Key Definitions 1.2

Question 0

Electron shielding

Answer 0

The repulsion between electrons in different inner shells. Shielding reduces the net attractive force from the positive nucleus on the outer-shell electrons.

Question 1

The first ionisation energy

Answer 1

The energy required to remove one electron from in each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions

Question 2

Successive ionisation energies

Answer 2

A measure of the energy required to remove each electron in turn.

Question 3

A shell

Answer 3

A shell is a group of atomic orbitals with the same principal quantum number, n. Also known as a main energy level.

Question 4

Principal quantum number

Answer 4

n, is a number representing the relative overall energy of each orbital

This increases with distance from the nucleus. The sets of orbitals with the same n-value are referred to as electron shells or orbitals.

Question 5

Atomic orbital

Answer 5

A region within an atom that can hold up to two electrons with opposite spins.

Question 6

Sub-shell

Answer 6

A group of the same type of atomic orbitals within a shell

Question 7

Electron configuration

Answer 7

The arrangement of electrons in an atom.

Question 8

Compound

Answer 8

A substance formed from two or more chemically bonded elements in a fixed ratio.

Question 9

Ionic bond

Answer 9

The electrostatic attraction between oppositely charged ions.

Question 10

Giant ionic lattice

Answer 10

A three-dimensional structure of oppositely charged ions, held together by strong ionic bonds.

Question 11

A group

Answer 11

A vertical column in the periodic table. Elements in the same group have similar chemical properties and their atoms have the same number of electrons on their outer shell.

Question 12

A covalent bond

Answer 12

A bond formed by as haired pair of electrons

Question 13

A lone pair

Answer 13

An outer shell pair of electrons that is not involved in chemical bonding

Question 14

A dative covalent bond

Answer 14

A shared pair of electrons which has been provided by one of the bonding atoms only

Question 15

Electronegativity

Answer 15

A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond

Question 16

Permanent dipole

Answer 16

A small charge difference across a bond that results from a difference in electronegativities of the bonded atoms.

Question 17

Polar covalent bond

Answer 17

A polar covalent bond has a permanent dipole

Question 18

A polar molecule

Answer 18

When the molecule has an overall dipole when you take into account any dipoles across the bond

Question 19

An intermolecular force

Answer 19

An attractive force between neighbouring molecules

Question 20

Permanent dipole-dipole force

Answer 20

A weak attractive force between permanent dipoles is neighbouring molecules

Question 21

Van der Waals’

Answer 21

Attractive forces between induced dipoles in neighbouring molecules

Question 22

Hydrogen bonds

Answer 22

A strong dipole-dipole attraction between an electron deficient hydrogen atom on one molecule and a lone pair on a highly electronegative atom on a different molecule

Question 23

Metallic bonding

Answer 23

The electrostatic attraction between positive metal ions and delocalised electrons

Question 24

Delocalised electrons

Answer 24

Electrons that are shared between more than two atoms

Question 25

A giant metallic lattice

Answer 25

A 3D structure of positive ions and delocalised electrons bonded together by strong metallic bonds.

Question 26

A simple molecular lattice

Answer 26

A 3D structure of molecules, bonded together by weak intermolecular forces

Question 27

A giant covalent lattice

Answer 27

A 3D structure of atoms bonded together by strong covalent bonds