A shared pair of electrons which has been provided by one of the bonding atoms.
Covalent Bond
A bond formed by a shared pair of electrons
Delocalised Electrons
Electrons that are shared between more than two atoms
Electron Configuration
The arrangement of electrons in an atom
Electronegativity
A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond
Electron Shielding
The repulsion between electrons in different inner shells. Shielding reduces the net attractive force from the positive nucleus on the outer-shell of electrons.
Giant Covalent Lattice
A 3-D structure of atoms bonded together by strong covalent bonds
Giant Ionic Lattice
A 3-D structure of oppositely charged ions bonded together by strong ionic bonds
Giant Metallic Lattice
A 3-D structure of positive ions and delocalised electrons bonded together by strong metallic bonds.
Group
A vertical column in the Periodic Table. Elements in a group have similar properties and their atoms have the same number of outer electrons
Hydrogen Bond
A strong dipole-dipole attraction between an electron-deficient hydrogen atom on one molecule and a lone pair of electrons on a highly electronegative atom on a different molecule
Intermolecular Force
An attractive force between neighboring molecules. Intermolecular force can be van der Waals' forces, permanent dipole-dipole forces or hydrogen bond.
Ion
A positively or negatively atom or group of atoms
Ionic Bond
The electrostatic attraction between oppositely charged ions
First Ionisation Energy
The energy required to remove one electron from each atom in on mole of gaseous atoms to form on mole of gaseous 1+ ions
Lone Pair
An outer shell pair of electrons that is not involved in chemical bonding
Metallic Bonding
The electrostatic attraction between positive metal ions and delocalised electrons
Period
A horizontal row of elements in the Periodic Table. Elements show trends in properties across period
Permanent Dipole
A small charge difference across a bond resulting from a difference in electronegativities of the bonded atoms.
Permanent dipole-dipole force
A attractive force between permanent dipoles in neighboring polar molecules
Polar Covalent Bond
A bond with a permanent dipole
Polar molecule
A molecule with an overall dipole taking into account any dipoles across bonds.
Principal quantum number, n
A number representing the relative overall energy of each orbital, which increases with distance from the nucleus. The sets of orbitals with the same n value are referred to as electron shells or energy levels
Salt
A chemical compound formed from an acid, when a H+ ion from the acid has been replaced by a metal ion or another positive ion
Shell
A group of atomic orbitals with the same principle quantum number n. Also known as a main energy level.
Simple molecular lattice
A 3-D structure of molecules bonded together by weak intermolecular forces
Sub-shell
A group of the same type of atomic orbitals within a shell
Van der Waals' forces
Very weak attractive forces between induced dipoles in neighboring molecules
Water of Crystallisation
Water molecules that form an essential part of the crystalline structure of a compound
Atomic Orbital
A region within a atom that can hold up to two electrons with opposite spins