Compound
Compound

source : online-sciences.com

Compound-

Substance made up of two or more elements chemically combined in a fixed proportion by weight.

Ex . Water always contains hydrogen and oxygen in the ratio 1 : 8 by weight.

Carbon dioxide contains carbon and oxygen in the ratio of 12 : 32 or 3 : 8.

Properties of substances-

1) Malleability-

                       When solid is being beaten then it is converted into sheet .This property of solid is called Malleability.

Ex- copper , silver , gold , aluminium and iron are malleable in nature.

2) Ductility-

                        It is the property of metal to be drawn into wires.

Ex- copper , silver , gold , aluminium and iron are ductile in nature.

3) Plasticity-

                          It is the property of solid substances due to which solid does not come back to its original shape, size or volume

after the deforming force is removed.

4) Elasticity-

                          It is the property of solid substances in which solid regain to its original shape, size or volume after the deforming force is removed.

 5) Hygroscopicity-

                        Compounds combine with moisture of atmosphere and get converted into hydroxides or hydrates. Such compounds are called hygroscopic.

Ex- anhy. CuSO4, anhy. FeSO4, anhy. Na2CO3 , quick lime are hygroscopic in nature.

6) Deliquescence-

                      Some compounds absorb moisture of atmosphere and become wet. These compounds are called deliquescent.

Ex- Anhy. MgCl2, Anhy. CaCl2, NaOH and KOH are deliquescent in nature.

7) Efflorescence-

                     Some crystalline solid loses their water of crystallisation on exposure and becomes powdery.Such compounds are called efflorescent.

Ex- Na2CO3.10H2O (washing soda), Na2SO4.10H2O (Glauber’s salt) , K2SO4. Al2(SO4)3. 24 H2O (potash alum) are efflorescent compound.

8) Brittleness-

                      When solid is converted into small pieces on hammering. Then compound is called brittle.

9) Hardness-

                       A material is said to be harder than the other if it can scratch it.Hardness is measured in Moh’s scale.For this purpose , ten materials have been selected and assigned hardness from 1 to 10.

Hardness of talc is minimum but that of diamond is maximum.

Moh’s Scale-

material                   Hardness

Talc                 –            1

Gypsum         –             2

Calcite           –              3

Fluorite        –              4

Apatite .      –               5

Orthoclase feldspar- 6

Quartz          –               7

Topaz           –               8

Corundum   –              9

Diamond     –              10