Unit 1 Definitions

Question 1

Define: Isotope

Answer 1

Atoms of the same element, with a different number of neutrons

Question 2

Define: Ion

Answer 2

+ve or -ve charged atom or group of atoms

Question 3

Define: Relative isotopic mass

Answer 3

The mass of an isotope of an atom compared to 1/12 of the mass of an atom of carbon-12

Question 4

Define: Relative atomic mass

And similarly, relative molecular mass and relative formula mass.

Answer 4

The weighted mean mass of an atom (molecule/formula unit) compared with1/12 of the mass of an atom of carbon-12

Question 5

Define: Avogadro’s constant

Answer 5

The number of atoms per mole of the carbon-12 isotope (6.02x10^23 mol^-1)

Question 6

Define: A mole

Answer 6

The amount of a substance containing as many particles as there are carbon atoms in 12g of carbon-12

Question 7

Define: Amount of a substance

Answer 7

Is the quantity whose unit is the mole.

Question 8

Define: Molar mass

Answer 8

The mass per mole of a substance

Question 9

Define: Empirical formula

Answer 9

The simplest whole number ratio of atoms of each element in a compound.

Question 10

Define: Molecular formula

Answer 10

The actual number of atoms of each element in a molecule

Question 11

Define: Acid

Answer 11

An acid is a proton donar. E.g. HCl, sulfuric acid (H2SO4) and nitric acid (HNO3)

Question 12

Define: Base

Answer 12

Big dirty stinking proton receiver. E.g. metal oxides, metal hydroxides, ammonia

Question 13

Define: Alkali

Answer 13

A base which dissolves in water to release OH- ions in an aqueous solution

Question 14

Define: Salt

Answer 14

When the H+ ion of an acid is replaced by a metal ion or NH4+

Question 15

Define: First ionisation energy

Answer 15

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

Question 16

Define: Successive ionisation energy

Answer 16

The measure of energy required to remove each electron in turn.

Question 17

Define: Ionic bonding

Answer 17

The electrostatic attraction between oppositely charged ions

Question 18

Define: Covalent bonding

Answer 18

A shared pair of electrons

Question 19

Define: Electronegativity

Answer 19

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

Question 20

Define: Metalic bonding

Answer 20

The attraction of +ve ions to delocalised electrons

Question 21

Define: Periodicity

Answer 21

A repeating pattern across a period

Question 22

Define: Disproportionation

Answer 22

A reaction in which an element is simultaneously oxidised and reduced