The Atom

Question 1

Diffusion is

Answer 1

The spreading of particles from a region of high concentration to a region of low concentration

Question 2

State John Daltons Atomic Theory

Answer 2

1. Matter is made of small particles
2. He called these particles atoms.
3. Atoms are indivisible and cannot be broken into smaller parts

Question 3

What was Williams Crookes contribution to the discovery of the electron

Answer 3

1. Wanted to prove there was something coming out of the negative end of battery.
2. Used a vacuum tube
3. Found radiation coming from cathode(negative)
4. Placed Maltese cross inside tube and noticed a shadow forming
5. Knew that the Maltese cross had to be blocking something
6. Called these invisible rays cathode rays

Question 4

Crookes Second experiment?

Answer 4

1. Set up cathode rays to hit a paddle wheel using a battery
2. When the battery was turned on the paddle wheels moved
3. Something strong enough had to be pushing it

Question 5

Crookes Conclusion

Answer 5

Cathode rays travel in straight lines

They cause glass to glow/fluorescent

They have enough energy to move a paddle wheel

Question 6

JJ Thompson contribution

Answer 6

1. Wanted to prove if these cathode rays were positive or negative
2. Passed narrow beam of cathode rays between charged plates.
3. Using electromagnet he discovered that streams of electrons were deflected towards positive plate.
4. Calculated mass/ charge ratio

Question 7

Who came up with the name Electron

Answer 7

George Stoney

Question 8

Cathode Rays are

Answer 8

Streams of negatively charged particles called electrons

Question 9

Robert Milikan contribution

Answer 9

1. Wanted to find the exact size of a charge of electron and calculate its mass
2. Ionised air molecules and sprayed oil into machine
3. The oil picked up electrons lost from air
4. Had two charged plates
5. Charged plates suspended the oil in mid air and the charge of the oil drop was calculated

Question 10

JJ Thomson Plum Pudding

Answer 10

Simple structure of an atom describing it as a sphere with positive surface and negative charges placed randomly around the surface to cancel out the charge

Question 11

Ernest Rutherford discovery of Nucleus

Answer 11

1. Bombarded thin leaf of gold foil with positively charged alpha particles.
2. He discovered:

Many went straight through

Some were deflected

Some were reflected back along their own path

Small core in centre called nucleus

Question 12

Ernest Rutherford Discovery of Proton

Answer 12

Discovered positive charged particles were given off when oxygen and nitrogen were bombarded with alpha particles

The nuclei of the atoms were breaking up and protons were given out

Question 13

James Chadwick discovery of neutron

Answer 13

Bombarded beryllium with alpha particles and discovered that particles with no charge were released from the nucleus.
They had the same mass as proton

Question 14

Subatomic particles

Answer 14

Proton, Neuton and Electron

Proton is located in nucleus with a charge of 1 and mass of 1 a.m.u

Electron is located outside nucleus with a charge of -1 and mass of 1/1838 a.m.u

Neuton is located in nucleus with a charge of 0 and mass of 1 a.m.u

Question 15

an electron is

Answer 15

A subatomic particle