Atomic Structure

Question 1

Describe the plum pudding model

Answer 1

Scientists suggested the plum-pudding model for the structure of atoms. An atom is a ball of positive charge with negative electrons embedded in it

Question 2

Describe alpha scattering experiment

Answer 2

Alpha particles were fired at a sheet of gold.
Most of the alpha particles went straight through the gold foil. Therefore atoms are mainly empty space.
However, some of the alpha particles were deflected(changed direction) therefore the centre of an atom must have a positive charge and that repelled the alpha particles.
Sometimes an alpha particles bounced straight back. The mass of the atom must be concentrated in the centre. We now call the central part of an atom the nucleus

Question 3

What did the alpha scattering expirement lead to and describe this

Answer 3

The nuclear model - lots of empty space, positive nucleus in the centre containing almost all the mass, and around the edge all the negative electrons

Question 4

What did Niels Bohr propose

Answer 4

Electrons orbit the nucleus at specific distances. Bohr’s work agreed with the results of experiments by other scientists. We now call the ‘orbits’ energy levels or shells

Question 5

Who discovered neutrons

Answer 5

James Chadwick