1) Review of basic concepts

Question 1

Pure substance

Answer 1

A substance not contaminated by any other substances. It is pure if its properties do not change after undergoing purification procedures

Question 2

Impure substance

Answer 2

One substance contaminated with small amounts of one or more other substances; is therefore a mixture

Question 3

Mixture

Answer 3

A substance formed by physically combining two or more substances, where each retains its individual properties and can be physcially separated

Question 4

Homogenous

Answer 4

of uniform composition throughout

Question 5

Heterogenous

Answer 5

having non-uniform composition, where we can recognise small pieces of material that are different from other pieces

Question 6

Element

Answer 6

a pure substance consisting of one type of atom

Question 7

Compound

Answer 7

a pure substance made up of two or more elements that are chemically bound together in a fixed ratio

Question 8

Matter

Answer 8

anything that occupies space and has mass

Question 9

States of matter (phases)

Answer 9

physical states - solid, liquid, or gas

Question 10

Properties of a solid (3)

Answer 10

1. Has a definite volume
2. Has a definite shape (eg Cu), or is made up of small pieces that have a definite shape (eg salt)
3. Is difficult to compress

Question 11

Properties of a liquid

Answer 11

1. Has a definite volume
2. Takes the shape of the container it is placed in
3. Is difficult to compress

Question 12

Properties of a gas

Answer 12

1. Expands to fill the volume available to it
2. Takes the shape of the container it is placed in
3. Is easily compressed

Question 13

Melting / fusion

Answer 13

change of a solid to a liquid

Question 14

Freezing / solidifcation

Answer 14

change of a liquid to a solid

Question 15

Boiling

Answer 15

process where a liquid changes to a gas / vapour with the formation of bubbles of vapour throughout the liquid

Question 16

Evaporation / vapourisation

Answer 16

change of liquid to a gas / vapour without the formation of any visible bubbles. It is a much slower process than boiling and can occur at temperatures much lower than the ones at which boiling occurs

Question 17

Condensation / liquefaction

Answer 17

change of a gas / vapour to a liquid

Question 18

Sublimation

Answer 18

change of a solid to a gas without passing through the liquid phase. When dry ice is warmed, it sublimes: the white solid changes directly to a colourless gas

Question 19

Solution

Answer 19

homogeneous mixture where the dispersed particles (molecular or ions) are so small that they never settle out and cannot be seen by a microscope. There is always a solute and a solvent

Question 20

Solute

Answer 20

the substance that is dissolved in a solution

Question 21

Solvent

Answer 21

the liquid that does the dissolving in a solution

Question 22

Suspension (in a solution)

Answer 22

heterogeneous mixture where solid particles are dispersed throughout a liquid but do not dissolve, instead remaining suspended and visible

Question 23

Atom

Answer 23

the smallest unit into which matter can be divided without the release of electrically charged particles. It also is the smallest unit of matter that has the characteristic properties of a chemical element

Question 24

Molecule

Answer 24

two or more atoms connected by chemical bonds, which form the smallest unit of a substance that retains the composition and properties of that substance

Question 25

Diatomic molecule

Answer 25

any chemical compound that is made up of only two atoms

Question 26

Monatomic molecule

Answer 26

A molecule composed of just one atom, and lacks covalent bonds

Question 27

Ion

Answer 27

an atom or molecule with a net electric charge due to the loss or gain of one or more electrons

Question 28

Cation

Answer 28

positively charged ions. commonly metals

Question 29

Anion

Answer 29

negatively charged ions. commonly non-metals

Question 30

Ionic lattice

Answer 30

an evenly distributed crystalline structure; orderly array of positive and negative ions Strong electrostatic forces apply between oppositely charged ions in the lattice structure

Question 31

Subscript

Answer 31

number that refers to the element immediately preceding it

Question 32

The formula of a compound that is made up of ions

Answer 32

a combination of symbols of the elements in the compound, with subscripts denoting how many atoms of each element are in the molecule

Question 33

Formulae

Answer 33

Combinations of symbols used to denote elements