atomic theory

Question 1

John Dalton

Answer 1

(1803)
- Atoms are indivisible
- all atoms are identical in mass
- atoms combine to form compounds
- chemical reactions involve arranging atoms

Question 2

Joseph John Thompson

Answer 2

(1897)
- discovery of an electron
- atoms were a sphere of positive charge with electrons inside like plum pudding
- discovery of ions

Question 3

Ernest Rutherford (1910)

Answer 3

(1910)
- gold foil experiment proves a small dense positively charged nucleus
- electrons orbit nucleus like the sun
- discovery of proton
- hypothesis of the neutron

Question 4

Neils Bohr

Answer 4

(1910)
- electrons occupy energy levels or shells
- move between electron shells

Question 5

James Chadwick

Answer 5

(1932)
- discovery of the neutron in nucleus

Question 6

Gold Foil experiment

Answer 6

Ernest Rutherford
Fired a beam of alpha particles at a thing sheet of gold
Most particles passed through and some deflected.
Mostly empty space in atom and most of the mass and its positive charge is located in a tiny central region

Question 7

Cathode-ray tube

Answer 7

vacuum tube containing one or more electron guns which emit electron beams that are manipulated to display image on a phosphorescent screen - helped discover all atoms contain tiny negatively charged subatomic particles or electrons.