Question

5. Elements are broadly classified into metals & non-metals. State six general differences physical properties of metals & non-metals. State two metals & two non-metals contradict with the general physical properties - giving reasons. State one difference property between metalloids & noble gases. 6. With reference to elements - define the term 'molecule'. Give two examples each of a monoatomic, diatomic & polyatomic molecule.​

Answer 1

Properties of Metals:

• They are lustrous, i.e. they shine.
• They are malleable, i.e. they can be drawn into sheets.
• They are ductile, i.e. they can be made into wires.
• They are good conductors of heat and electricity.
• They have high density.
• They have high melting and boiling points.

Properties of Non-Metals:

• They are non-lustrous, i.e. they do not shine.
• They are non-malleable, i.e. they cannot be drawn into sheets.
• They are non-ductile, i.e. they cannot be made into wires.
• They are bad conductors of heat and electricity.
• They have low density.
• They have low melting and boiling points.

Metals which contradict general properties of metals:

• Zinc is a metal but it is not malleable and not ductile.
• Mercury is a metal but it is liquid even at room temperature while other metals are generally solid.

Non-metals which contradict general properties of non-metals:

• Iodine is lustrous while non-metals are not lustrous.
• Graphite is a good conductor of electricity, while non-metals are bad conductors of electricity.