1 - Chemical Quantities

Question 1

Elements

Answer 1

The simplest chemicals - they cannot be broken down into simpler chemicals.

Question 2

Compounds

Answer 2

Chemicals containing two or more elements chemically combined together.

Question 3

Atom

Answer 3

The smallest particle of an element.

Question 4

Molecule

Answer 4

A particle containing two or more atoms joined together chemically.

Question 5

Ion

Answer 5

An atom, or a group of atoms, which has become electrically charged by the loss or gain of one or more electrons.

Question 6

Molecular Formula

Answer 6

Shows the number of atoms of the different elements in one molecule of a compound.

Question 7

Empirical Formula

Answer 7

Shows the simplest whole number ratio of the atoms of different elements in a compound.

Question 8

Spectator Ions

Answer 8

Ions which take no part in a reaction.

Question 9

Acids

Answer 9

Substances which donate hydrogen ions.

Question 10

Bases

Answer 10

Substances which accept hydrogen ions.

Question 11

Alkalis

Answer 11

Soluble bases.

Question 12

Salts

Answer 12

Ionic compounds formed when an acid reacts with a base.

Question 13

Relative molecular mass

Answer 13

The sum of the relative atomic masses of all the atoms in the molecular formula.

Question 14

Relative formula mass

Answer 14

The sum of the relative atomic masses of all the atoms in the formula.

Question 15

Molar mass

Answer 15

The mass of one mole of a chemical (g/mol).

Question 16

Avogadro Constant

Answer 16

The number of atoms, molecules or formula units in one mole of any substance. It is 6.02 x 10^23.

Question 17

Molar volume

Answer 17

The volume of 1 mole of a gas. At room temperature and pressure it is 24 dm^3/mol.

Question 18

Actual yield

Answer 18

The mass of product obtained.

Question 19

Theoretical yield

Answer 19

The mass of product obtained if the reaction goes according to the equation.

Question 20

Percentage yield

Answer 20

(Actual yield / theoretical yield) x 100

Question 21

Limiting reactant

Answer 21

A substance which is present in an amount which limits the theoretical yield.

Question 22

Atom Economy

Answer 22

(Mass of atoms in desired product / mass of atoms in all reactants) x 100