Chemical Changes and Structures

Question 1

acid

Answer 1

a substance that produces hydrogen ions (H+) when dissolved in water

Question 2

alkali

Answer 2

a soluble base that produced hydroxide ions (OH-) when dissolved in water

Question 3

atom

Answer 3

the smallest quantity of an element. contains protons, neutrons and electrons.

Question 4

atomic number

Answer 4

the number of protons in the nucleus of an atom of an element

Question 5

base

Answer 5

a substance that will neutralise an acid

Question 6

catalyst

Answer 6

a substance that will speed up a chemical reaction but is not used up in the process

Question 7

compound

Answer 7

a substance made up of two or more elements chemically joined

Question 8

concentration

Answer 8

a measure of how much solute is dissolve in a solvent, measured in mol l-1

Question 9

covalent bond

Answer 9

a shared pair of electrons between (usually) two non-metal atoms

Question 10

covalent network

Answer 10

a giant network of non-metal atoms held together by covalent bonds

Question 11

dilution

Answer 11

addition of more solvent to a solution to decrease its concentration

Question 12

dissociation

Answer 12

a procress in which compounds separate into oppositely charged ion

Question 13

electron

Answer 13

a negatively charged particle with a relative mass of zero, which orbits the nucleus of an atom

Question 14

element

Answer 14

a substance that consists of only one type of atom

Question 15

enzyme

Answer 15

a biological catalyst

Question 16

group ion

Answer 16

a charged particle that contains more than one type of atom (such as permanganate, MnO₄⁻)

Question 17

indicator

Answer 17

a substance whose colour changes depending on pH

Question 18

ion

Answer 18

a charged particle

Question 19

ionic bond

Answer 19

the electrostatic force of attraction between positive ions and negative ions

Question 20

ionic lattice

Answer 20

a large arrangement of ions held together by ionic bonds

Question 21

isotopes

Answer 21

atoms with the same atomic number but different mass numbers

Question 22

mass number

Answer 22

equal to the number of protons plus neutrons in an atom or ion

Question 23

molecule

Answer 23

two or more atoms held together by covalent bonds

Question 24

neutralisation

Answer 24

a reaction in which the pH moves towards 7

Question 25

neutron

Answer 25

a neutral particle with a relative mass of 1 found in the nucleus of an atom

Question 26

nucleus

Answer 26

the positively charged centre of an atom which contains the neutrons and protons

Question 27

pH

Answer 27

a measure of how acidic or alkaline a substance is

Question 28

proton

Answer 28

a positively charged particle with a relative mass of 1 found in the nucleus of an atom

Question 29

rate

Answer 29

a measure of how quickly a chemical reaction is progressing

Question 30

relative atomic mass (RAM)

Answer 30

the average mass of the isotopes of an element

Question 31

gram formula mass (GFM)

Answer 31

the mass of one mole of a substance expressed in grams

Question 32

spectator ion

Answer 32

an ion that is present as both a reactant and a product in a chemical equation, and takes no part in the reaction

Question 33

tetrahedral

Answer 33

describes the shape of a molecule with a central atom bonded to four other atoms

Question 34

valency

Answer 34

the number of bonds that an atom or ion can form

Question 35

salt

Answer 35

the substance formed when the hydrogen ion in a salt is replaced by a metal ion or the ammonium ion