CHEMICAL SYMBOLS AND FORMULAE

SYMBOL SOFELEMENT

An element is a substance which consists of only one kind of matter Over 100 elements are known, these elements are usually represented by symbols instead of writing their names in full. The abbreviation for each element is called Symbol for that element.

The brief name of that element it represents also one atom of the element it stands for. (Element1–20)

There are 4 groups of symbols:

Symbols formed from the first letter of element

Element Symbols

Hydrogen H

Carbon C

Nitrogen N

Oxygen O

Sulphur S

Phosphorus P

Iodine I

Fluorine F

(b) Symbols formed from the first two letter of the element.

Elements Symbols

Helium He

Lithium Li

Beryllium Be

Neon Ne

Aluminum Al

Calcium Ca

Barium Ba

Bromine Br

Elements Symbols

Magnesium Mg

Chlorine Cl

Manganese Mn

Zinc Zn

Cadmium Cd

Platinum Pt

(d) Symbols derived from latin name of the elements

Element Latin Name Symbols

Sodium Natrium Na

Iron Ferrum Fe

Copper Cuprum Cu

Gold Aurum Au

Potassium Kalium K

Silver Argentun Ag

Lead Plumbum Pb

Mercury Hydragyrum Hg

ELECTRONICCON FIGURATION

Electronic Configuration is the representation of how electrons are arranged on the shells of an element.

The pattern of how electrons are arranged is of the fashion:

K 1^stshell–2electrons

L 2^ndshell–maximumof8electrons

M 3^rdshell–maximumof8electrons

N 4^thshell–maximumof8electrons

This pattern works for at least the first 20elements.

The electronic configuration helps us to correctly place elements into their groups and period within periodic table. This information also helps in the determination of combining powers of elements.

GROUP AND VALENCY

The group refers to the vertical arrangement in columns of elements in the periodic table. Valency is the combining power of an element. It must be correctly determined and the correct chemical formulae of compound were to be determined.

Group Valency

I +1

II +2

III +3

IV –4

V –3

VI –2

VII -1

O 0

FORMULAE OF BINARY COMPOUND

Formulae of binary compound

A compound is a substance made of 2 or more elements chemically combined together. Compound of 2 elements only are known as binary compounds and have the following characteristics.

Name send with–IDE.

E.g. Carbon dioxide, Magnesium chloride, Aluminum Oxide, Aluminum Chloride.

C=6______2,4 Al=13______2,8,3

Mg=12______2, 8, 2O=8______2, 6

Cl=17 _______2, 8, 7

Mg Cl A1 0

+2 1 +3 2

MgC1₂ Al₂0₃

Al C

+3 -4

Al₄C₃

NON-BINARYCOMPOUNDS

These are compounds of 2 or more elements whose name send with ATE examples are: Magnesium trioxocarbonate (IV)

Beryllium trioxonitrate (V)

Calcium tetraoxosulphate (VI)

Potassium heptaxodichromate VI

Sodium hexachloroplatimate II

Non-binary compounds have these characteristics:

DETERMINATIONOFVELENCIESOFRADICALS

Radicalsaregroupofatomsbearinga charge.Theyarethepolyatomicionsi.e.ionswhichcontainmorethanonetypeofatom.Exampleinclude;

Trioxonitrate (V) ion N0₃^–
Trioxocarbonate(IV) ion C0₃^2-
Tetraoxosulphate(VI) ion S0₄^2–
Hydroxideion OH^–
Cyanideion CH^–
Tetraoxophosphate (V) ion PO₄^3-
Hydrogentrioxocarbonate(IV)ion HC0₃^–

The charge one achpoly atomic ionis determined thus:

S+4(O)

But O=-2andS=6

S+4(-2)

6–8=-2

SO4^2-

CO₃^2-

C+3(O)

But C=4,O=-2

4+3(-2)

4–6=-2

C0₃^2-

FORMULAE OF NON-BINARY COMPUNDS

Sodium hexachloroplatinate II

Na=11________2, 8, 1

Valency of sodium =1

Hexachlroroplatinate II = PtCl₆

Pt+6Cl

2+6(-1)

2–6

=-4

ValencyofPtCl₆=-4

Na PtCl₆

1 4

Na₄PtCl₆

IUPAC NOMECLATURE

International Union of Pure and Applied Chemistry have agreed to a common way of naming chemical compounds according to a set of rules, these naming system is termed IUPAC nomenclature.

The rules involved in IUPAC nomenclature are as follow:

Take oxygen as–2.

Hydrogen as +1 with non-metals.

Hydrogen as–1 with metals.

These numbers are the oxidation number.

C0₃^2-

C+3(-2)=-2

C–6=-2

C=-2+6=+4

Name = trioxocarbonate (IV) ioni.e.3atoms of oxygen and carbon oxidation number is 4.