CBSE Metals and Nonmetals for (2009-2010) Subject Notes

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Metals and Nonmetals for (2009-2010)

Metals and Nonmetals for (2009-2010)

Metals The elements that lose electrons and form positive ions are called metals. They are also called electropositive elements. E.g. sodium, potassium, calcium, magnesium, gold, silver, copper, etc.

Hydrogen is a nonmetal but it is placed in the in the group of metals because like metals it also loses electron and forms positive ion.

Physical properties of metals

Metals are malleable, ductile, hard, good conductors of heat and electricity, and sonorous. They are generally solids and have high melting and boiling points.

Chemical properties of metals.

1. Metals on burning in air forms basic oxides.
2. Metals displace hydrogen from water and steam.
3. Metals displace hydrogen from dilute acids.
4. Metals form ionic chlorides with chlorine.
5. Metals do not react with hydrogen. ( only few reactive metals react with hydrogen to form hydrides )

Nonmetals The elements that gain electrons and form negative ions are called nonmetals. They are also called electronegative elements. E.g. chlorine, sulphur, oxygen, bromine, phosphorus, nitrogen, etc.

Physical properties of metals

1. Nonmetals are not malleable and ductile but they are brittle.
2. Nonmetals are solid, liquid and gas at room temperature.
3. Nonmetals are not good conductors of heat and electricity.
4. Nonmetals have low melting and boiling points.
5. Nonmetals are soft.

Chemical properties of metals

1. Nonmetals form acidic or neutral oxides when react with air.
2. Nonmetals do not react with water and steam.
3. Nonmetals do not displace hydrogen with dilute acids.
4. Nonmetals form covalent chlorides with chlorine.
5. Nonmetals react with hydrogen to form stable hydrides.

Lusture The property of an element due to which it has a shiny appearance is called metallic lusture.

Malleability The property of metals to be beaten into thin sheets is called malleability. Gold and silver are most malleable metals.

Ductility The property of metals to be drawn into thin wires is called ductility. Gold is most ductile metal.

Allotropy and allotropes The phenomenon in which an element can exist in two or more different physical forms is called allotropy and the different physical forms of an element are called allotropes.

Allotropes of carbon are graphite, diamond and Buckminster fullerene.
Allotropes of sulphur are monoclinic sulphur and rhombic sulphur.