CHEMICAL SYMBOLS AND FORMULAE

CHEMICAL SYMBOLS AND FORMULAE

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CHEMICAL SYMBOLS AND FORMULAE  

SYMBOLSOFELEMENT

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

 

(c)    Symbols formed from the first and any letter in the name of the elements

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          1stshell–2electrons

L          2ndshell–maximumof8electrons

M        3rdshell–maximumof8electrons

N         4thshell–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;

  1. Trioxonitrate (V) ion             N03
  2. Trioxocarbonate(IV) ion             C032-
  3. Tetraoxosulphate(VI) ion             S042–
  4. Hydroxideion             OH
  5. Cyanideion             CH
  6. Tetraoxophosphate (V) ion             PO43-
  7. 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

SO42-

 

CO32-

C+3(O)

But      C=4,O=-2

4+3(-2)

4–6=-2

C032-

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.

C032-

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.

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