Atomic Structure

Question 1

Who came up with the Plum Pudding model? And what was it like?

Answer 1

J J Thomson - He suggested a sphere of positive charge with tiny negative electrodes in it

Question 2

Why didn’t the plum pudding model last?

Answer 2

In 1909 scientist Rutherford tried firing a beam of alpha particles at thin gold foil. They expected them to pass straight though or be slightly deflected but instead they came straight back. This was because the nucleus had a positive charge. This meant the plum pudding was wrong.

Question 3

What was created after the plum pudding model?

Answer 3

The nuclear model was created by Bohr and showed electrons orbiting the nucleus.

Question 4

In atoms how many protons and electrons are there?

Answer 4

There are an equal number of protons and electrons - These are the top number atomic number. The bottom number is the mass number.

Question 5

What is an isotope?

Answer 5

An isotope is the same element but with a different number of neutrons.

Question 6

Which elements have isotopes?

Answer 6

All elements have isotopes but only 1 or 2 stable ones .

Question 7

What happens to unstable isotopes?

Answer 7

Most unstable isotopes decay into other elements - This is called radioactive decay.

Question 8

Alpha particles features:

Answer 8

They are helium nuclei
They have 2 protons and 2 neutrons
They don’t penetrate far because they are strongly ionising

Question 9

Beta particles features:

Answer 9

They are high speed electrons

They are moderately ionising so penetrate quite far

Question 10

Gamma Rays Features:

Answer 10

They are EM waves with a short wavelength
They penetrate far into materials and through the air as they are weakly ionising.
They can be absorbed by thick sheets of concrete

Question 11

What charge do Protons , neutrons and electrons have?

Answer 11

Protons: +1 or positive
Neutrons: 0 or neutral
Electrons: -1 or negative

Question 12

Radioactive decay is completely random.

So how do you calculate how long it takes to decay

Answer 12

You measure they decay in half life

Question 13

What is decay measured in?

Answer 13

IT is measured in Bq which is 1 decay per second

Question 14

What is the half life?

Answer 14

The half life is the time it takes for the number of radioactive nuclei in an isotope to halve

Question 15

What does irradiated mean?

Answer 15

It means exposed to background radiation

Question 16

What is background radiation?

Answer 16

Daily radiation let off by everything rocks,house, the ground but in too small an amount to be harmful.

Question 17

If something is irradiated will it become radioactive?

Answer 17

NO 😒

Question 18

What is contamination?

Answer 18

Contamination is radiation going into objects

Question 19

What precautions are taken to stop contamination?

Answer 19

Gloves and tongs as if it gets under the skin and decays it will damage your cells.

Question 20

Outside the body what is the most dangerous? Radiation

Answer 20

Beta and gamma as they can easily pass through the skin and penetrate the organs.

Question 21

Inside the body what is the most dangerous? Radiation

Answer 21

Alpha as it is highly ionising and will do a lot of damage to cells but cant get through the skin.

Question 22

What sort of radiation is used in medical treatment and why is it suitable?

Answer 22

They use gamma radiation as it can penetrate the cells but wont damage the person as it will decay quickly and not be very ionising.

Question 23

What is cancer treated with?

Answer 23

Radiotherapy - Gamma rays carefully projected on cancerous cells to kill them. This can damage other cells as well. );

Question 24

What is nuclear fission?

Answer 24

The splitting of unstable nucleus by firing atoms at it.

Question 25

What is nuclear fusion. NOT FISSION

Answer 25

When two high speed nuclei collide and join to create a larger heavier nucleus. It releases a lot of energy and the temperatures and pressure needed to do it are extreme.