Naming Compounds

Naming Compounds

What's in a name? That which we call a roseBy any other name would smell as sweet."

- William Shakespeare, Romeo and Juliet (II, ii)

Cl– Na+ Cl–

Ionic bondingIonic 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–1) 2)

3)

Na+

IonsSince ions are formed as a results of the

movement of electrons, ionic compounds will conduct electricity when

in solution

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

Rules for namingIonic 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 Mg2+ Br1-

need 2 Br1-

MgBr2

• 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. Fe2+ is iron(II) Fe3+ 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. OH1-, (SO4)2-,

Ba3(PO4)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, CuSO4, NH4NO3, Co2(CO3)3

- calcium hydroxide - copper(II) sulfate - ammonium nitrate - cobalt(III) carbonate

Ca(OH)2 CuSO4 NH4NO3 Co2(CO3)3

Compounds containing polyatomic ions

Practice namingIonic compounds

Give formulae & name: Ca + I, O + Mg, Na + S= Ca2I1 = CaI2 = calcium iodide= Mg2O2 = MgO = magnesium oxide= Na1S2 = Na2S = sodium sulfide

Naming covalent compounds• -ide ending, each element has “prefix”1 mono

2 di3 tri4 tetra5 penta6 hexa7 hepta8 octa9 nona10 deca

• prefix refers to # of atoms - not valenceN2O4 = dinitrogen tetroxide

• Exception: drop mono for first elementCO2 = carbon dioxide

• The first vowel is often dropped to avoid the combination of “ao” or “oo”.

CO = carbon monoxide (monooxide)

SO2= sulfur dioxide (doxide)• Name: CCl4, P2O3, IF7

P4O10= tetraphosphorus decoxide

Write and name the following covalent compounds

carbon tetrachloride

diphosporus trioxide

iodine heptafluoride

CCl4

P2O3

IF7