Covalent bonding model

Molecular substances

molecules are made up of non-metals

properties:

• low melting and boiling points

• non-conductive

• low hardness

covalent bonds

sharing of electrons between non-metals (top right of pt)

• due to simultaneous attraction of two positive nuclei

Inter/Intramolecular forces

Intramolecular: between atoms in a molecule

→ stronger due to electrostatic attraction

→ require large amounts of energy to break

Intermolecular: between molecules of a covalent substance

→ generally weaker

→ broken with small amounts of energy

Linear molecules

molecules with one single bond, and molecules with two double bonds (CO₂)

Bent molecules

two covalent bonds pointing outward next to each other

pyramidal molecules

3 bonding pairs, 1 lone pair

Tetrahedral molecules

All bonding pairs occupied

usually involves carbon

Trigonal planar

e.g. ethene

double bond, 4 single bonds