CC3A Structure of an atom

Question 1

What are the three ideas in John Daltons theory about the atom

Answer 1

Atoms cannot be created divided or destroyed

Atoms of the same element are exactly the same and atoms of different elements are different

Atoms join with other atoms to make a new substance

Question 2

What discovery caused the original Dalton model of an atom to change

Answer 2

The discovery of subatomic particles

Question 3

Describe the atomic model proposed by JJ Thomson

Answer 3

Plum pudding model

Negatively charged electrons scattered through a positively charged material

Question 4

Describe the structure of an atom

Answer 4

Small central nucleus made up of protons and neutrons

Electrons orbits (move around) the nucleus in shells

Question 5

What is the radius of the nucleus? How large is it compared to the radius atom

Answer 5

The radius of the nucleus is 1x10powerof-14 m.
This is 1/10000 of the atomic radius

Question 6

What are the relative charges of protons, neutrons and electrons

Answer 6

Proton: +1 (positive)
Neutron: 0 (neutral )
Electron: -1 (negative)

Question 7

What are the relative masses of protons, neutrons and electrons

Answer 7

Proton - 1

Neutron - 1

Electron - 1/1835

Question 8

Why do atoms contain equal number of protons and electrons

Answer 8

Atoms are stable with no overall charge

Protons are negatively charged and electrons are negatively charged. For the charges to balance, the number of protons and electrons must be equal

Question 9

Where is the mass of an atom concentrated

Answer 9

Nucleus