2.2. Electrons, Bonding and Structure: Module 2: Foundations In Chemistry: Chemistry OCR A A Level

Ionic bonding

Ionic bonding is an electrostatic attraction between positive and negative ions.

Physical properties

Physical properties of a substance include the boiling point, melting point, solubility and conductivity. These properties are different depending on the type of bonding and the crystal structure of the compound.

Covalent bond

A covalent bond is the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.

Dative

Dative or coordinate bonds form when both of the electrons in the shared pair are supplied from a single atom. It is indicated using an arrow from the lone electron pair.

Pauling electronegativity values

Pauling electronegativity values can be used to compare the electronegativity of atoms. A higher value on the pauling scale indicates a greater electronegativity.

Induced dipole

An induced dipole can form when the electron orbitals around a molecule are influenced by the distributions of electrons on another particle.

Van der Waals Forces

Van der Waals forces are the weakest type of intermolecular force. They act as an induced dipole between molecules.

Permanent Dipole

Permanent dipoles are a type of intermolecular force which acts between molecules with a polar bond.

Hydrogen bonds

Hydrogen bonds are the strongest type of intermolecular forces. Hydrogen bonds only act between hydrogen and the three most electronegative atoms: nitrogen, oxygen and fluorine.

Graphite

Graphite is a macromolecular structure made up of carbon atoms. However, in graphite, each carbon atom is bonded to three others in flat sheets.

Graphene

Graphene is a relatively recent material consisting of single, 2D sheets of graphite that are just one atom thick.