Famous People

Question 1

Dalton (1808)

Answer 1

scientific theory that:
1. matter is made up of tiny, indivisible particles called atoms
2. All atoms of a specific elements have the same properties
3. atoms can’t be created or destroyed
4. atoms of different elements can be combined in fixed ratios to form compounds
5. atoms can be rearranged, combined or separated in chemical reactions

Question 2

JJ Thomson (1897)

Answer 2

showed that all atoms contain tiny negatively charged particles called electrons by observing cathode rays from high voltage electrodes
displayed in the plum pudding model

Question 3

Rutherford (1910/1920)

Answer 3

found that all atoms are mostly empty space with most mass concentrated in the nucleus, also discovered that uranium emits alpha and beta radiation

Question 4

Chadwick (1932)

Answer 4

found that atomic nuclei contain uncharged particles called neutrons

Question 5

Bohr

Answer 5

proposed a model of the atom in which electrons can only occupy certain orbits around the nucleus that all have the same energy. further from nucleus -> higher energy, return to lower energy -> emit light

Question 6

Schroedinger

Answer 6

proposed that electrons follow orbitals (electron clouds), where electrons are most likely to be, rather than clearly defined orbits