C1.2 Atomic structure

Question 1

What are atoms?

Answer 1

An atom is the smallest particle of an element that still has its chemical properties
- Different elements are made from different atoms

Question 2

What are molecules?

Answer 2

• A molecule is made from 2 or more atoms joined together
• They are joined by attractive forces called chemical bonds
• Remember that molecules have different chemical and physical properties from the atoms they contain

Question 3

What is the size of an atom given by?

Answer 3

The size of an atom is given by its atomic radius

Question 4

What is a bond length?

Answer 4

Is the distance between the centres of 2 joined atoms

Question 5

What is inside an atom?

Answer 5

• While the inside of an atom is mostly empty space it does contain 3 even smaller subatomic particles
• Protons and neutrons joined together as the nucleus at the centre
• Electrons surrounding the nucleus in shells

Question 6

What is the radius of a nucleus relative to the radius of atom?

Answer 6

About 100,000 times less

Question 7

What does the full chemical symbol show?

Answer 7

• Bottom number is the atomic number = number of protons
• Every atom has equal number of protons and electrons
• Top number is element’s mass number = number of protons + number of neutrons

Question 8

What are isotopes?

Answer 8

• Isotopes of an element are atoms with the same number of protons and electrons but different number of neutrons
• This means that isotopes have the same atomic number but their mass number is different
• You should identify isotopes using their full chemical symbols but may see isotopes named after their mass number

Question 9

What are isotopes like?

Answer 9

• The chemical properties of an element depend on the number of electrons in its atoms
• All the isotopes of an element have the same number of electrons so they have identical chemical properties
• However the different number of neutrons may affect their physical properties

Question 10

What are ions?

Answer 10

• Ions are charged particles
• They are formed when atoms or groups of atoms lose or gain electrons
• This can happen during chemical reactions
• Only the number of electrons changes when an atom becomes an ion.