psc 4012 ionic phenomena: a study of an environmental problem

PSC 4012

Ionic Phenomena:

A study of an environmental problem

PSC 4012: Nomenclature

Element: molecule of only one element. Example: Au (Gold), Ag (Silver)

Diatomic molecules: molecule of one element, two atoms. Example: Cl2 (Chlorine), N2 (Nitrogen)

Binary compounds: molecule of two elements, two or more atoms. Example: NaCl (Sodium Chloride), Al2O3 (Aluminum Oxide)

Complex compounds: molecules of more than two elements. Example: H2SO4 (Sulfuric Acid)


Element: molecule of only one element. Example: Au (Gold), Ag (Silver)

Diatomic molecules: molecule of one element, two atoms. Example: Cl2 (Chlorine), N2 (Nitrogen)

Rules for naming: Simply state the name of the element (according to Periodic

Table) No need to use prefixes (unless indicated, if writing

chemical formula for diatomic molecules)


Binary compounds: molecule of two elements, two or more atoms. Example: NaCl (Sodium Chloride), Al2O3 (Aluminum Oxide)

Two types of binary compounds: Binary molecular compounds (between two non-

metals) Binary ionic compounds (between a metal and a non-

metal)


Binary molecular compounds: molecule of two non-metal elements.

Rules for naming: Name first element in formula first (name remains

unchanged) Name second element in formula second. Change its

last syllable (or last two syllables) to (-ide) Use prefixes according to the subscripts present for

each element


Element Name in formula

Chlorine chloride

Oxygen oxide

Hydrogen hydride

Carbon carbide

Nitrogen nitride

Sulphur sulphide

Subscript Prefix

1 Mono-*

2 Di-

3 Tri-

4 Tetra-

5 Penta-

6 Hexa-

7 Hepta-

8 Octa-

9 Nona-

10 Deca-

Page 4.6



Example: HI First element is hydrogen (H), stays the same Second element is iodine (I), changes to iodide Compound’s name: hydrogen iodide



Example: N2O4

First element is hydrogen (N), stays the same. Needs to add prefix, 2 atoms, so “dinitrogen”

Second element is oxygen (O), changes to oxide. Needs to add prefix, 4 atoms, so “tetraoxide”

Compound’s name: dinitrogen tetraoxide



Practice: P2S5

First element is phosphorous (P), stays the same. Needs to add prefix, 2 atoms, so “diphospohorous”

Second element is sulphur (S), changes to sulphide. Needs to add prefix, 5 atoms, so “pentasulphide”

Compound’s name: diphosphorous pentasulphide



Example: Write the chemical formula of Sulphur trioxide First element mentioned appears first in formula:

sulphur, so S Second element mentioned, appears second in formula:

oxide, which refers to oxygen, so O According to prefixes, there are 1 S and 3 O Compound’s formula: SO3



Practice: Write the chemical formula of dinitrogen pentaoxide

First element mentioned appears first in formula: nitrogen, so NSecond element mentioned, appears second in formula: oxide, which refers to oxygen, so OAccording to prefixes, there are 2 N and 5 OCompound’s formula: N2O5


Binary ionic compounds: molecule of a metal and a non-metal.

Rules for naming: Name the cation, first element in formula, first (name

remains unchanged) When cation has more than one possible charge, a roman

numeral in bracket, should follow cation’s name (mainly for transition metals, e.g. Cu, Fe, etc.) Table 4.1, p. 4.13

Name the anion changing its last syllable (or last two syllables) to (-ide)

No prefixes are used



Example: KBr

First element in formula is cation potassium (K+) Second element in formula is anion bromide (Br -) Compound’s name: potassium bromide



Example: CaCl2

First element in formula is cation calcium (Ca2+) Second element in formula is anion chloride (Cl -) Compound’s name: calcium chloride



Example: CuCl2

First element in formula is cation copper (Cu2+) Second element in formula is anion chloride (Cl -) Compound’s name: copper (II) chloride



Practice: CaO

First element in formula is cation calcium (Ca2+)

Second element in formula is anion oxide (O2-) Compound’s name: calcium oxide



Practice: Fe3N2

First element in formula is cation iron (Fe2+)

Second element in formula is anion nitride (N3-) Compound’s name: iron(II) nitride



Example: Write the chemical formula of Magnesium sulphide First, cation mentioned, which appears first in formula:

magnesium, so Mg2+

No roman numeral Second, anion mentioned, which appears second: sulphide, so

S2-

Both ions are Mg2+ and S2-

Crossover rule: Mg2S2

Chemical formula: MgS



Example: Write the chemical formula of iron (III) oxide First, cation mentioned, which appears first in formula: iron,

so Fe2+ or Fe3+ (Table 4.1, p. 4.13) Roman numeral: III, so charge is 3+, therefore Fe3+

Second, anion mentioned, which appears second: oxide, so O2-

Both ions are Fe3+ and O2-

Crossover rule: Fe2O3

Chemical formula: Fe2O3



Practice: Write the chemical formula of lithium carbide

First, cation mentioned, which appears first in formula: lithium, so Li+

No roman numeralSecond, anion mentioned, which appears second: carbide, so C4-

Both ions are Li+ and C4-

Crossover rule: Li4C

Chemical formula: Li4C



Practice: Write the chemical formula of copper (II) fluoride

First, cation mentioned, which appears first in formula: copper, so Cu1+ or Cu2+ (Table 4.1, p. 4.13)Roman numeral: II, so charge is 2+, therefore Cu2+

Second, anion mentioned, which appears second: fluoride, so F-

Both ions are Cu2+ and F-

Crossover rule: CuF2

Chemical formula: CuF2


Complex compounds: molecules of more than two elements. (Polyatomic ions)

Rules for naming: Name the cation, first element in formula, first (name

remains unchanged) When cation has more than one possible charge, a roman

numeral in bracket, should follow cation’s name (mainly for transition metals, e.g. Cu, Fe, etc.) Table 4.1, p. 4.13

Name the polyatomic anion Table 4.1, p. 4.13 No prefixes are used



Example: CaSO4

First element in formula is cation calcium (Ca2+) Second element in formula is polyanion sulphate

(SO42-) Table 4.1, p. 4.13

Compound’s name: calcium sulphate



Example: CuCrO4

First element in formula is cation copper (Cu1+or Cu2+) Table 4.1, p. 4.13

Second element in formula is polyanion chromate (CrO42-)

Table 4.1, p. 4.13 According to formula, and crossover rule, cation must be Cu2+

(Cu2+ CrO42- = CuCrO4 instead of Cu2CrO4 for Cu1+)

Compound’s name: copper (II) chromate



Practice: BaCO3

First element in formula is cation calcium (Ba2+)

Second element in formula is polyanion carbonate (CO3

2-) Table 4.1, p. 4.13

Compound’s name: barium carbonate



Practice: Fe3(PO4) 2 First element in formula is cation iron (Fe2+or Fe3+) Table 4.1, p. 4.13Second element in formula is polyanion phosphate (PO4

3-) Table 4.1, p. 4.13According to formula, and crossover rule, cation must be Fe2+

(Fe2+ PO43- = Fe3(PO4) 2 instead of FePO4 for Fe3+)

Compound’s name: iron (II) phosphate



Example: Write the chemical formula of Magnesium sulphate First, cation mentioned, which appears first in formula: magnesium, so

Mg2+

No roman numeral Second, polyanion mentioned, which appears second: sulphate, so SO4

2-

(Table 4.1, p. 4.13) Both ions are Mg2+ and SO4

2-

Crossover rule: Mg2(SO42-)2

Chemical formula: MgSO4



Example: Write the chemical formula of iron (III) carbonate First, cation mentioned, which appears first in formula: iron, so Fe2+

or Fe3+ (Table 4.1, p. 4.13) Roman numeral: III, so charge is 3+, therefore Fe3+

Second, polyanion mentioned, which appears second: carbonate, so CO3

2-(Table 4.1, p. 4.13)

Both ions are Fe3+ and CO32-

Crossover rule: Fe2(CO3)3

Chemical formula: Fe2(CO3)3



Practice: Write the chemical formula of Sodium nitrate

First, cation mentioned, which appears first in formula: sodium, so Na+

No roman numeralSecond, polyanion mentioned, which appears second: nitrate, so NO3

-

(Table 4.1, p. 4.13)Both ions are Na+ and NO3

-

Crossover rule: Na NO3

Chemical formula: Na NO3



Example: Write the chemical formula of copper (II) borateFirst, cation mentioned, which appears first in formula: copper, so Cu+ or Cu2+ (Table 4.1, p. 4.13)Roman numeral: II, so charge is 2+, therefore Cu2+

Second, polyanion mentioned, which appears second: borate, so BO33-

(Table 4.1, p. 4.13)Both ions are Cu2+ and BO3

3-

Crossover rule: Cu3(BO3)2

Chemical formula: Cu3(BO3)2

psc 4012 ionic phenomena: a study of an environmental problem

Documents

element slide

nomenclature binary

o compounds formula

nitrogen binary compounds

s second element

types of binary compounds

iodide compounds

pentasulphide compounds