C3. Atoms, Elements & Compounds

Question 1

Proton number (atomic number)

Answer 1

The number of protons in the nucleus of an atom

Question 2

Nucleon number (mass 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

Uses of radioactive isotopes

Answer 4

1. To check for oil/gas leaks (sodium-24)
2. To treat cancer patients (cobalt-60)
3. To kill bacteria (cobalt-60/caesium-137)

Question 5

Element

Answer 5

A substance made of atoms with the same atomic number

Question 6

Compound

Answer 6

A substance in which two or more elements are chemically combined

Question 7

Mixture

Answer 7

A mixture contains two or more substances that are not chemically combined

Question 8

Alloy

Answer 8

A mixture of metal with other elements

Question 9

General properties of metals

Answer 9

1. Good conductors of electricity and heat
2. High MP and BP
3. Hard, strong, do not shatter
4. Malleable and ductile
5. Shiny (when polished)
6. Sonorous
7. High density
8. Form positive ions
9. React with oxygen to form oxides that are bases
10. 3 are magnetic (iron, nickel, cobalt)

Question 10

Structure of ionic compounds

Answer 10

A lattice (regular arrangement) of alternating positive and negative ions

Question 11

Allotropes

Answer 11

Different forms of the same element in the same physical state

Question 12

Metallic bonding

Answer 12

A lattice of positive (metal) ions in a ‘sea’ of electrons

Question 13

Molecule

Answer 13

Two or more atoms combined