments.2
More informationChapter 1: Moles and equations. Learning outcomes. you should be able to:
Chapter 1: Moles and equations 1 Learning outcomes you should be able to: define and use the terms: relative atomic mass, isotopic mass and formula mass based on the 12 C scale perform calculations, including
More informationElement of same atomic number, but different atomic mass o Example: Hydrogen
Atomic mass: p + = protons; e - = electrons; n 0 = neutrons p + + n 0 = atomic mass o For carbon-12, 6p + + 6n 0 = atomic mass of 12.0 o For chlorine-35, 17p + + 18n 0 = atomic mass of 35.0 atomic mass
More information2 The Structure of Atoms
CHAPTER 4 2 The Structure of Atoms SECTION Atoms KEY IDEAS As you read this section, keep these questions in mind: What do atoms of the same element have in common? What are isotopes? How is an element
More informationAmount of Substance. http://www.avogadro.co.uk/definitions/elemcompmix.htm
Page 1 of 14 Amount of Substance Key terms in this chapter are: Element Compound Mixture Atom Molecule Ion Relative Atomic Mass Avogadro constant Mole Isotope Relative Isotopic Mass Relative Molecular
More informationList the 3 main types of subatomic particles and indicate the mass and electrical charge of each.
Basic Chemistry Why do we study chemistry in a biology course? All living organisms are composed of chemicals. To understand life, we must understand the structure, function, and properties of the chemicals
More informationGetting the most from this book...4 About this book...5
Contents Getting the most from this book...4 About this book....5 Content Guidance Topic 1 Atomic structure and the periodic table...8 Topic 2 Bonding and structure...14 Topic 2A Bonding....14 Topic 2B
More informationCH3 Stoichiometry. The violent chemical reaction of bromine and phosphorus. P.76
CH3 Stoichiometry The violent chemical reaction of bromine and phosphorus. P.76 Contents 3.1 Counting by Weighing 3.2 Atomic Masses 3.3 The Mole 3.4 Molar Mass 3.5 Percent Composition of Compounds 3.6
More information13C NMR Spectroscopy
13 C NMR Spectroscopy Introduction Nuclear magnetic resonance spectroscopy (NMR) is the most powerful tool available for structural determination. A nucleus with an odd number of protons, an odd number
More informationFor convenience, we may consider an atom in two parts: the nucleus and the electrons.
Atomic structure A. Introduction: In 1808, an English scientist called John Dalton proposed an atomic theory based on experimental findings. (1) Elements are made of extremely small particles called atoms.
More informationTest Bank - Chapter 4 Multiple Choice
Test Bank - Chapter 4 The questions in the test bank cover the concepts from the lessons in Chapter 4. Select questions from any of the categories that match the content you covered with students. The
More informationTOPIC 7. CHEMICAL CALCULATIONS I - atomic and formula weights.
TOPIC 7. CHEMICAL CALCULATIONS I - atomic and formula weights. Atomic structure revisited. In Topic 2, atoms were described as ranging from the simplest atom, H, containing a single proton and usually
More informationAtoms, Elements, and the Periodic Table (Chapter 2)
Atoms, Elements, and the Periodic Table (Chapter 2) Atomic Structure 1. Historical View - Dalton's Atomic Theory Based on empirical observations, formulated as Laws of: Conservation of Mass Definite Proportions
More informationMatter. Atomic weight, Molecular weight and Mole
Matter Atomic weight, Molecular weight and Mole Atomic Mass Unit Chemists of the nineteenth century realized that, in order to measure the mass of an atomic particle, it was useless to use the standard
More informationChapter 2: The Chemical Context of Life
Chapter 2: The Chemical Context of Life Name Period This chapter covers the basics that you may have learned in your chemistry class. Whether your teacher goes over this chapter, or assigns it for you
More informationPesticide Analysis by Mass Spectrometry
Pesticide Analysis by Mass Spectrometry Purpose: The purpose of this assignment is to introduce concepts of mass spectrometry (MS) as they pertain to the qualitative and quantitative analysis of organochlorine
More information2 ATOMIC SYSTEMATICS AND NUCLEAR STRUCTURE
2 ATOMIC SYSTEMATICS AND NUCLEAR STRUCTURE In this chapter the principles and systematics of atomic and nuclear physics are summarised briefly, in order to introduce the existence and characteristics of
More information( + and - ) ( - and - ) ( + and + ) Atoms are mostly empty space. = the # of protons in the nucleus. = the # of protons in the nucleus
Atoms are mostly empty space Atomic Structure Two regions of every atom: Nucleus - is made of protons and neutrons - is small and dense Electron cloud -is a region where you might find an electron -is
More informationChemical Calculations: The Mole Concept and Chemical Formulas. AW Atomic weight (mass of the atom of an element) was determined by relative weights.
1 Introduction to Chemistry Atomic Weights (Definitions) Chemical Calculations: The Mole Concept and Chemical Formulas AW Atomic weight (mass of the atom of an element) was determined by relative weights.
More informationElements in the periodic table are indicated by SYMBOLS. To the left of the symbol we find the atomic mass (A) at the upper corner, and the atomic num
. ATOMIC STRUCTURE FUNDAMENTALS LEARNING OBJECTIVES To review the basics concepts of atomic structure that have direct relevance to the fundamental concepts of organic chemistry. This material is essential
More information@ Oxford Fajar Sdn. Bhd. (008974-T) 2012. Matter. 1.1 Atoms and Molecules 1.2 Mole Concept 1.3 Stoichiometry
1 Matter 1.1 Atoms and Molecules 1.2 Mole Concept 1.3 Stoichiometry 2 Chemistry for Matriculation Semester 1 1.1 Atoms and Molecules LEARNING OUTCOMES Describe proton, electron and neutron in terms of
More informationPERIODIC TABLE OF GROUPS OF ELEMENTS Elements can be classified using two different schemes.
1 PERIODIC TABLE OF GROUPS OF ELEMENTS Elements can be classified using two different schemes. Metal Nonmetal Scheme (based on physical properties) Metals - most elements are metals - elements on left
More informationWrite an equation, including state symbols, for the ionisation of indium that requires the minimum energy.(1)
MINI MOCK Questions Unit 1 Atomic Structure AS Chemistry Q1. Indium is in Group 3 in the Periodic Table and exists as a mixture of the isotopes 113 In and 115 In. (a) Use your understanding of the Periodic
More informationTrends of the Periodic Table Diary
Trends of the Periodic Table Diary Trends are patterns of behaviors that atoms on the periodic table of elements follow. Trends hold true most of the time, but there are exceptions, or blips, where the
More informationChapter 2 The Chemical Context of Life
Chapter 2 The Chemical Context of Life Multiple-Choice Questions 1) About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living
More informationAtomic Theory Part 1
Atomic Theory Part 1 Reading: Ch 2 sections 1 6, 8 Homework: Chapter 2: 39, 47, 43, 49, 51*, 53, 55, 57, 71, 73, 77, 99, 103 (optional) * = important homework question The Atomic Theory (John Dalton, 1803)
More informationDetermination of Molecular Structure by MOLECULAR SPECTROSCOPY
Determination of Molecular Structure by MOLEULAR SPETROSOPY hemistry 3 B.Z. Shakhashiri Fall 29 Much of what we know about molecular structure has been learned by observing and analyzing how electromagnetic
More informationChapter 13 Spectroscopy NMR, IR, MS, UV-Vis
Chapter 13 Spectroscopy NMR, IR, MS, UV-Vis Main points of the chapter 1. Hydrogen Nuclear Magnetic Resonance a. Splitting or coupling (what s next to what) b. Chemical shifts (what type is it) c. Integration
More informationIntroduction to Chemistry
1 Copyright ç 1996 Richard Hochstim. All rights reserved. Terms of use. Introduction to Chemistry In Chemistry the word weight is commonly used in place of the more proper term mass. 1.1 Atoms, Ions, and
More informationChapter Five: Atomic Theory and Structure
Chapter Five: Atomic Theory and Structure Evolution of Atomic Theory The ancient Greek scientist Democritus is often credited with developing the idea of the atom Democritus proposed that matter was, on
More informationChapter 3. Mass Relationships in Chemical Reactions
Chapter 3 Mass Relationships in Chemical Reactions This chapter uses the concepts of conservation of mass to assist the student in gaining an understanding of chemical changes. Upon completion of Chapter
More informationCHE334 Identification of an Unknown Compound By NMR/IR/MS
CHE334 Identification of an Unknown Compound By NMR/IR/MS Purpose The object of this experiment is to determine the structure of an unknown compound using IR, 1 H-NMR, 13 C-NMR and Mass spectroscopy. Infrared
More informationChapter 2 Atoms, Ions, and the Periodic Table
Chapter 2 Atoms, Ions, and the Periodic Table 2.1 (a) neutron; (b) law of conservation of mass; (c) proton; (d) main-group element; (e) relative atomic mass; (f) mass number; (g) isotope; (h) cation; (i)
More informationINTI COLLEGE MALAYSIA A? LEVEL PROGRAMME CHM 111: CHEMISTRY MOCK EXAMINATION: DECEMBER 2000 SESSION. 37 74 20 40 60 80 m/e
CHM111(M)/Page 1 of 5 INTI COLLEGE MALAYSIA A? LEVEL PROGRAMME CHM 111: CHEMISTRY MOCK EXAMINATION: DECEMBER 2000 SESSION SECTION A Answer ALL EIGHT questions. (52 marks) 1. The following is the mass spectrum
More informationHow much does a single atom weigh? Different elements weigh different amounts related to what makes them unique.
How much does a single atom weigh? Different elements weigh different amounts related to what makes them unique. What units do we use to define the weight of an atom? amu units of atomic weight. (atomic
More informationChemistry B11 Chapter 4 Chemical reactions
Chemistry B11 Chapter 4 Chemical reactions Chemical reactions are classified into five groups: A + B AB Synthesis reactions (Combination) H + O H O AB A + B Decomposition reactions (Analysis) NaCl Na +Cl
More informationATOMS A T O M S, I S O T O P E S, A N D I O N S. The Academic Support Center @ Daytona State College (Science 120, Page 1 of 39)
ATOMS A T O M S, I S O T O P E S, A N D I O N S The Academic Support Center @ Daytona State College (Science 120, Page 1 of 39) THE ATOM All elements listed on the periodic table are made up of atoms.
More informationSample Exercise 8.1 Magnitudes of Lattice Energies
Sample Exercise 8.1 Magnitudes of Lattice Energies Without consulting Table 8.2, arrange the following ionic compounds in order of increasing lattice energy: NaF, CsI, and CaO. Analyze: From the formulas
More informationMultiple Choice Identify the letter of the choice that best completes the statement or answers the question.
Introduction to Chemistry Exam 2 Practice Problems 1 Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1.Atoms consist principally of what three
More informationHonors Chemistry: Unit 6 Test Stoichiometry PRACTICE TEST ANSWER KEY Page 1. A chemical equation. (C-4.4)
Honors Chemistry: Unit 6 Test Stoichiometry PRACTICE TEST ANSWER KEY Page 1 1. 2. 3. 4. 5. 6. Question What is a symbolic representation of a chemical reaction? What 3 things (values) is a mole of a chemical
More informationChapter 3. Chemical Reactions and Reaction Stoichiometry. Lecture Presentation. James F. Kirby Quinnipiac University Hamden, CT
Lecture Presentation Chapter 3 Chemical Reactions and Reaction James F. Kirby Quinnipiac University Hamden, CT The study of the mass relationships in chemistry Based on the Law of Conservation of Mass
More informationMOLES, MOLECULES, FORMULAS. Part I: What Is a Mole And Why Are Chemists Interested in It?
NAME PARTNERS SECTION DATE_ MOLES, MOLECULES, FORMULAS This activity is designed to introduce a convenient unit used by chemists and to illustrate uses of the unit. Part I: What Is a Mole And Why Are Chemists
More information1. How many hydrogen atoms are in 1.00 g of hydrogen?
MOLES AND CALCULATIONS USING THE MOLE CONCEPT INTRODUCTORY TERMS A. What is an amu? 1.66 x 10-24 g B. We need a conversion to the macroscopic world. 1. How many hydrogen atoms are in 1.00 g of hydrogen?
More informationChemical Calculations: Formula Masses, Moles, and Chemical Equations
Chemical Calculations: Formula Masses, Moles, and Chemical Equations Atomic Mass & Formula Mass Recall from Chapter Three that the average mass of an atom of a given element can be found on the periodic
More informationSYMBOLS, FORMULAS AND MOLAR MASSES
SYMBOLS, FORMULAS AND MOLAR MASSES OBJECTIVES 1. To correctly write and interpret chemical formulas 2. To calculate molecular weights from chemical formulas 3. To calculate moles from grams using chemical
More informationElements, Atoms & Ions
Introductory Chemistry: A Foundation FOURTH EDITION by Steven S. Zumdahl University of Illinois Elements, Atoms & Ions Chapter 4 1 2 Elements Aims: To learn about the relative abundances of the elements,
More informationObjectives. PAM1014 Introduction to Radiation Physics. Constituents of Atoms. Atoms. Atoms. Atoms. Basic Atomic Theory
PAM1014 Introduction to Radiation Physics Basic Atomic Theory Objectives Introduce and Molecules The periodic Table Electronic Energy Levels Atomic excitation & de-excitation Ionisation Molecules Constituents
More informationWoods Chem-1 Lec-02 10-1 Atoms, Ions, Mole (std) Page 1 ATOMIC THEORY, MOLECULES, & IONS
Woods Chem-1 Lec-02 10-1 Atoms, Ions, Mole (std) Page 1 ATOMIC THEORY, MOLECULES, & IONS Proton: A positively charged particle in the nucleus Atomic Number: We differentiate all elements by their number
More information0 10 20 30 40 50 60 70 m/z
Mass spectrum for the ionization of acetone MS of Acetone + Relative Abundance CH 3 H 3 C O + M 15 (loss of methyl) + O H 3 C CH 3 43 58 0 10 20 30 40 50 60 70 m/z It is difficult to identify the ions
More informationThe Mole Notes. There are many ways to or measure things. In Chemistry we also have special ways to count and measure things, one of which is the.
The Mole Notes I. Introduction There are many ways to or measure things. In Chemistry we also have special ways to count and measure things, one of which is the. A. The Mole (mol) Recall that atoms of
More informationChapter Outline. 3 Elements and Compounds. Elements and Atoms. Elements. Elements. Elements 9/4/2013
3 Elements and Compounds Chapter Outline 3.1 Elements A. Distribution of Elements Foundations of College Chemistry, 14 th Ed. Morris Hein and Susan Arena Copyright This reclining Buddha in Thailand is
More informationPROTONS AND ELECTRONS
reflect Imagine that you have a bowl of oranges, bananas, pineapples, berries, pears, and watermelon. How do you identify each piece of fruit? Most likely, you are familiar with the characteristics of
More informationUnit 3 Notepack Chapter 7 Chemical Quantities Qualifier for Test
Unit 3 Notepack Chapter 7 Chemical Quantities Qualifier for Test NAME Section 7.1 The Mole: A Measurement of Matter A. What is a mole? 1. Chemistry is a quantitative science. What does this term mean?
More informationCalculating Atoms, Ions, or Molecules Using Moles
TEKS REVIEW 8B Calculating Atoms, Ions, or Molecules Using Moles TEKS 8B READINESS Use the mole concept to calculate the number of atoms, ions, or molecules in a sample TEKS_TXT of material. Vocabulary
More informationUnit 3 Study Guide: Electron Configuration & The Periodic Table
Name: Teacher s Name: Class: Block: Date: Unit 3 Study Guide: Electron Configuration & The Periodic Table 1. For each of the following elements, state whether the element is radioactive, synthetic or both.
More informationAtoms and Elements. Outline Atoms Orbitals and Energy Levels Periodic Properties Homework
Atoms and the Periodic Table The very hot early universe was a plasma with cationic nuclei separated from negatively charged electrons. Plasmas exist today where the energy of the particles is very high,
More informationAtomic Masses. Chapter 3. Stoichiometry. Chemical Stoichiometry. Mass and Moles of a Substance. Average Atomic Mass
Atomic Masses Chapter 3 Stoichiometry 1 atomic mass unit (amu) = 1/12 of the mass of a 12 C atom so one 12 C atom has a mass of 12 amu (exact number). From mass spectrometry: 13 C/ 12 C = 1.0836129 amu
More informationH 2O gas: molecules are very far apart
Non-Covalent Molecular Forces 2/27/06 3/1/06 How does this reaction occur: H 2 O (liquid) H 2 O (gas)? Add energy H 2O gas: molecules are very far apart H 2O liquid: bonding between molecules Use heat
More informationChapter 4. Chemical Composition. Chapter 4 Topics H 2 S. 4.1 Mole Quantities. The Mole Scale. Molar Mass The Mass of 1 Mole
Chapter 4 Chemical Composition Chapter 4 Topics 1. Mole Quantities 2. Moles, Masses, and Particles 3. Determining Empirical Formulas 4. Chemical Composition of Solutions Copyright The McGraw-Hill Companies,
More informationIntroduction to Nuclear Physics
Introduction to Nuclear Physics 1. Atomic Structure and the Periodic Table According to the Bohr-Rutherford model of the atom, also called the solar system model, the atom consists of a central nucleus
More information19.1 Bonding and Molecules
Most of the matter around you and inside of you is in the form of compounds. For example, your body is about 80 percent water. You learned in the last unit that water, H 2 O, is made up of hydrogen and
More informationAS Chemistry Revision Notes Unit 1 Atomic Structure, Bonding And Periodicity
AS Chemistry Revision Notes Unit Atomic Structure, Bonding And Periodicity Atomic Structure. All atoms have a mass number, A (the number of nucleons), and a proton number, Z (the number of protons). 2.
More informationInstructors Guide: Atoms and Their Isotopes
Instructors Guide: Atoms and Their Isotopes Standards Connections Connections to NSTA Standards for Science Teacher Preparation C.3.a.1 Fundamental structures of atoms and molecules. C.3.b.27 Applications
More informationCHEMISTRY STANDARDS BASED RUBRIC ATOMIC STRUCTURE AND BONDING
CHEMISTRY STANDARDS BASED RUBRIC ATOMIC STRUCTURE AND BONDING Essential Standard: STUDENTS WILL UNDERSTAND THAT THE PROPERTIES OF MATTER AND THEIR INTERACTIONS ARE A CONSEQUENCE OF THE STRUCTURE OF MATTER,
More informationChapter 2 Atoms and Molecules
Chapter 2 Atoms and Molecules 2-1 Elements and their symbols Most of the chemicals you find in everyday life can be broken down into simper substances Key Concepts: A substance that cannot be broken down
More informationWhich substance contains positive ions immersed in a sea of mobile electrons? A) O2(s) B) Cu(s) C) CuO(s) D) SiO2(s)
BONDING MIDTERM REVIEW 7546-1 - Page 1 1) Which substance contains positive ions immersed in a sea of mobile electrons? A) O2(s) B) Cu(s) C) CuO(s) D) SiO2(s) 2) The bond between hydrogen and oxygen in
More informationName Block Date Ch 17 Atomic Nature of Matter Notes Mrs. Peck. atoms- the smallest particle of an element that can be identified with that element
Name Block Date Ch 17 Atomic Nature of Matter Notes Mrs. Peck atoms- the smallest particle of an element that can be identified with that element are the building blocks of matter consists of protons and
More informationChemical Building Blocks: Chapter 3: Elements and Periodic Table
Name: Class: Date: Chemical Building Blocks: Chapter 3: Elements and Periodic Table Study Guide Multiple Choice Identify the letter of the choice that best completes the statement or answers the question.
More information(1) e.g. H hydrogen that has lost 1 electron c. anion - negatively charged atoms that gain electrons 16-2. (1) e.g. HCO 3 bicarbonate anion
GS106 Chemical Bonds and Chemistry of Water c:wou:gs106:sp2002:chem.wpd I. Introduction A. Hierarchy of chemical substances 1. atoms of elements - smallest particles of matter with unique physical and
More informationThe Structure of Water Introductory Lesson
Dana V. Middlemiss Fall 2002 The Structure of Water Introductory Lesson Abstract: This is an introduction to the chemical nature of water and its interactions. In particular, this lesson will explore evaporation,
More informationAbout the course GENERAL CHEMISTRY. Recommended literature: Chemistry: science of the matter. Responsible for the course: Dr.
About the course GENERAL CHEMISTRY University of Pécs Medical School Academic year 2009-2010. Responsible for the course: Dr. Attila AGÓCS Optional course for 2 credit points. To have grade at the and
More informationF321 MOLES. Example If 1 atom has a mass of 1.241 x 10-23 g 1 mole of atoms will have a mass of 1.241 x 10-23 g x 6.02 x 10 23 = 7.
Moles 1 MOLES The mole the standard unit of amount of a substance (mol) the number of particles in a mole is known as Avogadro s constant (N A ) Avogadro s constant has a value of 6.02 x 10 23 mol -1.
More informationelectron does not become part of the compound; one electron goes in but two electrons come out.
Characterization Techniques for Organic Compounds. When we run a reaction in the laboratory or when we isolate a compound from nature, one of our first tasks is to identify the compound that we have obtained.
More information9/13/2013. However, Dalton thought that an atom was just a tiny sphere with no internal parts. This is sometimes referred to as the cannonball model.
John Dalton was an English scientist who lived in the early 1800s. Dalton s atomic theory served as a model for how matter worked. The principles of Dalton s atomic theory are: 1. Elements are made of
More informationIonic and Covalent Bonds
Ionic and Covalent Bonds Ionic Bonds Transfer of Electrons When metals bond with nonmetals, electrons are from the metal to the nonmetal The becomes a cation and the becomes an anion. The between the cation
More information2014 Spring CHEM101 Ch1-2 Review Worksheet Modified by Dr. Cheng-Yu Lai,
Ch1 1) Which of the following underlined items is not an intensive property? A) A chemical reaction requires 3.00 g of oxygen. B) The density of helium at 25 C is 1.64 10-4 g/cm3. C) The melting point
More informationThe melting temperature of carbon
hemical misconceptions 71 The melting temperature of carbon Target level Topics Rationale This exercise is suitable for either 14 16 year olds who have studied bonding and structure and can calculate relative
More informationAtoms, Ions and Molecules The Building Blocks of Matter
Atoms, Ions and Molecules The Building Blocks of Matter Chapter 2 1 Chapter Outline 2.1 The Rutherford Model of Atomic Structure 2.2 Nuclides and Their Symbols 2.3 Navigating the Periodic Table 2.4 The
More informationPROTON NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY (H-NMR)
PROTON NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY (H-NMR) WHAT IS H-NMR SPECTROSCOPY? References: Bruice 14.1, 14.2 Introduction NMR or nuclear magnetic resonance spectroscopy is a technique used to determine
More informationThe Mole. 6.022 x 10 23
The Mole 6.022 x 10 23 Background: atomic masses Look at the atomic masses on the periodic table. What do these represent? E.g. the atomic mass of Carbon is 12.01 (atomic # is 6) We know there are 6 protons
More information3 Atomic Structure 15
3 Atomic Structure 15 3.1 Atoms You need to be familiar with the terms in italics The diameter of the nucleus is approximately 10-15 m and an atom 10-10 m. All matter consists of atoms. An atom can be
More informationMolecular Models in Biology
Molecular Models in Biology Objectives: After this lab a student will be able to: 1) Understand the properties of atoms that give rise to bonds. 2) Understand how and why atoms form ions. 3) Model covalent,
More informationAtomic Calculations. 2.1 Composition of the Atom. number of protons + number of neutrons = mass number
2.1 Composition of the Atom Atomic Calculations number of protons + number of neutrons = mass number number of neutrons = mass number - number of protons number of protons = number of electrons IF positive
More informationSolving Spectroscopy Problems
Solving Spectroscopy Problems The following is a detailed summary on how to solve spectroscopy problems, key terms are highlighted in bold and the definitions are from the illustrated glossary on Dr. Hardinger
More informationProton Nuclear Magnetic Resonance ( 1 H-NMR) Spectroscopy
Proton Nuclear Magnetic Resonance ( 1 H-NMR) Spectroscopy Theory behind NMR: In the late 1940 s, physical chemists originally developed NMR spectroscopy to study different properties of atomic nuclei,
More informationWhat s in a Mole? Molar Mass
LESSON 10 What s in a Mole? Molar Mass OVERVIEW Key Ideas Lesson Type Lab: Groups of 4 Chemists compare moles of substances rather than masses because moles are a way of counting atoms. When considering
More informationMultiple Choice questions (one answer correct)
Mole Concept Multiple Choice questions (one answer correct) (1) Avogadro s number represents the number of atoms in (a) 12g of C 12 (b) 320g of sulphur (c) 32g of oxygen (d) 12.7g of iodine (2) The number
More informationANSWER KEY : BUILD AN ATOM PART I: ATOM SCREEN Build an Atom simulation ( http://phet.colorado.edu/en/simulation/build an atom )
ANSWER KEY : PART I: ATOM SCREEN Build an Atom simulation ( http://phet.colorado.edu/en/simulation/build an atom ) 1. Explore the Build an Atom simulation with your group. As you explore, talk about what
More informationAS1 MOLES. oxygen molecules have the formula O 2 the relative mass will be 2 x 16 = 32 so the molar mass will be 32g mol -1
Moles 1 MOLES The mole the standard unit of amount of a substance the number of particles in a mole is known as Avogadro s constant (L) Avogadro s constant has a value of 6.023 x 10 23 mol -1. Example
More informationAtomic Theory: History of the Atom
Atomic Theory: History of the Atom Atomic Theory: experimental observations that led scientists to postulate the existence of the atom (smallest bit of an element). 1. Law of Conservation of Mass -During
More informationThe Mole Concept. The Mole. Masses of molecules
The Mole Concept Ron Robertson r2 c:\files\courses\1110-20\2010 final slides for web\mole concept.docx The Mole The mole is a unit of measurement equal to 6.022 x 10 23 things (to 4 sf) just like there
More informationneutrons are present?
AP Chem Summer Assignment Worksheet #1 Atomic Structure 1. a) For the ion 39 K +, state how many electrons, how many protons, and how many 19 neutrons are present? b) Which of these particles has the smallest
More informationThe Mole Concept and Atoms
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 4 24 September 2013 Calculations and the Chemical Equation The Mole Concept and Atoms Atoms are exceedingly
More informationSample Exercise 8.1 Magnitudes of Lattice Energies
Sample Exercise 8.1 Magnitudes of Lattice Energies Without consulting Table 8.2, arrange the ionic compounds NaF, CsI, and CaO in order of increasing lattice energy. Analyze From the formulas for three
More informationCHAPTER 6 Chemical Bonding
CHAPTER 6 Chemical Bonding SECTION 1 Introduction to Chemical Bonding OBJECTIVES 1. Define Chemical bond. 2. Explain why most atoms form chemical bonds. 3. Describe ionic and covalent bonding.. 4. Explain
More informationChemistry Diagnostic Questions
Chemistry Diagnostic Questions Answer these 40 multiple choice questions and then check your answers, located at the end of this document. If you correctly answered less than 25 questions, you need to
More informationStoichiometry. What is the atomic mass for carbon? For zinc?
Stoichiometry Atomic Mass (atomic weight) Atoms are so small, it is difficult to discuss how much they weigh in grams We use atomic mass units an atomic mass unit (AMU) is one twelfth the mass of the catbon-12
More information7.4. Using the Bohr Theory KNOW? Using the Bohr Theory to Describe Atoms and Ions
7.4 Using the Bohr Theory LEARNING TIP Models such as Figures 1 to 4, on pages 218 and 219, help you visualize scientific explanations. As you examine Figures 1 to 4, look back and forth between the diagrams
More informationCandidate Style Answer
Candidate Style Answer Chemistry A Unit F321 Atoms, Bonds and Groups High banded response This Support Material booklet is designed to accompany the OCR GCE Chemistry A Specimen Paper F321 for teaching
More information