Topic 3: Atomic structure

Question 1

what are the masses and charges of protons, neutrons and electrons?

Answer 1

protons: mass: 1, charge: 1+
neutrons: mass: 1, charge: 0
electrons: mass: 2/1000, charge: -1

Question 2

what was JJ Thomsons discovery on the atom?

Answer 2

plum pudding model - ball of positive charge with electrons embedded into it

Question 3

what was Dalton’s discovery on the history of the atom?

Answer 3

tiny spheres

Question 4

what was Rutherfords discovery on the atom?

Answer 4

alpha particle experiment
- some alpha particles went straight through - there’s empty space
- some deflected - centre is positive
- some bounced back - centre is dense

discovered the proton

Question 5

what was Bohr discovery on the atom?

Answer 5

discovered electrons were found on shells (not a sea of electrons)

Question 6

what was Chadwick discovery on the atom?

Answer 6

discovered neutrons

Question 7

describe what alpha radiation is, it’s penetration power, the ionisation power and what it’s used for

Answer 7

• alpha is 2 neutrons and 2 protons, nucleus ejects helium nuclei (has a mass of 4 and a charge of +2)
• it’s low penetrating (can be stopped by air, skin, paper)
• high ionisation
• used for smoke alarms

Question 8

describe what beta radiation is, it’s penetration power, the ionisation power and what it’s used for

Answer 8

• beta is fast moving electron (mass nearly 0, charge -1), neutron turns into a proton and electron is ejected from the nucleus
• moderately penetrating (stopped by thin sheet of aluminium)
• moderately ionising
• used for paper mills/ controlling the thickness of paper

Question 9

describe what gamma radiation is, it’s penetration power, the ionisation power and what it’s used for

Answer 9

• gamma is EM waves, high frequency/ short wavelength (mass is 0 and charge is 0)
• it’s high penetrating (can penetrate through the skin)
• low ionising
• sterilising surgical equipment, gamma knife - kills cancerous cells, used to detect leaks in pipes

Question 10

what is fission?

Answer 10

breaking large nuclei into smaller nuclei

Question 11

where does fission occur?

Answer 11

nuclear power stations

Question 12

what is the process of fusion

Answer 12

the joining of light nuclei (hydrogen) to form a heavier nucleus
produces large amounts of energy
no nuclear waste
has not been done earth - don’t get high enough temperature/ pressure

Question 13

what is half life?

Answer 13

the time it takes for half of the nuclei to decay and become stable

Question 14

what is needed for the use of alpha/ beta and gamma?

Answer 14

• half life:
  body - short half life (relatively short)
• type of radiation emitted:
• ionisation power
• penetration