[🧪] Definitions

Question 1

Define:

first ionisation energy

Answer 1

The amount of energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of uni-positive ions.

Question 2

Define:

isotope

Answer 2

An atom of the same element with the same number of protons but different number of neutrons.

Question 3

Define:

unified atomic mass unit

Answer 3

One twelfth of the mass of a C₁₂ atom

Question 4

Define:

relative atomic mass

Answer 4

the average mass of an atom of an element compared to one twelfth of the mass of a C₁₂ atom.

Question 5

Define:

relative isotopic mass

Answer 5

The mass of an isotope of an element compared to one twelfth of the mass of a C₁₂ atom.

Question 6

Define:

relative molecular mass

Answer 6

The sum of the relative atomic masses of each atom in a molecule.

Question 7

Define:

relative formula mass

Answer 7

The sum of the relative atomic masses of each ion in the formula of an ionic compound compared to one twelfth of the mass of a C₁₂ atom.

Question 8

Define:

mole

Answer 8

A mole of a substance is one Avogadro’s constant of particles in the substance.

Question 9

Define

atomic orbitals

Answer 9

regions of space outside the nucleus that can be occupied by a maximum of two electrons

Question 10

Define

covalent atomic radius

Answer 10

half the distance between two nuclei of covalently bonded atoms of the same type

Question 11

Define

bond energy

Answer 11

the energy required to break one mole of a particular covalent bond in the gaseous state

Question 12

Define:

bond length

Answer 12

the internuclear distance of two covalently bonded atoms

Question 13

Define:

bond polarity

Answer 13

the partial separation of charge when two different atoms are joined by a covalent bond

Question 14

free radical

Answer 14

a species with one or more unpaired electrons

Question 15

Define:

covalent bond

Answer 15

The electrostatic forces of attraction between the nuclei of two atoms and a shared pair of electrons

Question 16

Define:

ionic bond

Answer 16

The electrostatic forces of attraction between oppositely charged ions.

Question 17

Define:

metallic bond

Answer 17

the electrostatic forces of attraction between positive metal ions and delocalised electrons

Question 18

Define:

electronegativity

Answer 18

the power of an atom to attract electrons towards itself

Question 19

Standard enthalpy change of reaction

Answer 19

the amount of heat energy released or absorbed when one mole of a substance is formed or reacted in a chemical reaction under standard conditions

Question 20

Standard enthalpy change of formation

Answer 20

the enthalpy change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions

Question 21

Standard enthalpy change of combustion

Answer 21

the amount of energy released when one mole of a substance is completely burned in excess oxygen under standard conditions

Question 22

Define

transition state

Answer 22

the stage in a reaction at which chemical bonds are partially broken and formed

Question 23

Define

average bond enthalpy

Answer 23

the energy needed to break one mole of bonds in a gaseous molecule averaged over similar compounds

Question 24

Define

disproportionation reaction

Answer 24

A disproportionation reaction is a type of redox reaction where a species is simultaneously oxidised and reduced