Atomic structure

Question 1

What is the plum pudding model?

Answer 1

What atoms were considered to be before Rutherford’s experiment. Electrons were negative ‘plums’ embedded in a ball of positive ‘pudding’.

Question 2

What is the mass of a proton?

Answer 2

1

Question 3

What is the mass of a neutron?

Answer 3

1

Question 4

What is the mass of an electron?

Answer 4

0

Question 5

What is the charge of a proton?

Answer 5

+1

Question 6

What is the charge of a neutron?

Answer 6

0

Question 7

What is the charge of an electron?

Answer 7

-1

Question 8

What are the outcomes of Rutherford’s experiment?

Answer 8

Most of the fast, highly charged particles went whizzing through undeflected.
Some of the alpha particles were reflected back through at large angles.
A small number of the alpha particles (1/8000) were deflected back.

Question 9

What were the conclusions of Rutherford’s experiment?

Answer 9

1) Most of the atom is empty space.
2) There is a positive charge somewhere in the atom.
3) the nucleus carries most of the atom’s mass, also the concentrated mass is tiny.

Question 10

What are isotopes?

Answer 10

Isotopes are atoms with the same number of protons but a different number of neutrons.

Question 11

What is the atomic number?

Answer 11

Number of protons or electrons.

Question 12

What is the mass number?

Answer 12

Number of protons plus number of neutrons. (Mass number is the bigger number)

Question 13

What are non stable isotopes?

Answer 13

They tend to be radioactive, which means they decay into other elements and give out radiation.

Question 14

How do unstable isotopes become stable?

Answer 14

By releasing different types of particles, this is radioactive decay.

Question 15

What are elements that undergo radioactive decay?

Answer 15

Radioisotopes/ radionuclides.

Question 16

What do radioactive substances do?

Answer 16

Give out radiation from the nuclei of their atoms.

Question 17

What sort of process is radioactivity?

Answer 17

Random.

Question 18

What are the three types of radiation?

Answer 18

Alpha, Beta and Gamma

There is a 4th type of decay that can emit a neutron

Question 19

Describe alpha.

Answer 19

Has a helium nucleus.

Question 20

Describe Beta.

Answer 20

A high speed electron.

Question 21

Describe Gamma.

Answer 21

A wave of electromagnetic radiation.

Question 22

What is the electric charge of alpha?

Answer 22

+2

Question 23

What is the electric charge of Beta?

Answer 23

-1

Question 24

What is the electric charge of Gamma?

Answer 24

0

Question 25

What is the relative atom mass of alpha?

Answer 25

4

Question 26

What is the relative atomic mass of Beta?

Answer 26

1/2000

Question 27

What is the relative atomic mass of Gamma?

Answer 27

0

Question 28

What is the penetration power of alpha?

Answer 28

The least | Cannot pass through skin.

Question 29

What is the penetration power of Beta?

Answer 29

Medium | Cannot pass through aluminium.

Question 30

What is the penetration power of Gamma?

Answer 30

The most | Can pass through lead.

Question 31

What ionising effect does alpha have?

Answer 31

The most.

Question 32

What ionising effect does Beta have?

Answer 32

Medium

Question 33

What ionising effect does Gamma have?

Answer 33

The least.

Question 34

What does the effects of a magnetic/ electric field on Alpha?

Answer 34

It’s deflected a little.

Question 35

What does the effects of a magnetic/ electric field on Beta?

Answer 35

It’s deflected a lot.

Question 36

What does the effects of a magnetic/ electric field on Gamma?

Answer 36

Nothing.

Question 37

What is the general formulae of alpha?

Answer 37

Reduces atomic number by 2 and mass number by 4.

Question 38

What is the general formulae for Beta?

Answer 38

Increases atomic number by 1.

Question 39

What is the general formulae for Gamma?

Answer 39

There is no change.

Question 40

What is alpha used for?

Answer 40

Smoke alarms. | Alpha ionises the air and causes charged particles to flow, if smoke is present this stops and the alarm goes off.

Question 41

What is Beta used for?

Answer 41

Thickness control | E.g if aluminium foil is too thick less Beta gets through but if it’s too thin more Beta gets through.

Question 42

What is Gamma used for?

Answer 42

Radiotherapy Gamma rays are aimed at a tumour, a high dose kills cancer cells. Sterilisation of food and surgical equipment. Will kill all microbes on food. Does not use high temperature, so things like fruit and plastic can be sterilised without being damaged. Does not leave food radioactive.

Question 43

What is half life?

Answer 43

Time for half the unstable nuclei to decay.

Question 44

What is a short half life?

Answer 44

When the activity falls quickly because lots of the nuclei decay quickly.

Question 45

What is a long half life?

Answer 45

He activity falls more slowly because most of the nuclei don’t decay for a long time.

Question 46

How is cancer caused by radiation?

Answer 46

Alpha, beta and Gamma can enter cells which collide with molecules. These collisions cause ionisation, which damages or destroys the molecules. Small doses can lead to mutant cells which divide uncontrollably.

Question 47

What safety precautions should you take when handling radioactive substances?

Answer 47

Never allow skin contact with a source, always use tongs. Hold the source am arms length away from you so that the amount of radiation that hits you decreases. Always store the sample in a lead box- lead absorbs radiation.

Question 48

What is radiation?

Answer 48

Energy transferred by particles or waves emitted from the nucleus.

Question 49

What is a nucleon?

Answer 49

Collective names for protons and neutrons.

Question 50

What is irradiation?

Answer 50

Exposure to radiation.

Question 51

What is a bequerel (Bq)?

Answer 51

The unit of activity.

Question 52

What is activity?

Answer 52

Number of decay per second.

Question 53

What is nuclear fission?

Answer 53

When a heavy nucleus splits in two smaller nuclei which releases energy. The isotopes most used in nuclear reactors are uranium (235) and plutonium (239).

Question 54

What 3 things are produced in a single fission reaction?

Answer 54

- Energy in the form of heat - Two or three smaller nuclei - 3/a few moving single neutrons

Question 55

How does a chain reaction work?

Answer 55

A neutron hits a nucleus. The nucleus splits into smaller nuclei and some more neutrons. These hit more nuclei.

Question 56

What is nuclear fusion?

Answer 56

When two smaller atoms join together to form a bigger one.

Question 57

What does nuclear fusion generate?

Answer 57

Heat energy

Question 58

How does nuclear fusion work with a gas?

Answer 58

If you super heat a gas, the atom has so much energy that its electrons become excited and shed off. This ionises the particle allowing them to conduct electricity. As the electrons return to their low energy state, the give off EM radiation.

Question 59

How do you start a fusion reaction?

Answer 59

The fuel must be heated at a temperature of about 15 million degrees. This makes plasma, a gas which the electrons have been stripped from the nuclei.