Nomenclature of Inorganic Compounds Chapter 6
Hein and Arena
Eugene Passer Chemistry Department Version 1.1 Bronx Community1 College © John Wiley and Sons, Inc Elements and Ions
2 The formula for most elements is the symbol of the element. Sodium Na Potassium K Zinc Zn Argon Ar Mercury Hg Lead Pb Calcium Ca
3 These 7 elements are found in nature as diatomic molecules.
Hydrogen H2
Nitrogen N2
Oxygen O2
Fluorine F2
Chlorine Cl2
Bromine Br2
Iodine I2
4 Formation of Ions
5 Positive Ion Formation: Loss of an Electron(s) From a Neutral Atom
Na Na+ + e-
Ca Ca2+ + 2e-
Al Al3+ + 3e-
6 Naming Cations
7 Cations are named the same as their parent atoms.
8 Atom sodium (Na)
Cation Na+
Name of sodium ion Cation 9 Atom calcium (Ca)
Cation Ca2+
Name of calcium ion Cation 10 Negative Ion Formation: Gain of an Electron(s) by a Neutral Atom
Cl + e- Cl-
O + 2e- O2-
N + 3e- N3-
11 Naming Anions
12 A monatomic anion consists of one element and has the stem of the parent element name with an –ide ending
13 Atom fluorine (F)
Anion F-
stem Name of fluoride ion Anion 14 Atom oxygen (O)
Anion O2-
stem Name of oxide ion Anion 15 Ions are always formed by adding or removing one or more electrons to or from a neutral atom.
16 Most often ions are formed when metals combine with nonmetals to form ionic solids with ionic bonds.
17 The charge on an ion can be predicted from its position in the periodic table.
18 elements of elementselements elementsof of of elements of Group Group IIA have Groupa Group VAGroup have VIA haveVIIAa havea a IA have a +1 charge +2 charge -3 charge-2 charge-1 charge
19 Writing Formulas From Names of Compounds
20 A chemical compound must have a net charge of zero.
21 If the compound contains ions, then the charges on all of the ions must add to zero.
22 Write the formula of calcium chloride.
Step 1. Write down the formulas of the ions. Ca2+ Cl- Step 2. Combine the smallest numbers of Ca2+ and Cl- so that the sum of the charges The cationThe is anion is writtenequalswritten first. zero.second. (Ca2+) + 2(Cl-) = 0 (2+) + 2(1-) = 0 The lowest common multiple The correct formula is CaCl2 of +2 and –1 23is 2 Write the formula of barium phosphide.
Step 1. Write down the formulas of the ions. Ba2+ P3- Step 2. Combine the smallest numbers of Ba2+ and P3- so that the sum of the charges The cationThe anionis is writtenwrittenequals first. second.zero. 3(Ba2+) + 2(P3-) = 0 3(2+) + 2(3-) = 0 The lowest common multiple The correct formula is Ba3P2 of +2 and –3 24is 6 Binary Compounds
25 Binary compounds contain two different elements only.
26 Naming Binary Compounds
27 Binary ionic compounds consist of a metal combined with a non-metal.
28 Binary Ionic Compounds Containing a Metal Forming Only One Type of Cation
29 • The chemical name is composed of the name of the metal followed by the name of the nonmetal which has been modified to an identifying stem plus the suffix –ide. • The number of atoms of each element present is not expressed in the name.
30 Name of Metal + Stem of Nonmetal with -ide ending
31 Examples
32 Compound NaCl
name of metal Name sodium chloride nonmetal stem
33 Compound MgCl2 name of metal Name magnesium chloride nonmetal stem
34 Binary Ionic Compounds Containing a Metal That Can Form Two or More Types of Cations
35 The Stock System
36 In IUPACthe Stock devisedSystem thethe Stockcharge Systemon theof cation is designatednomenclatureby toa nameRoman compoundsnumeral placed of in parenthesesmetals thatimmediately have more thanfollowing one typethe ofname of thecation.metal.
Cation +1 +2 +3 +4 +5 Charge Roman I II III IV V Numeral
The stem of the nonmetal name ends in -ide37 . Stock System LowerLower ChargeCharge HigherHigher Charge Charge Element Formula Name Formula Name
Copper Cu+ copper (I) Cu2+ copper (II)
Iron Fe2+ iron(II) Fe3+ iron(III)
Lead Pb2+ lead (II) Pb4+ lead(IV)
2+ 2+ Mercury Hg2 mercury(I) Hg mercury(II)
Tin Sn2+ Tin(II) Sn4+ Tin (IV) 38 Examples
39 iron(II) chloride
FeCl2
+2 -1 iron(II) chloride compoundionion charge name name iron(III) chloride
FeCl3
+3 -1
iron(III) chloride40 Binary Compounds Containing Two Nonmetals
41 Compounds between nonmetals are molecular, not ionic.
42 In a compound formed between two nonmetals, the element that appears first in the formula is named first.
43 Prefixes
44 Prefixes are used in a name to denote the number of atoms of each element present in a formula unit. Mono is rarely used when naming the first element, but mono is used in naming the second element (e.g. CO is carbon monoxide). • mono = 1 • hexa = 6 • di = 2 • hepta = 7 • tri = 3 • octa = 8 • tetra = 4 • nona = 9 • penta = 5 • deca = 10 45 Examples
46 dinitrogen trioxide
N2O3 indicates two indicates three nitrogen atoms oxygen atoms
47 dichlorine heptaoxide
Cl2O7
indicates two indicates seven chlorine atoms oxygen atoms
Why does chlorine appear first in the formula and oxygen second?
Oxygen is more electronegative than chlorine; the more electronegative element appears second in the formula and the name. Electronegativity is the relative ability of an atom in a bond to attract the bonding electrons toward itself and away from the atom it is bonded to. 48 Electronegativity increases from the lower left to the upper right for representative elements.
49 Step by Step Approach to Naming a Binary
Molecular Compounds, PCl5
Step 1 • Phosphorous and chlorine are nonmetals so the rules for naming a binary molecular compound applies. • Phosphorous is named first and chlorine second. (recall Cl is more electronegative: See 11.6). Therefore, in the name, phosphorous remains phosphorous and chlorine becomes chloride.
50 Step by Step Approach to Naming Binary Molecular Compounds, Cont.
Step 2 • No prefix is needed for phosphorous because there is only one phosphorous atom. The prefix penta- is used with chloride because there are 5 chlorine atoms present. Step 3 • The name is phosphorous pentachloride.
51 Examples
52 Cl2O3 dichlorine trioxide
53 N2O3 dinitrogen trioxide
54 Acids Derived from Binary Compounds of Hydrogen
55 Certain binary hydrogen compounds, when dissolved in water, form solutions that have acid properties. • The aqueous solutions of these compounds are given acid names.
56 Pure solid or gaseous compound HCl Hydrogen Chloride
Dissolved in water HCl Hydrochloric acid
57 • To write the formula of binary acids write the symbol of hydrogen first. • After hydrogen, write the symbol of the second element; typically a nonmetal.
• To name binary acids, place the prefix hydro- in front of the stem of the nonmetal name. • Then place the suffix -ic after the stem of the nonmetal name followed by acid. 58 Examples
59 Pure Solid or Gaseous Compound
HCl hydrogen chloride
60 Dissolved in Water
HCl hydrochloric acid
61 Pure Solis or Gaseous Compound
HI hydrogen iodide
62 Dissolved in Water
HI hydroiodic acid
63 Naming Compounds Containing Polyatomic Ions
64 A polyatomic ion is an ion that contains two or more elements. The nitrate anion is an example.
- NO3
65 66 • When naming a compound containing a polyatomic ion, name the cation first and then name the anion.
NaCO23
In writing the formula, the cation(s) appears
first followed by the polyatomic ion. 67 Oxy-acids
68 Oxy-acids contain hydrogen, a nonmetal, or a metal, and oxygen.
HClO3 or H2CrO4
69 Hydrogen in an The word acid in oxy-acid is not the name indicates expressed in the the presence of acid name. hydrogen.
70 Naming Oxy-Acids of Chlorine
HClO4 Perchloric Acid +1 oxygen
HClO3 Chloric Acid Root Acid
HClO2 Chlorous Acid - 1 oxygen HClO Hypochlorous Acid -2 oxygens HCl Hydrochloric Acid No oxygen*
* Please note HCl is not an oxy-acid Prefixes and Suffixes of Oxy-anions
72 Naming Oxy-Anions of Chlorine
- ClO4 Perchlorate +1 oxygen - ClO3 Chlorate Root Base - ClO2 Chlorite - 1 oxygen ClO- Hypochlorite -2 oxygens Cl- Chloride No oxygen*
* Please note Cl- is not an oxy-anion 74 75