Formula Writing and Nomenclature

What is an ion?  An ion is a ______________.  It may be a ____ or ___charge.  Lose electrons  cation (+)  Gain electrons  anion (-) charged particle. +-

Why do atoms gain or lose electrons?  To become more ______.  Electrons come from ___________.  One ion ______ e- and the other _____e- to form a _____. stable other atoms gains loses bond

Do ions follow rules? YES!  Octet Rule: _____________  Tendency of valence electrons to rearrange to form a ________________.  THE MAGIC NUMBER=________  THE MAGIC NUMBER=________ The Rule of 8 stable/full valence shell Happy Happy Ion

Examples:  Na 2-8  F Opposites attract!  NaF

Do ions follow rules? YES!  Duet Rule:___________  For atoms so small their valence shell is the ______ energy level which can only hold ___________. The Rule of 2 first two electrons

Examples:  H can gain ___ e- to form _____.  H can lose ____ e- to form_____.  Li loses _____ e- to form _____.  Be loses ____ e- to form _____.  B loses _____ e- to form _____ H -1 H +1 Li +1 Be +2 B +3

Writing Formulas  All compounds have a charge of zero.  When writing formulas, all ions have to add up to zero.

IUPAC  IUPAC- International Union of Pure and Applied Chemists (created this naming system)

Forming Binary Ionic Compounds  Binary = two elements  Ionic = one metal and one nonmetal  Transfer of electrons  Not called molecules!

Writing Binary Ionics  Write each ion (metal first)  Crisscross the charges  Drop the + and –  Write numbers as subscripts

Binary Ionic Compounds  Example: magnesium chloride Mg +2 Cl -1 MgCl 2

Why does this work? Mg +2 Cl -1 MgCl 2 means…

Binary Ionic Compounds  Example: barium oxide Ba +2 O -2 BaO Ba 2 O 2

Practice  Sodium bromide  Calcium fluoride  Magnesium oxide  Lithium oxide  Aluminum oxide  Magnesium fluoride  Potassium iodide  Aluminum sulfide NaBr CaF 2 MgO Li 2 O Al 2 O 3 MgF 2 KI Al 2 S 3

Forming Ternary Ionics  Contain 3 or more elements  Combination of a metal and a polyatomic ion (Table E)

Writing Ternary Ionics  Write each ion (positive first)  Crisscross the charges  Drop the + and –  Write numbers as subscripts  Keep polyatomic ions in parentheses if more than 1  Never change a polyatomic ion!!!!!

Ternary Ionic Compounds  Example: ammonium chloride NH 4 +1 Cl -1 NH 4 Cl

Ternary Ionic Compounds  Example: lithium carbonate Li +1 CO 3 -2 Li 2 CO 3

Ternary Ionic Compounds  Example: calcium hydroxide Ca +2 OH -1 Ca(OH) 2

Why does this work? Ca +2 OH -1 Ca(OH) 2 means…

Practice  Magnesium hydroxide  Potassium sulfate  Sodium phosphate  Calcium nitrate Mg(OH) 2 K 2 SO 4 Na 3 PO 4 Ca(NO 3 ) 2

Stock System for Ionics  Some metals can have more than one oxidation state (i.e. transition metals)  Use roman numerals Examples: Copper (I) chloride Copper (II) chloride Cu +1 Cu +2 Cl -1 CuCl 2 CuCl Cl -1

Practice  Mercury (II) oxide  Vanadium (V) bromide  Copper (I) oxide  Tin (IV) bromide HgO VBr 5 Cu 2 O SnBr 4

Forming Molecular Compounds  Composed of two non-metals  Electrons are shared so no ions are formed (covalent bonding).  Called molecules  Prefix system- tells you how many atoms of each element

Prefixes prefixmeaning Mono-1 Di-2 Tri-3 Tetra-4 Penta-5 Hexa-6 Hepta-7 Octa-8 Nona-9 Deca-10

Molecular Compounds  Examples Carbon monoxide Carbon dioxide Phosphorous trichloride Phosphorous pentachloride Carbon tetrachloride CO CO 2 PCl 3 CCl 4 PCl 5

Practice  Phosphorous trichloride  Dichlorine monoxide  Sulfur tetrafluoride  Dinitrogen trioxide  Iodine monochloride PCl 3 Cl 2 O SF 4 N2O3N2O3 ICl

Naming Ionic Compounds Ionic Compounds (formula units)- Metal and non-metal Write cation name first (use roman numerals if more than one oxidation state). Write the first syllable of the anion and add –ide. OR just name the polyatomic ion

Examples: Ionics  LiBr  Na 2 SO 4  CuCl 2 lithium bromide sodium sulfate copper (II) chloride

Naming Molecular Cmpds Molecular Compounds (molecules)- two non-metals Use prefix system on first element (except Mono). Use prefix system on the second element (including mono) and add –ide ending

Examples: Molecular  N 2 O 5  CO  PCl 3 Dinitrogen pentoxide Carbon monoxide Phosporous trichloride

Empirical Formulas vs. Molecular Formulas  Compounds exist with a definite ratio of atoms (ex: water has 2 H per 1 O)  Empirical formula: lowest whole number ratio  Molecular formula: actual formula (can be empirical also).

Examples  C 2 H 8 is a molecular formula (can be reduced).  CH 4 is an empirical formula (can’t be reduced).