Grade 9 Science Unit: Atoms and Elements Topic 4: Periodic Table & Compounds

Transcription

1 Grade 9 Science Unit: Atoms and Elements Topic 4: Periodic Table & Compounds Topic Using the Periodic Table Metals, Non- Metals & Metalloids I can Explain and identify the periods of the Periodic Table. Explain and identify the groups or families of the Periodic Table. Identify Elements by their symbol and their name. State the Atomic Number, Mass Number and Atomic Mass for any element, given the Periodic Table. State how many protons, neutrons and electrons are in an element, given the Periodic Table. Explain what an isotope is. State the Atomic Mass, Mass Number, Number of Neutrons, Protons and Electrons for an isotope of an element. Explain how an ion is formed. State the ion charge of an element, given the Periodic Table. Identify Metals on the Periodic Table. State the physical properties of most metals. State the chemical properties of most metals. Identify Non-Metals on the Periodic Table. State the physical properties of most non-metals. State the chemical properties of most non-metals. Identify Metalloids on the Periodic Table.

2 State the physical properties of most metalloids. State the chemical properties of most metalloids. Element Families Identify the Alkali Metals; explain their similarities and differences. Identify the Alkaline-Earth Metals; explain their similarities and differences. Identify the Halogens; explain their similarities and differences. Identify the Noble Gases; explain their similarities and differences. Classification of Matter Distinguish between Pure Substances and Mixtures; give examples of both. Distinguish between Compounds and Elements; give examples of both. Distinguish between Homogeneous Mixtures and Heterogeneous Mixtures; give examples of both. Explain how a solid solution can exist and give an example of a solid solution. Types of Explain the properties of Ionic Compounds. Compounds Explain how the atoms are bonded in Ionic Compounds. State which types of atoms create Ionic Compounds. Explain the properties of Molecular Compounds. Explain how the atoms are bonded in Molecular Compounds. State which types of atoms create Molecular Compounds. Explain what atoms create Diatomic Molecules. Compound State any elements are in a compound, given the symbolic formula. Symbols State the quantity of elements within a compound, given the symbolic formula. Sketch a rough diagram of each compound. Explain how no atoms are lost in a chemical change; that the mass and the atoms balance going into a reaction and coming out of a reaction.

3 4.1 - Using the Periodic Table knew that some elements were very similar, and it made sense to him to group them together. For example, he grouped together,, and other metals that reacted violently with. In 1886, the element was discovered. This element had the exact properties of a on Mendeleev s table. rearranged the elements to the table we have now based on the of the elements. Label the following onto the blank periodic table: - Periods, groups - Solid, liquid, gas - Metal, metalloid, non-metal - Alkali Metals, Alkaline Earth metals, Halogens, Nobel Gases, Transitional Metals

4 Use the Sask. Science 9 (pg ) to complete the notes below: Period - row of elements in the periodic table - They are numbered from to - The most metals start on the, as you move the metals become less reactive Group/Family - column of elements in the periodic table - They are numbered from to - Elements in the same group have Element Symbol & Name (Pg ) - Element symbols are used to describe elements because and it will make - An element symbol consists of or letters - The letter is capitalized, and if there is a second letter it is - The rule about capitalization is very important. Ex. The symbol stands for, while represents (a compound that contains both and ) - The symbol is sometimes an of the elements English name, other times it abbreviates the elements name. Ex/ the symbol for Silicone is where as the symbol for Silver is because its Latin name is. - Some elements are named based on where they were discovered, like which was discovered at the University of California. - is a strong yet light metal element. It is named for the, powerful gods of Greek mythology. Atomic Number - The atomic number is typically found of each element square - It shows how many are in one atom of that element. - Atoms have a charge, therefore the number of equals the number of - As you move across the periodic table from left to right the atomic number by

5 Ex/ Nickel s atomic number is, therefore it has protons and electrons Atomic Mass - Typically found the elements name in each element square - Atomic mass is always expressed as a, because each element, except for, can form, which are atoms with different numbers of - in them and therefore different. - Atomic mass is the average of all an element s different - Mass is measured in (amu) - Hydrogen has an atomic mass of and iron has an atomic mass of. This means that iron is times heavier than hydrogen atoms. Mass Number The mass number of an element is the atomic number rounded to a whole number - Is the total number of and in an atom - are too small, therefore they have very little effect on the total mass of the atom - To determine the number of neutrons an element has subtract the from the - = Isotopes - A form of an atom that has a different number of than the common form of that atom - Ex. The most common form of hydrogen has proton and electron but neutrons. A small percentage of hydrogen atoms have proton, electron, and neutron. An even smaller percentage of hydrogen atoms have proton, electron and neutrons. - The most common form of carbon contains protons and neutrons, therefore has a mass number of. Carbon-14 is an isotope of carbon that has a mass number of 14. Because it isn t the most common form of carbon, its mass number is indicated with -14 at the end of the element name. Carbon-14 is used for

6 Ion Charge - Ions are formed when atoms or groups of atoms or electrons. - Ion charge is the charge that an atom takes on when it loses or gains electrons. - Elements that gain electrons become charged, whereas elements that lose electrons become charged. - Elements with atoms that form similar are grouped together in the periodic table. For example, elements in the first column on the left side of the periodic table all form ions of ion charge.

7 Complete the table below: Element Element Atomic Atomic Mass Ion # of # of # of Name Symbol Number Mass Number Charge Protons electrons neutrons Hydrogen Bromine 81 Iron Titanium-46 Lead Uranium-235 Vanadium Phosphorus Argon Magnesium Uranium Carbon Helium Assignment: Complete Chart above and complete questions from Saskatchewan Science 9 page 188#3, 4, 8.

8 4.2 Metals, Non-metals, Metalloids Metals - Metals are found of the side of the periodic table Physical Properties o Most are and o Excellent conductors of and o They are also and o Most metals are at room temperature. is a metal that is at room temperature. Chemical Properties o Some metals react explosively with (Ex. ) o Others will not react even if mixed with (Ex. ) Non Metals - Only of the known elements are classified by scientists as non-metals. - These elements are not grouped because of their similarities but because - Non-Metals are found of the side of the periodic table Physical Properties - of the non-metals are gases at room temperature, are solid, and is liquid. - Solid non-metals do not conduct or. - Solid non-metals are and not elements - Solid non-metals have little or no Chemical Properties - Some non-metals are very reactive. - is a Yellow solid. It is a very reactive gas and will in air. It will melt into a liquid with heat. - Pure is very and. Metalloids - Have both and properties - They are often used in, such as Physical Properties - Metalloids electricity but, they are called

9 - is the most common metalloid. It is and, but unlike a metal, it is. About 40% of the mass of any comes from silicon. It is also a major component in Assignment: complete questions from Saskatchewan Science 9 page 165 #1, 3, 6, Element Families Alkali Metals - Group elements. Similarities - in colour. - Like other metals, they are and ; they conduct and. - Unlike other metals, they have melting points and melt below - These are the metals. - These metals react when exposed to or Differences - From top to bottom, increases, and decreases. Alkaline-Earth Metals - Group elements - in colour. - These elements also react when exposed to or, however their reactivity is not as as alkali metals - They are and have a than sodium and potassium - Alkaline-Earth Metals have melting points that alkali metals Halogens - Group elements Similarities - Each has a but colour. - They all have a low point - They are the most non-metals Differences - Moving from top to bottom, the colours of the vapours grow in - Also, melting points

10 Noble Gases - Group elements Similarities - All exist naturally as gases, but will glow with bright colours if - They are the most elements Differences - From top to bottom, the increases Assignment: complete questions from Saskatchewan Science 9 page 184 #1-3.

11 4.4 - Classification of matter All - Contain only one type of particle - can exist in three : solid, liquid and gas - contain two or more pure substances - Examples: water, salt, sugar - Examples: iron, gold, oxygen (Solutions) - appear to be one substance - particles of different substances are intermingled - examples: vinegar, clear air (Mechanical Mixtures) - two ore more parts can be seen - different kinds of particles stay together - examples: soil, blood, concrete Identify each mixture as homogeneous or heterogeneous. Dirt Sterling silver bracelet Sample of pond water Recycled paper Answer each question with a full sentence. To the unaided eye, a mixture appears to be a white liquid with no visible substances floating around. Can this mixture be classified as homogeneous? Explain why or why not.

12 Air can be classified as heterogeneous or homogeneous. Explain why this statement is true. Read the descriptions below. In the space provided, indicate whether each mixture is a mechanical mixture (MM) or a solution (S) The different substances in this mixture can be distinguished from each other with the unaided eye or a magnifying glass The substances in this mixture cannot be separated by filtering When this mixture is left to stand undisturbed, the substances do not separate by floating to the top or settling to the bottom. This mixture appears cloudy or opaque. You cannot see through it clearly. Combining Metals (Pg 159) Some metals, such as and, are too to be used alone for some purposes. Therefore, to make a substance stronger, some metals are often melted and mixed with other melted metal elements. The mixture is cooled to become a solid. A solution of two or more metals is called an. Common alloys include a combination of and or, this is often called because it has a lighter colour than pure gold. White gold is often used in engagement rings and wedding bands to give them and. Alloys are used in,, and many other household items. Assignment: complete questions from Saskatchewan Science 9 page 127 #2-4, 7 and page 146 #3, 15.

13 4.5 Types of Compounds Ionic Compounds Properties - Ionic compounds have melting points (they are solid at room temperature) - When dissolved in water, they are good - They all form How they are formed - Ionic compounds are pure substances formed as a result of the attraction between ions of opposite charges - atoms tend to lose electrons, therefore they become ions. Whereas, atoms tend to gain electrons, therefore they become ions. - Ex) When combines with, an electron from the highest energy level of a sodium atom moves to the outer level of the chlorine atoms. This causes the atoms to become. Molecular Compounds - Composed of 2 - May be, or at room temperature - Tend to be or poor conductors of electricity - They have relatively melting and boiling points due to the weak forces between molecules - In a molecular compound, atoms join together by electrons in the highest energy level Diatomic Molecules - Molecules composed only of are. Common diatomic molecules are,,,,,,, and. Assignment: complete questions from Saskatchewan Science 9 page 173 #1-4, 9.

14 4.6 Compound Symbols Physical State of Compounds - Commonly a chemicals state will be indicated behind the element compound as a subscript, solid, liquid, gas, aqueous (dissolved in water) Symbols - The symbol of each that is contained in a compound will be written in the of that compound Ex/ NaCl ***Remember there are 1 or 2 letters in each compound symbol and the first letter is capitalized, the second is lowercase Therefore the two symbols in NaCl are Na and Cl, which means that and are contained in NaCl - There are sometimes behind a chemical symbol, these numbers show how many of each chemical are in the compound. Ex/ H 2 O 2 Hydrogen and 1 Oxygen molecule

15 Complete the table below Compound CaO Element in compound Molecular or Ionic Number of Atoms in Each Element Drawing of Compound CaCl 2 Al 2 O 3 Na 2 O AlCl 3 NaOH Chemical Formula - Matter cannot be. - In, both sides must contain the same number of atoms of each. - in front of a compound indicate how many of the compound are used in the. Ex/ 2CH 3 OH + 3O 2-2CO H 2 O In CH 3 OH, there is carbon, Hydrogen, and Oxygen and in O 2 there are oxygen. The formula uses of CH 3 OH molecules and 3, therefore on the left side of the formula 2 Carbon 8 Hydrogen 8 Oxygen On the left side of the equation, there are 2 molecules of CO 2 and 4 molecules of H 2 O. Therefore there are: 2 Carbon 8 Hydrogen 8 Oxygen - In addition to matter being conserved, the is also conserved. Ex/ Mg + S MgS 24.3g 32.1g 56.4 Assignment: complete questions from Saskatchewan Science 9 page 173 #7, 11.