Chapter 2.2 The Discovery of Atomic Structure

Question 1

Cathode Rays

Answer 1

When high voltage was applied to the electrodes inside a glass tube almost empty of air, radiation was produced between the electrodes.

The radiation is called Cathode Rays.

They originated at the negative electrode and travelled to the positive electrode
. was originally described as a stream of negatively charged particles ( electrons)

Question 2

How do we know that cathode rays travel from cathode (-) to anode(+)

Answer 2

Because the fluorescent light of the rays are deflected by a magnet

Question 3

The accepted value for the mass of an electron

Answer 3

9.10938 x10^-28

Question 4

RADIOACTIVITY

Answer 4

The spontaneous emission of radiation

Question 5

Rutherford’s 3 types of radiation

Answer 5

1. alpha ( carries a 2+ charge)
2. beta ( 1-)
3. gamma ( does not consist of particles and does not have a charge)
   alpha and Beta consists of fast moving particles ( beta electrons with a negative charge

Question 6

Rutherford nuclear model of the atom

Answer 6

a model in which most of the mass of each gold atom and all of its positive charge reside in a very dense region he called the nucleus.
.Most of the volume of an atom is empty space in which electrons move around the nucleus.

Question 7

Explain Rutherford’s alpha scattering experiment

Answer 7

Most of the particles passed through the foil unscattered because they did not encounter the minute nucleus of any gold atom ( they passed through mostly empty space.

occasionally an alpha particle would come come close to the positively charge nucleus creating a repulsion reflecting the ray