Electrons and the Periodic Table Mrs. Freeman

History HOW WAS MENDELEEV’S PERIODIC TABLE ARRANGED? By their chemical properties  HOW IS THE MODERN PERIODIC TABLE ARRANGED? By increasing number of protons and atomic mass. WHY DIDN’T MENDELEEV ARRANGE HIS TABLE THIS WAY? Because at the time the number of protons was not known.

PERIODS: are a horizontal row of elements. HOW MANY: 7 VARIATION ACROSS A PERIOD: Changes from metals to metalloids to nonmetals

GROUPS AKA FAMILIES: the individual columns of elements. HOW MANY? 18 SIMILARITIES BETWEEN ELEMENTS IN THE SAME GROUP? They have the same number of valence electrons

THREE CLASSES OR CATEGORIES OF ELEMENTS ON THE PERIODIC TABLE METALS NONMETALS METALLOIDS LOCATION Left side of the stair step line Right side of the stair step line Along the stair step line EXAMPLES AND USES Zinc-vitamins and certain containers. Potassium-in bananas for cells to use Oxygen-gas to breathe Carbon-foundation for life. Aluminum- cans, canisters, cars. Silicon-sealant against water PROPERTIES Hard, malleable, durable, rust, dense Not dense, colorless, Has properties of both metals and non-metals.

REACTIVITY PATTERN WITHIN A GROUP: increasing reactivity, decreasing melting and boiling point and density generally increases, Metals Left side of the table Nonmetals Right side of the table

1 2 13 14 15 16 17 18 3 4 5 6 7 8 ALKALI METALS ALKALINE EARTH METALS BORON FAMILY CARBON FAMILY NITROGEN FAMILY OXYGEN FAMILY HALOGENS NOBLE GASES GROUP # 1 2 13 14 15 16 17 18 LIST OF ELEMENTS IN GROUP Hydrogen Lithium Sodium Potassium Rubidium Cesium Francium Beryllium Magnesium Calcium Strontium Barium Radium Boron Aluminum Gallium Indium Thallium Carbon Silicon Germanium Tin Lead Nitrogen Phosphorus Arsenic Antimony Bismuth Oxygen Sulfur Selenium Tellurium Polonium Fluorine Chlorine Bromine Iodine Astatine Helium Neon Argon Krypton Xenon Radon # of valence electrons 3 4 5 6 7 8 Key Facts Prop. And Reactivity Uses Are very reactive. Form Ionic Compounds Metal Ex. Salt React with halogens well. Form ionic compounds. Ex. Magnesium chloride Forms covalent compounds Non-metals Boron is metalloid. Forms both covalent and ionic bonds. 2 metals and 2 metalloids Forms covalent bonds. Basis for fertilizer Forms covalent and ionic bonds. Most abundant elements in earths crust. All are non-metals. Most reactive group. Inert-do not react

THE MOST REACTIVE METALS: Francium, Cesium, and Rubidium (in order from most reactive to least reactive) THE MOST REACTIVE NONMETALS: Fluorine, Chlorine, and Bromine (in order from most reactive to least reactive)

Excited electron- an electron in an energy level higher than its ground state (it has absorbed energy)

Ground state- all the electrons have the lowest possible energy.

Energy Level- The possible energies that electrons in an atom can have.

Sub-level Electron orbital designated s, p, d or f. These sublevels or orbitals have characteristic shapes which can be used to explain and predict the chemical bonds that atoms can form.

Orbital- the region of space around the nucleus where an electron is likely to be found.

Energy level/energy shell- the possible energies that electrons in an atom can have.

Three ways to show arrangements of electrons Orbital Configuration Notation Electron Configuration Notation Electron Dot Notation

Electron configuration- specific distribution of electrons in atomic orbitals of atoms or ions.

Valence shell- the outside energy shell

Valence electrons- an electron that is in the highest energy level of an atom.

Orbital Configuration Notation each electron is assigned a space with an up spin or a down spin. All up spins must be placed first. Then place all down spins until all electrons are used.

Electron configuration notation: is just the letters and numbers from the orbital configuration. Example: Ar= 1s2 2s2 2p6 3s2 3p6

Electron dot notation: the valence electrons represented by dots around the element symbol. -fill in using the house memory trick

Hund’s Rule every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.

Aufbau Principle: is used to determine the electron configuration of an atom, molecule or ion. The principle postulates a hypothetical process in which an atom is "built up" by progressively adding electrons.

Pauli’s Exclusion Principal “no two electrons in the same atom can be in the same quantum state.” [1] This means that no two electrons can have the same set of quantum states of: 1) energy, 2) angular momentum magnitude, 3) angular momentum orientation, and 4) orientation of intrinsic spin.

Assessment LIST THE PERIOD TO WHICH EACH OF THE FOLLOWING BELONGS: STRONTIUM: 5 IRON: 4 RADON: 6 ANTIMONY: HOW MANY ELEMENTS ARE IN PERIOD 4? 18 HOW MANY ELEMENTS ARE IN PERIOD 6? 32

Assessment: NAME THE ELEMENT IN GROUP 3 PERIOD 4 Scandium. HOW MANY VALENCE ELECTRONS ARE IN AN ATOM OF FLUORINE? 7 TO WHAT GROUP DOES CARBON BELONG 14