History of Atom

Question 1

Plum Pudding Model

Answer 1

> Electrons randomly distributed amongst positively charged mass
No neutrons
– J.J. Thompson

Question 2

Rutherford’s gold leaf experiment (info)

Answer 2

1911 > Rutherford supervised Geiger and Marsden

Question 3

Rutherford’s gold leaf experiment (hypothesis)

Answer 3

Alpha particles would deflect or be absorbed as plum pudding model belief thought atoms were solid

Question 4

Rutherford’s gold leaf experiment (summary)

Answer 4

In a circular detector (for alpha particles) is a sheet of gold leaf (foil) > 1 atom thick ish an alpha source fired alpha particles at the gold leaf

Question 5

Rutherford’s gold leaf experiment (observations and consequences)

Answer 5

> Most Alpha went straight through > Most of the atom is empty space
A small number were deflected > Nucleus is very small – deflection = repulsion so nucleus is also positive (we knew alpha particles were positive) -electrostatic repulsion

Question 6

Chadwick discovered

Answer 6

within the nucleus there were neutrons

Question 7

Bohr discovered

Answer 7

electrons orbit the nucleus in discrete energy levels (shells)