1.1 Flashcards
1
Q
relative mass for a proton, neutron and electron?
A
proton: 1
Electron:1
Neutron:1/1836
2
Q
relative charge for proton, electron and neutron?
A
proton: +1
Electron: -1
Neutron: 0
3
Q
mass/kg for proton, electron and neutron
A
proton: 1.673 x 10^-27
Neutron: 1.675 x 10^-27
Electron: 0.911 x 10^-30
4
Q
charge for proton, electron and neutron?
A
proton: +1.602 x 10^-19
Electron: -1.602 x 10^-19
Neutron: 0
5
Q
Democritus?
A
- Democritus (460-370 BC)
Theorized that all matter is composed
of small indivisible particles called atomos (“not to cut”)
Ideas rejected by Greek thinkers of that time favoured four elements of earth, fire, water and air
The concept of the atom re-emerged in the 1600’s
6
Q
Robert Boyle?
A
- Robert Boyle (1661)
Some substances cannot be made simpler What we now know as elements
7
Q
John dalton?
A
- John Dalton (1803)
Elements composed of indivisible atoms. Atoms of a particular element have the same mass
Atoms cannot be broken down
8
Q
Henri Becquerel
A
- Henri Becquerel (1896)
Discovered radioactivity showed that particles could come from within the atom
Atoms are not indivisible!
9
Q
JJ Thomson
A
- J.J. Thomson (1897)
Discovered the electron and showed it is negatively charged and much lighter than whole atoms
Created a model for the atom negative electrons scattered in a positive atom
10
Q
Ernest Rutherford
A
- Ernest Rutherford (1911)
Most of the mass, and all the positive charge, found in a tiny central nucleus
Positive alpha particles fired at gold foil
Most pass straight through positive nucleus therefore must be tiny (most of atom is empty space)
11
Q
Niels Bohr
A
- Niels Bohr (1913)
Negatively charged electrons orbit the nucleus
Orbit in shells, movement between shells explains how atoms absorb and emit light, beginning of quantum theory
