Metals and Non-metals

Properties of some metals

 The above activity shows that metals are good conductors of heat and have high melting points. 

The best  conductors of heat are silver and copper. 

Lead and mercury are comparatively poor conductors of heat.

Also read : STRUCTURE OF THE ATOM

 The metals that produce a sound on striking a hard surface are said to be sonorous

All metals except mercury exist as solids at room temperature.

Iodine is a non-metal but it is lustrous.

 ( Carbon is a non-metal that can exist in different forms. Each form is called an allotrope.

Diamond, an allotrope of carbon, is the hardest natural substance known and has a very high melting and boiling point. 

Also read :ATOMS AND MOLECULES

Graphite, another allotrope of carbon, is a conductor of electricity.

Alkali metals (lithium, sodium, potassium) are so soft that they can be cut with a knife. They have low densities and low melting points.

 Metals such as potassium and sodium react so vigorously that they catch fire if kept in the open. 

Hence, to protect them and to prevent accidental fires, they are kept immersed in kerosene oil.

 At ordinary temperature, the surfaces of metals such as magnesium, aluminium, zinc, lead, etc., are covered with a thin layer of oxide. 

Also read : IS MATTER AROUND US PURE

The protective oxide layer prevents the metal from further oxidation.

Iron does not burn on heating but iron filings burn vigorously when sprinkled in the flame of the burner.

Copper does not burn, but the hot metal is coated with a black coloured layer of copper oxide.

Silver and gold do not react with oxygen even at high temperature

Anodising is a process of forming a thick oxide layer of aluminium. 

Also read :MATTER IN OUR SURROUNDINGS

Aluminium develops a thin oxide layer when exposed to air. 

This aluminium oxide coat makes it resistant to further corrosion

Aqua regia,

 ( is a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3:1.

 It can dissolve gold, even though neither of these acids can do so alone.

 Aqua regia is a highly corrosive, fuming liquid. It is one of the few reagents that is able to dissolve gold and platinum