definitions

Question 1

chemical bonding

Answer 1

The mutual interaction between atoms resulting from the attraction and repulsion between their nuclei and valence electrons.

Question 2

bond energy

Answer 2

The energy needed to break chemical bonds to form neutral atoms.

Question 3

bond length

Answer 3

The average distance between the nuclei of two bonded atoms.

Question 4

ionic bonding

Answer 4

The electrostatic interaction between cations and anions that involves the
transfer of electrons and forms a three-dimensional lattice structure.

Question 5

covalent bonding

Answer 5

The electrostatic interaction that involves the sharing of electrons between atoms to form molecules.

Question 6

dative covalent bonding

Answer 6

A bond that involves the sharing of an electron pair between atoms where both electrons are donated by one of the two atoms.

Question 7

molecule

Answer 7

It is a neutral group of two or more atoms which are bonded together
sufficiently strongly to act as a unit in chemical reactions.

Question 8

bonding pair (shared pair)

Answer 8

It is the pair of electrons that is shared between two atoms in a covalent bond.

Question 9

lone pair

Answer 9

It is a pair of electrons in the valence shell of an atom that is not shared with another atom.

Question 10

electronegativity

Answer 10

It is a measure of the tendency of an atom to attract a shared pair of electrons towards itself.

Question 11

polar covalent bond

Answer 11

A bond that is formed as a result of the unequal sharing of electrons between two atoms.

Question 12

non-polar (pure) covalent bond

Answer 12

The bond that is formed as a result of an equal sharing of electrons between two atoms.

Question 13

the heat of the reaction

Answer 13

is the energy absorbed or released in a chemical reaction?

Question 14

exothermic reactions

Answer 14

are reactions that release energy.

Question 15

endothermic reactions

Answer 15

reactions that absorb energy

Question 16

reversible reaction

Answer 16

a reaction where products can be converted back into reactants.

Question 17

activation energy

Answer 17

the minimum energy needed for a reaction to take place.

Question 18

activated complex

Answer 18

is the unstable transition state from reactants to products in a chemical reaction.

Question 19

intermolecular forces

Answer 19

are the forces of attraction or repulsion between molecules.

Question 20

intramolecular forces

Answer 20

or interatomic forces are the forces between atoms or ‘inside’ molecules which keep atoms together.

Question 21

dipole dipole forces

Answer 21

are the forces between polar molecules.

Question 22

induced dipole forces

Answer 22

or London forces are the forces between non–polar molecules.

Question 23

hydrogen bonds

Answer 23

are the forces between molecules in which a hydrogen atom that is covalently
bonded to a small, highly electronegative atom is attracted to a lone pair of
electrons on an atom in a neighbouring molecule.

Question 24

boiling point

Answer 24

is the constant temperature at which the vapour pressure of a substance equals atmospheric pressure.

Question 25

melting point

Answer 25

is the temperature at which the solid and liquid phases of a substance are at equilibrium.

Question 26

vapour pressure

Answer 26

is the pressure exerted by a vapour at equilibrium with its liquid in a closed system.

Question 27

forces of cohesion

Answer 27

are forces of attraction between molecules of the same substance.

Question 28

forces of adhesion

Answer 28

are forces of attraction between molecules of different substances.

Question 29

capillarity

Answer 29

is the tendency of a liquid to be elevated or depressed in a narrow tube as a result of surface tension.