Chapter 6 Chemical Names and Formulas Intro to Chemical Bonding

Molecular Compounds Naming compounds is an essential skill in Chemistry. Molecule= smallest electrically neutral unit of a substance that still has properties of that substance. Molecular compounds- compounds composed of molecules.

Anions and Cations Metals are losers!! Lose Electrons  therefore have a positive charge (cations) Mg ( tends to lose 2e)  Mg 2+ Non-metal elements form ions by gaining electrons ( anions) Name of anion usually ends in --ide. Cl ( tends to gain e) -  Cl- chloride

Ionic Compounds Compounds with cations and anions = Ionic Compounds Metal with Non-metal Physical state = solid M.P. = high Chemical formula- # of atoms in the smallest representative unit of a substance.

Ionic Compounds Ionic Compounds have Formula Units = The lowest whole # ratio of ions in a compound. NaClMgCl 2 1:1 1:2

Diatomic Molecules *** BrINClHOF**** ( Brinkle Hof) Bromine Iodine Nitrogen “ Scaredy Cat Elements” Chlorine Hydrogen Oxygen Flourine *** BrINClHOF**** ( Brinkle Hof) Bromine Iodine Nitrogen “ Scaredy Cat Elements” Chlorine Hydrogen Oxygen Flourine

Compound Laws Law of definite proportions: In samples of any chemical cpd, the masses of the elements are always in the same proportions. eg: MgS Law of multiple proportions: Whenever 2 elements form more than one cpd, the different masses of one element that combine with the mass of the other element are in small whole numbers. eg: H 2 O H 2 O 2

Monatomic Ions Group 1A2A3A4A5A6A7A0 Li⁺ Be²⁺ N³¯ O²¯ F¯ Na⁺ Mg²⁺ Al³⁺ P³¯ S²¯ Cl¯ K⁺ Ca²⁺ Se²¯ Br¯ Rb⁺ Sr²⁺ I¯ Transition Metals- have more than one common ionic charge. -- ous cation with lower ionic charge -- ic cation with higher of two ionic charge Exceptions : Ag⁺ Cd²⁺ Zn²⁺ Al³⁺

Polyatomic Ions Polyatomic ions = tightly bound groups of atoms that behave as a unit and carry a charge. Eg: NH 4 ⁺ SO₄²¯ PO₄³¯ NO₃¯ ammonium sulfate phosphate nitrate ion anion anion ion Most polyatomic anions end in -ite or -ate Except: NH₄⁺ ammonium ion CN¯ cyanide ion OH¯ hydroxide ion

Writing Formulas Cation first, then anion Rust = iron (III) oxide Fe³⁺ O²¯ 3⁺x 2=6⁺ 2¯x3= 6¯ balanced, therefore the compound is Fe₂O₃ Crisscross Method