Naming Compounds What's in a name? That which we call a rose By any other name would smell as sweet." - William Shakespeare, Romeo and Juliet (II, ii)

Cl – Na + Cl – Ionic bonding Ionic bonding involves 3 steps 1) loss of an electron(s) by one element, 2) gain of electron(s) by a second element, 3) attraction between positive and negative Na Cl e–e– 1) 2) 3) Na +

Ions Since ions are formed as a results of the movement of electrons, ionic compounds will conduct electricity when in solution

Covalent bonding If two atoms have approximately the same pull on electrons, they share the electrons (forming a “covalent” bond)

Rules for naming Ionic compounds MONATOMIC IONS (single atom ions) Metal ions form positive ions : CATIONS Metal (+ ion) comes 1st Names Identified simply by the elements name Negative ions : ANIONS Drop the ending and replace with -ide. Example: sodium chloride Do not capitalized unless starting a sentence

Binary Compounds (compounds composed of two elements) Total number of positive charges and negative charges must be equal Use valence electrons to balance name of cation name of anion Example: magnesium bromide Mg 2+ Br 1- need 2 Br 1- MgBr 2

Some metals form 2 or more cations with different charges As before, positive metal comes first The charge (valence) of the metal is indicated in brackets using roman numerals the anion ends in –ide e.g. Fe 2+ is iron(II) Fe 3+ is iron(III)

Element (charge) Name Cu (1,2)copper (I), copper(II) Fe (2,3)iron(II), iron (III) Pb (2,4)lead(II), lead(IV) Sn (2,4)tin (II), tin (IV) Co (2,3)cobalt (II), cobalt (III) Cr (2,3)chromium(II) chromium(III) Mn (2,3)manganese(II), manganese(III) Hg (1,2)mercury (I), mercury (II)

Groups of atoms can also have valences “Polyatomic ions” are groups of atoms that interact as a single unit e. g. OH 1-, (SO 4 ) 2-, Ba 3 (PO 4 ) 2 = Polyatomic Ions barium phosphate Naming compounds with polyatomic ions is similar to naming other ionic compounds You should note that compounds with polyatomic ions have names ending in -ate or -ite not -ide Note that most are negative, except ammonium Name: Ca(OH) 2, CuSO 4, NH 4 NO 3, Co 2 (CO 3 ) 3

- calcium hydroxide - copper(II) sulfate - ammonium nitrate - cobalt(III) carbonate Ca(OH) 2 CuSO 4 NH 4 NO 3 Co 2 (CO 3 ) 3 Compounds containing polyatomic ions

Practice naming Ionic compounds Give formulae & name: Ca + I, O + Mg, Na + S = Ca 2 I 1 = CaI 2 = calcium iodide = Mg 2 O 2 = MgO = magnesium oxide = Na 1 S 2 = Na 2 S = sodium sulfide

Naming covalent compounds -ide ending, each element has “prefix” 1mono 2di 3tri 4tetra 5penta 6hexa 7hepta 8octa 9nona 10deca prefix refers to # of atoms - not valence N 2 O 4 = dinitrogen tetroxide Exception: drop mono for first element CO 2 = carbon dioxide The first vowel is often dropped to avoid the combination of “ao” or “oo”. CO = carbon monoxide (monooxide) SO 2 = sulfur dioxide (doxide) Name: CCl 4, P 2 O 3, IF 7 P 4 O 10 = tetraphosphorus decoxide

Write and name the following covalent compounds carbon tetrachloride diphosporus trioxide iodine heptafluoride CCl 4 P 2 O 3 IF 7