Bonding & Structure

Question 1

Ionic bond

Answer 1

Strong electrostatic attraction between two oppositely charged ions. Strength of
attraction depends on the relative sizes and charges of ions.

Question 2

Cation

Answer 2

A positively charged ion,

Question 3

Anion

Answer 3

A negatively charged ion

Question 4

Isoelectronic species

Answer 4

Chemical species that have the same number of electrons, e.g. N(3−), O(2−), F(−) ions

Question 5

Covalent bond

Answer 5

The strong electrostatic attraction between two nuclei and the shared pair of
electrons between them.

Question 6

𝞼 (sigma) bond

Answer 6

A bond that results from a direct (end-on) overlap of two orbitals

Question 7

π (pi) bond

Answer 7

A bond that is formed when two orbitals overlap sideways,

Question 8

Dative covalent bonding

Answer 8

Occurs when one atom donates both electrons in a bond. e.g. in NH4+ or H3O+ ions. Marked with an arrow.

Question 9

Allotropes

Answer 9

Different forms of the same element, e.g. allotropes of carbon are: diamond, graphite,
graphene, fullerenes, carbon nanotube

Question 10

Malleable

Answer 10

substance can be shaped.

Question 11

Ductile

Answer 11

substance can be drawn into a wire.

Question 12

Intermolecular forces

Answer 12

Forces between the molecules

Question 13

Electronegativity

Answer 13

The ability of atom to attract the bonding electrons in a covalent bond

Question 14

Dipole

Answer 14

Difference in charge between the two atoms of a covalent bond caused by a shift in electron
density in the bond due to the electronegativity difference between elements participating in
bonding

Question 15

Metallic bonding

Answer 15

Strong electrostatic attraction between metal ions and the sea of delocalised
electrons that surround them.

Question 16

Delocalised electron

Answer 16

The electrons that are not contained within a single atom or a covalent bond

Question 17

Bond length

Answer 17

Internuclear distance between two covalently bonded atoms

Question 18

London forces

Answer 18

Weak intermolecular forces arising due to fluctuations of electron density within a
nonpolar molecule. These fluctuations may temporarily cause the asymmetric electron distribution :
the molecule becomes an instantaneous dipole

Question 19

Permanent dipole-dipole interactions

Answer 19

Dipole-dipole attractions between polar molecules. Stronger

than London forces.

Question 20

Hydrogen bond

Answer 20

A type of intermolecular force (with some bonding character) between a hydrogen
bonded to a more electronegative atom than hydrogen (usually N,O,F) and other atom in a
same/different molecule. Directional nature - the bond angle is often 180°. Responsible for
anomalous properties of water, e.g. the density of ice < density of water. Ice occupies greater
volume than water due to the directional nature of hydrogen bonds within the solid structure.