You Already Know That… Noble gases are the least reactive Alkali metals & halogens are the most reactive All elements want to follow the octet rule This states that elements want full s & p orbitals, or 8 valence electrons, except H, which only wants 2

You Also Know That… Ions are charged atoms Cations are atoms with positive charges They are usually on the left side of the periodic table. Anions are atoms with negative charges They are usually on the right side of the periodic table.

Stable Ions Some ions have Noble Gas Configurations, or complete octets They only give up a certain number of electrons Ca will give up it’s 2 valence electrons becoming Ca2+ which has 8 valence electrons

Stable Ions (cont.) Some do not have complete outer shells They are the transition elements & a few other metals Most can give up different amounts of electrons Fe can give up 2, 3 or 4 electrons becoming Fe2+, Fe3+ or Fe4+

Connections Elements follow the easiest path by removing, or gaining, the least amount of electrons It’s easier for Ca to remove 2 electrons than to gain 6 electrons Ions have different properties than their parent elements since electrons determine properties

Types of Ions Monoatomic Ions form from one atom Ca2+ N3- Fe4+ O2- K+ Cl- Polyatomic Ions are formed from 2 or more bonded atoms NO3- NH4+ CN- CrO42-

Ionic Bonding Ions combine to create salts with a crystal lattice structure Tightly-packed bonded atoms They are brittle, have high melting & boiling points, and are good conductors of electricity when dissolved in water

Ionic Bonding Ions with different charges bond together to form compounds A cation will bond with an anion Charges must cancel out when bonded Ca2+ & N3- cancel out by there being 2 N3- & 3 Ca2+ to make Ca3N2 Criss-Cross Method: the charge of one ion becomes the subscript of the other

Naming Compounds Binary compounds, compounds with just 2 elements, combine monoatomic cations and anions A compound is named by combining the names of its ions Ca2+ is “calcium” & N3- is “nitride” So Ca3N2 is called “calcium nitride”

Writing Formulas When starting with a compound's name, break it apart and write the separate ions Sodium Chloride is composed of a sodium (Na+) and a chloride, or chlorine anion (Cl- ) Then combine the two ions Na+ + Cl- is NaCl

Writing Names When starting with a polyatomic compound's formulas break it apart and write the separate ions (NH4)3PO4 is composed of an NH4+ (ammonium) and a PO4-3 (phosphate) Then combine the two names Ammonium Phosphate

Covalent (Molecular) Compounds When 2 non-metals combine, they use prefixes to tell their amount If there is only one of the first element, you DO NOT use mono- Mono = 1 Di- = 2 Tri- = 3 Tetra- = 4 Penta- = 5 Hexa- = 6 Hepta- = 7 Octa- = 8 Nona- = 9 Deca- = 10

Naming Acids Ion Name Acid Name _______ ide makes Hydro____ic Hypo____ite makes Hypo___ous ____ite makes _______ous ____ate makes ________ic Per___ate makes Per_____ic

For example, dealing with Cl. Chloride Hydrochloric Acid Cl- HCl Hypochlorite Hypochlorous Acid ClO- HClO Chlorite Chlorous Acid ClO2- HClO2 Chlorate Chloric Acid ClO3- HClO3 Perchlorate Perchloric Acid ClO4- HClO4

Nomenclature Review The Criss-Cross Method switches charges Remember to put the charge on the OUTSIDE of the parentheses for Polyatomic Ions – Magnesium Phosphate Mg3(PO4)2 Ionic Compounds combine the names of the ions Use the Roman Numeral for elements with more than one charge – Tin (II) Chloride, SnCl2 Covalent Compounds use the prefixes to tell how many of each element – Dinitrogen Pentoxide, N2O5