Definitions IGCSE Chemistry

Question 1

proton number

Answer 1

the number of protons in the nucleus of an atom

Question 2

nucleon number

Answer 2

the total number of protons and neutrons in the nucleus of an atom

Question 3

isotopes

Answer 3

atoms of the same element which have the same proton number but a different nucleon number

Question 4

relative atomic mass

Answer 4

the average mass of naturally occurring atoms of an element on a scale where the C12 atom has a mass of exactly 12 units

Question 5

relative molecular mass

Answer 5

the sum of the relative atomic masses

Question 6

mole

Answer 6

a mole of a substance is the amount that contains the same number of units as the number of carbon atoms in 12 grams of carbon-12

Question 7

avogadro constant

Answer 7

6.02 x 10^23

Question 8

electrolysis

Answer 8

the breakdown of an ionic compound, molten or in aqueous solution, by the passage of electricity

Question 9

oxidation

Answer 9

when a substance gains oxygen, loses electrons, or the oxidation state of the substance is increased

Question 10

reduction

Answer 10

when a substance loses oxygen, gains electrons or the oxidation state of the substance is decreased

Question 11

redox

Answer 11

-

Question 12

oxidising agent

Answer 12

a substance which oxidises another substance during a redox reaction

Question 13

reducing agent

Answer 13

a substance which reduces another substance during a redox reaction

Question 14

acids

Answer 14

substances that proton donors and have a pH value below 7

Question 15

bases

Answer 15

substances that are proton acceptors and have a pH value above 7

Question 16

polymers

Answer 16

large molecules built up from small units (monomers)