Atoms And The Periodic Table

Atoms And The Periodic Table

Atomic Structure

Element matter that is composed of one type of atom Elements are abbreviated in scientific shorthand either a letter or a pair of letters called chemical symbol. Ex: Aluminum Al Copper Cu Atom smallest piece of matter that still has the properties of the element.

Protons positive charge (1 + ) Neutrons neutral or no charge Electrons negative charge (1 - ) Nucleus located in center of atom consists of protons and neutrons; electrons surround the nucleus

Electron Cloud (current) model which shows electrons travelling in specific energy levels around a nucleus; electrons closest to nucleus have low energy, electrons farther away have high energy. Electrons in Energy Levels Energy Level in Atom Energy Level in Atom 1 2 2 8 3 18 4 32 * Last energy level can only hold max of 8 electrons H and He are exceptions

Masses of Atoms

Smaller particles of matter called quarks exist but scientists still consider atoms to be the basic building blocks of matter Quark smaller particles that make up protons and neutrons six quarks are to exist Atomic mass composed mostly of protons and neutrons in the nucleus also called mass number

Atomic number the number of protons in an atom; number of protons also identifies the element * If you needed to find # of neutrons of an atom: # of Neutrons = mass number atomic number

Element from the Periodic Table Atomic Number: Number of protons and it is also the number of electrons in an atom of an element. Element s Symbol: An abbreviation for the element. 8 O Elements Name Atomic Mass/Weight: Number of protons + neutrons. Oxygen 16

Components of the Atom Protons have a mass of 1 amu (atomic mass unit). Neutrons have a mass of 1 amu. Electrons have very little to almost NO mass. The nucleus is very small and DENSE, however, the atom is mostly EMPTY space

Atoms Are Neutral Atoms have no overall charge. This is because atoms have an EQUAL number of protons and electrons. Equal number of (+) and (-) charge; they cancel any positive or negative charges out. Electron + Proton = Neutral (+ ) + (-) = 0 (A NEUTRON HAS NO CHARGE SO IT DOES NOT EVER ALTER THE CHARGE OF THE ATOM)

If an atom GAINS or LOSES electrons it become a: Negative Ion or Positive Ion

Isotopes atoms of the same element that have different number of neutrons. B 10 (Boron 10) or B 11 (Boron 11) Different isotopes have different properties. Average atomic mass weighted average mass of an elements isotopes.

IONS Ions are substances made up of charged atoms/particles (could be positive or negative). Most substances are ionic or have a specific charge Examples of ions: Salt, Orange Juice, Vinegar, Drain Cleaner, Toothpaste, etc.

Common Mass Numbers Element Symbol Atomic No. Protons Neutron s Mass No. Ave. Atomic Mass BORON B 5 5 6 11 10.81 amu CARBON OXYGEN SODIUM COPPER C 6 6 6 12 12.01 amu O 8 8 8 16 16 amu Na 11 11 12 23 22.99 amu Cu 29 29 34 63 63.55 amu Nitty Gritty Science, LLC 2016

The Periodic Table

Periodic Table Table where elements are organized by increasing atomic number (number of protons). Dmitri Mendeleev (1800s) created first periodic table based on atomic mass. Henry Moseley arranged elements by atomic number (what we use today.)

- The periodic table is arranged by groups and periods Groups Vertical columns of elements with similar properties - groups are numbered 1-18. - Elements in the Same GROUP are most chemically similar / have similar properties.

Elements in the same group have same number of valence electrons in their outer energy level ( 1 s place) - EXCEPT TRANSITION METALS (ENTIRE MIDDLE SECTION Groups # 3-12) * These elements have different numbers of valence electrons and do not follow the same rules as the rest of the table. Ex: Group 13 has 3 valence electrons, group 18 has 8, etc.

Periods Horizontal ROWS of elements. Periods are numbered 1-7 Elements in the same period have the same number of energy shells / orbitals in common. Ex: H & He are in 1 st pd they both have 1 energy shell.

Metals Good conductors of heat and electricity, ALL but mercury are SOLID at room temperature * Metals are located on the left side of the period table. Pd table is mostly Metals. Metalloids Elements that make up stair step; have properties of both metals and non-metals. Nonmetals Elements that are usually GASES or brittle solids at room temperature; located on the right of the table.

Electron Dot Diagram Uses the element symbol and dots to represent outer energy level electrons only (valence). Use pd table to assist you in creating these. (Groups) - Begin dots at the top and continue in the clockwise direction. MAXIMUM of 8 VALENCE E s. He O Ne Al

Metals good conductor of heat and electricity, all but mercury are solid at room temperature * Metals are located to the left of stair step Alkali Metals (Group 1) are the most reactive of all metals; don t occur in nature in their element form Alkaline Earth Metals (Group 2) shiny, ductile and malleable; combine readily with other elements

Transition Elements (Group 3 12) most familiar metals because they often occur in nature uncombined Inner Transition Metals (listed below table) Lanthanide Series elements with atomic # 58 71 Actinide Series elements with atomic # 90 103 Nonmetals elements that are usually gases or brittle solids at room temperature; most can form ionic and covalent compounds located to the right of the stair step.

Noble gases (Group 18) exist as isolated atoms. They are all stable because outer energy level is filled Metalloids elements that make up stair step; have me have metallic and non-metallic properties Metalloids are part of the mixed groups which contain metals, nonmetals and metalloids (mixed groups are Group 13, 14, 15, 16, 17)