Chemical Formula 1

8/8/2019 Chemical Formula 1

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Chemical

Formulae


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Learning Objectives

Student should be able to:1.State the meaning of chemical

formula

2.Write ionic formulae of ions.

3.Construct the chemical formula ofionic compounds


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INTRODUCTION

IONIC COMPOUND


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Chemistry is a very

systematic field of study.

Every chemical substance is

given a name and a chemicalformula.

INTRODUCTION


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Chemistry is a very

systematic field of study.

Every chemical substance is

given a name and a chemicalformula.

A chemical formula is

representation of a chemical

substance using letter for

atoms and subscript numbers

to show the number of each

type of atoms that are presentin the substance.

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Based on the chemical

formula of a substance, weknow the composition of the

substance.

Chemical formulae is dividedinto two types. There are:

i. Element ii.

compound


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1Element ???

Compound??

Examples ofelement

Examples of

compound


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A substance composed of

atoms having an identical

number of protons in each

nucleus. Elements cannot

be reduced to simplersubstances by normal

chemical means.

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Element


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macroscopicallyhomogeneous substance

consisting of atoms or ions

of two or more different

elements in definite

proportions that cannot beseparated by physical

means. A compound usually

has properties unlike those

of its constituent elements.

compound


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1Carbon

Argon

Oxygen gas

Copper

Chlorine gas

Carbon is made up of carbon

atoms

Chemical formula:

C

Argon is made up of argon

atoms

Chemical formula:

Ar

Copper is made up of copper atoms

Chemical formula:

Cu

Cu

Each oxygen molecule consists of

two oxygen atoms.

Chemical formula:

O2

Each chlorine molecule consists of

two chlorine atoms

Chemical formula:Cl2

Element


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1WATER

AMMONIA

SULPHURIC ACID

ZINC HYDROXIDE

MAGNESIUM

NITRATE

Chemical formula:

H2O

Element present:

Hydrogen, oxygen

Ratio:

H = 2, O = 1

Chemical formula:

NH3

Element present:

Nitrogen, hydrogen

Ratio:

N=1, H=3

Chemical formula:

H2SO4

Element present:

Hydrogen, sulphur, oxygen

Ratio:

H=2, S=1, O=4

Chemical formula:

Zn(OH)2

Element present:

Zinc, oxygen, hydrogen

Ratio:

Zn=1, O=2, H=2

Chemical formula:

Mg(NO)3

Element present:

Magnesium, nitrogen, oxygen

Ratio:

Mg=1, N=3, O=3

compound


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IONIC COMPOUND

Ionic compounds consist of cation

and anionsi. Cations are positive charged ions.

ii. Anions are negatively-chared ions.


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In chemistry, an ionic

compound is a

chemical compound in

which ions are held

together in a lattice

structure by ionicbonds. The positively

charged ion is usually a

metal ion and the

negatively charged ion

is non-metallic elementor molecule.

Ionic compound


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Example of ionic compounds:

Sodium chloride Caesium chloride


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2Chloride, Cl- Sodium, Na

+

Sodium chloride

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caesium

Chloride

Caesium chloride

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To construct chemicalformulae of ionic compounds,

we need to know the formula

of cations and anions.


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2Charge of ion Cation Formula of cation

+1

Sodium ion Na+

Potassium ion K+

Silver ion Ag+

Hydrogen ion H+

Ammonium ion NH4+

Copper(I) ion Cu+

+2

Calcium ion Ca2+

Magnesium ion Mg2+

Zinc ion Zn2+

Student can check spelling with click on the

element..


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2Charge of ion Cation Formula of cation

+2

Barium ion Ba2+

Iron(II) ion Fe2+

Copper(II) ion Cu2+

Tin(II) ion Sn2+

Lead(II) ion Pb2+

+3

Iron(III) ion Fe3+

Aluminium ion Al3+

Chromium(III) ion Cr3+

+4 Lead(IV) ion Pb4+

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element..


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2Charge of anion anion Formula of anion

-1

Flouride ion F-

Chloride ion Cl-

Bromide ion Br-

Iodide ion I-

Hydroxide ion OH-

Nitrate ion NO3-

Nitrite ion NO2-

Hydride ion H-

Manganate (VII) ion MnO4-


element..


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2Charge of anion anion Formula of anion

-2

oxide ion O2-

carbonate ion CO32-

sulphide ion S2-

sulphate ion SO42-

sulphite ion SO32-

thiosulphate ion S2032-

Chromate(VI) ion CrO42-

Dichromate(VI) ion Cr2O7

2-

-3 Phosphate ion PO43-

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element..

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Chemical Formula 1