The elements which have a tendency to form positive ions are known metals. The elements which have a tendency to form negative ions are known non-metals. The elements whose properties fall between those of metals and non-metals ore known metalloids.
Metals
Metals in their pure state, have metallic lustre.
Metals are generally hard.
• Some metals can be beaten into thin sheets. This property is called f malleability. ⚫ Metals are ductile, ie, thin wires can be drawn from metals. • Metals are good conductor of heat and electricity and have high melting points. Silver and copper are the best conductor of heat.
Metals are solid but mercury is liquid at room temperature.
. Their oxides are basic.
With dil. HCl or H,SO,, they release H₂ gas. e.g., aluminium, copper, sodium, etc
Non-metals
. These can be solid, liquid or gas at room temperature. . These are neither malleable nor ductile. These are brittle.
These do not conduct heat and electricity. C (graphite) is good conductor of electricity.
. These are not lustrous
Iodine is non-metal but have lustrous appearance. Non-metals are generally soft.
They have comparatively low melting and boiling points. Their oxides are acidic.
e.g., oxygen, nitrogen, etc.