Naming in chemistry

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CHEMICAL BASIS OF ENGINEERING

Inorganic NomenclatureInorganic NomenclatureInorganic NomenclatureInorganic Nomenclature

IUPAC = International Union of Pure and Applied Chemists. It determines the official

nomenclature for all chemical elements and compounds.

A chemical formula is a way to represent the composition of a certain compound. It is

based on the elements symbols and the number of atoms of each element found in

each molecule or compound.

Each constituent element is represented by its chemical symbol and a subscript on the

right hand side indicates the number of atoms of each element found in each discrete

molecule of that compound.

It is written as follows:

1. The chemical symbol of the element(s)

2. The number of atoms of each element present written as numerical

subscript on the right hand side of the symbol.

Examples:

- H2O: 2 H + 1 O atoms - Al2O3: 2 Al + 3 O atoms

- HF: 1 H + 1 F atoms - HClO4: 1 H + 1 Cl + 4 O atoms

- C2H6O: 2 C + 6 H + 1 O atoms - CaO: 1 Ca + 1 O atoms

INORGANIC NOMENCLATUREBasic concepts

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A molecular formula shows the exact number of atoms of each element in the

smallest unit of a substance.

A structural formula provide a representation of the molecular structure of the

molecule in the space, indicating the arrangement of the atoms.


Estructural formulaMolecular formula

C4H10O CH3 - CH – CH2 - OH

CH3

An empirical formula shows the simplest non-reducible number ratio of theatoms in a substance. It corresponds to the lowest whole number ratio of theatoms.

Molecular formula

C6H6

N2H4

C2H8O2

Empirical formula Molecular formula

CH2Cl2

H2O2

CaC2O4

Empirical formula

Oxidation state:

Describes the combining power of an atom in a certain compound (also known as valence).

The formal oxidation state it is sometimes defined as the hypothetical charge that an atom

would have if all bonds to atoms of different elements were 100% ionic.

Valence :

Denotes the number of electrons in the outermost energy level.

Group 1 (Alkaline Metals): Li, Na, K, Rb, Cs, Fr (+1)Group 2 (Alkaline Earth Metals): Be, Mg, Ca, Sr, Ba, Ra (+2)Group 13: B, Al, Ga, In, Tl (+3)Group 14: C, Si, Ge, Sn, Pb (+4, -4)Group 15: N, P, As, Sb, Bi (+3, +5)Group 16: O (-2), S, Se, Te, Po (+2, +4, +6)Group 17 (Halogens): F (-1), Cl, Br, I, At (-1, +1, +3, +5, +7)


Most common oxidation states of the chemical elements:

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Ionic compounds are typically composed of a metal and a non-metal. An ionic

compound is named by its cation (metal) followed by its anion (non-metal).

INORGANIC NOMENCLATURENaming Ionic Compounds

a) Anions

Monoatomic anions are named with an -ide suffix.

Ex.: H− is hydride or Cl- is chloride.

b) Cations

Most cations are derived from metal atoms. Metal cations take their names from the

elements they come from followed by the word ‘ion’ or ‘cation’.

(exception: NH4+: ammonium ion)

Ex.: Na+ is sodium ion or sodium cation

For cations that take on multiple oxidation states, the oxidation state is written using

Roman numerals in parentheses immediately following the element name.

Ex.: Fe3+ is Ferric Ion (III) or Iron cation (III)

The charge of the ion is indicated as a superscript that can be either positive (cations) or

negative (anions).


Monoatomic Anions

H– Hydride

F– Fluoride

Cl– Chloride

Br– Bromide

I– Iodide

O2– Oxide

S2– Sulfide

Se2– Sellenide

Te2– Telluride

N3– Nitride

P3– Phosphide

Polyatomic Anions

NO2– Nitrite

NO3– Nitrate

N3- Nitride

SO32– Sulfite

SO42– Sulfate

S2O32- Thiosulfate

HSO4– Hydrogen sulfate

HSO3– Hydrogen sulfite (bisulfite)

OH– Hydroxide

CN– Cyanide

PO43– Phosphate

HPO42– Hydrogen phosphate

H2PO4– Dihydrogen phosphate

CO32– Carbonate

HCO3– Hydrogen carbonate or

bicarbonate

ClO– Hypochlorite

ClO2– Chlorite

ClO3– Chlorate

ClO4– Perchlorate

C2H3O2– Acetate

O22– Peroxide

MnO4– Permanganate

CrO42– Chromate

Cr2O72– Dichromate

SCN- Thiocyanate

BO33− Borate

AsO43− Arsenate

C2O42− Oxalate

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Monoatomic Cations

H+ Hydrogen

Li+ Lithium

Na+ Sodium

K+

Rb+

Potassium

Rubidium

Cs+ Caesium

Ag+ Silver

Mg2+ Magnesium

Ca2+ Calcium

Sr2+ Strontium

Ba2+ Barium

Zn2+ Zinc

Cd2+ Cadmium

Al3+ Aluminum

Cr2+ Chromium (II) Chromous

Cr3+ Chromium (III) Chromic

Co2+ Cobalt (II) Cobaltous

Co3+ Cobalt (III) Cobaltic

Cu+ Copper (I) Cuprous

Cu2+ Copper (II) Cupric

Fe2+ Iron (II) Ferrous

Fe3+ Iron (III) Ferric

Pb2+ Lead (II) Plumbous

Pb4+ Lead (IV) Plumbic

Mn2+ Manganese (II) Manganous

Mn3+ Manganese (III) Manganic

Hg2 2+ Mercury (I) Mercurous

Hg2+ Mercury (II) Mercuric

Sn2+ Tin (II) Stannous

Sn4+ Tin (IV) Stannic

Hg22+ Mercury(I) / mercurous ; NH4

+ Ammonium

H3O+ Hydronium;

Polyatomic Cations

Binary ionic compounds

METAL – NON-METAL

Examples:

NaCl: Sodium chloride

KCl: Potassium chloride

KBr: Potassium bromide

CsCl: Caesium chloride

Name of the metal (cation) + root of the Non-metal (anion) + ‘- ide’

For ionic compounds to be electrically neutral, the sum of the charges on the cation and

anion in each formula unit must be zero. The subscript of the cation is numerically equal to

the charge on the anion and viceversa, the subscript of the anion is numerically equal to the

charge on the cation (the criss-cross rule).

Ex.:

Calcium Fluoride

CaCa2+2+ FF--

CaCa FF 22


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Binary ionic compounds

METAL – NON-METAL

Examples:

CaF2: Calcium fluoride

LiO2: Lithium oxide

BaO: Barium oxide

FeCl2: Ferrous chloride or Iron (II) chloride

FeCl3: Ferric chloride or Iron (III) chloride

SnCl4: Stannic Chloride or Tin (IV) chloride or Tin tetrachloride

SnCl2: Stannous Chloride or Tin (II) chloride or Tin dichloride

Name of the metal (cation) + root of the Non-metal (anion) + ‘- ide’

When the oxidation numbers of both elements are numerically equal but greater than 1, the subscripts are not also written (Ex. CaO; CaCO3).


Ternary ionic compounds

METAL – NON-METAL

Examples:

LiOH: Lithium hydroxide

Ca(OH)2: Calcium hydroxide

NaCN: Sodium cyanide

CaCO3: Calcium carbonate

K2SO4: Potassium sulfate

NaHCO3: Sodium bicarbonate

AlPO4: Aluminum phosphate

Na2SO3: Sodium sulfite

KClO4: Potassium perchlorate

Name of the metal (cation) + root of the anion + ‘- ide’ or + ‘-ate’ or + ‘-ite’


Name the cation + name the (polyatomic) anion

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Hydrogen derivatives

METAL – NON-METAL (H)

Examples:

LiH: Lithium hydride

KH: Potassium hydride

BeH2: Berilium hydride

AlH3: Aluminum hydride

Name of the metal (cation) + hydride

INORGANIC NOMENCLATURENaming Inorganic Compounds

H – NON-METAL

Hydrogen + root of non-metal + -ide

In aqueous solution

Other combinations of H

NH3: ammonia (Nitrogen trihydride)

PH3: phosphine (Phosphorous trihydride)

AsH3: Arsane (Arsenic trihydride)

SbH3: Stibine (Antimony trihydride)

CH4: Methane

SiH4: Silane (Silicon hydride or tetrahydride)

Examples:

HF: Hydrogen fluoride Hydrofluoric acid or Fluorhydric acid

HCl: Hydrogen chloride Hydrochloric acid or Chlorhydric acid

H2S: Hydrogen sulfide Hydrosulfuric acid or Sulfhydric acid

Oxygen derivatives

METAL – NON-METAL (O)

Examples:

LiO2: Lithium oxide

KO2: Potassium oxide

CaO: Calcium oxide

Fe2O3: Iron (III) oxide (or ferric oxide)

Name of the metal (cation) + oxide

INORGANIC NOMENCLATURENaming Inorganic Compounds

H – NON-METAL

Examples:

HF: Hydrogen fluoride Hydrofluoric acid or Fluorhydric acid

HCl: Hydrogen chloride Hydrochloric acid or Chlorhydric acid

H2S: Hydrogen sulfide Hydrosulfuric acid or Sulfhydric acid

Hydrogen + root of non-metal + -ide

In aqueous solution

METAL – NON-METAL (X)

X = F, Cl, Br, I

Name of the metal (cation) + root of X + - ide

NaCl: Sodium chloride

LiBr: Lithium bromide

Halogen derivatives

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If there is more than one of a given element,

we use prefixes to indicate the number of each

kind of atom present.

Naming Molecular Compounds

The prefix mono is only used for atoms that can formmore than one compound with the second element.For this class, oxygen is the main element that doesthis.


NF3 nitrogen trifluoride

SO2 sulfur dioxide

N2Cl4 dinitrogen tetrachloride

NO2 nitrogen dioxide

N2O dinitrogen monoxide (laughing gas)

To name chemical compounds you should know…

1. The symbols of elements and radicals

2. Corresponding valence or oxidation numbers

3. Irregular names for chemical elements or their derivatives

(i.e. argentums)


Stannic Chloride - Sn+4Cl-1 → SnCl4

Stannous Chloride - Sn+2Cl-1 → SnCl2

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Naming in chemistry