Covalent Substances

Chapter 3

What is covalent bonding

occurs when non metallic elements are shared, to produce a full outer shell

Covalent molecule property

does not conduct electricity- no free moving electrons

low mp and bp- not a strong structure

Covalent layers property

Example- graphite (1 carbon to 3 carbons)

hard in one direction but slippery/soft in the other

can conduct electricity- has free moving electrons between layers

Can be used as a lubricant- the weak dispersion forces slide over each other, reducing friction

covalent network property

example= diamond (1 carbon to 4 carbons)

very hard - no weak forces, only strong meaning everything is in fixed positions

sublimes

cannot conduct electricity- because electrons are shared and there are no free moving electrons

High MP- strong forces

brittle- due to hardness, they break rather than bend

Polar

asymmetrical= uneven charges

non polar

symmetrical= no uneven charges

Dispersion forces

present in polar and non polar

the only one present in non polar molecules (symmetrical)

weakest force

increases as size increases

Dipole dipole

only between polar molecules (asymmetrical)

attraction of -ve and +ve.

larger polarity=stronger dipole dipole interaction

hydrogen bonding

special dipole dipole

when hydrogen bonds with fluorine, nitrogen, oxygen

strongest