Important Points and Formulas of class 7 Science Chapter-Metal and Non-Metals

soil as nitrogen compounds

proteins, carbohydrates, fats and in air as carbon dioxide

Exceptions: Hg and Ga are liquids

Exception: Some of the solid non-metals are

C, S, P, I2 and bromine is a liquid non-metal.

Exceptions: Na, K, Hg have low melting

points and boiling points. Ga has

low melting point but high boiling point.

Exceptions: C, Si and B have high

melting points and boiling points.

Exceptions: Na and K are soft.

Dimond is the hardest naturally

occurring substance.

Exception: Li, Na and K have

density lower than water (1 gm/cm3)

Exception: Diamond

Exceptions: Bi and W are poor

conductors of electricity.

Exception: Graphite and gas carbon

are good conductors of electricity.

Exceptions: I2 and graphite.

Exception: Zn has very less tensile strength.

Exception:Carbon fibre, a recently

developed allotrope of carbon.

Exception: Zinc is not malleable and ductile.

Exception: Carbon fibres are ductile