P4/Atomic Structure

Question 1

what is the radius of an atom?

Answer 1

1x10-10 m

Question 2

which two particles make up the nucleus of an atom?

Answer 2

protons and neutrons

Question 3

where, in an atom, are the electrons found?

Answer 3

orbiting the nucleus

Question 4

the radius of the nucleus is what fraction of the radius of the atom?

Answer 4

1/10,000

Question 5

what do we call the different distances that the electrons can be from the nucleus?

Answer 5

energy nucleus

Question 6

how can an electron move to a higher energy level?

Answer 6

when the atom absorbs electromagnetic radiation

Question 7

which number tells us the number of protons?

Answer 7

the atomic number

Question 8

how can you work out the number of neutrons in an atom?

Answer 8

mass number-atomic number

Question 9

what do we call atoms of the same element that have different numbers of neutrons?

Answer 9

isotopes

Question 10

what do atoms turn into if they lose one or more of their outer electrons?

Answer 10

positive ions

Question 11

before the discovery of the electron, atoms were thought to be what?

Answer 11

tiny spheres that could not be divided into anything smaller

Question 12

the discovery of the electron led to which model of the atom?

Answer 12

the plum pudding model

Question 13

the plum pudding model suggested that the atom is a ball of positive charge with negative electrons located where?

Answer 13

embedded everywhere in it

Question 14

the results from the alpha particle scattering experiment led to the conclusion that the mass of an atom was concentrated at the centre (nucleus) and that the nucleus was what?

Answer 14

positively charged

Question 15

the nuclear model replaced what?

Answer 15

the plum pudding model

Question 16

Niels Bohr adapted the nuclear model by suggesting that electrons orbit the nucleus in what?

Answer 16

shells

Question 17

later experiments led to the idea of which particle?

Answer 17

the positively charged proton

Question 18

the experimental work of James Chadwick provided the evidence to show the existence of which particles within the nucleus?

Answer 18

neutrons

Question 19

what do we call the process when an unstable nucleus gives out radiation to become a more stable nucleus?

Answer 19

radioactive decay

Question 20

what do we call the rate at which a source of unstable nuclei decay?

Answer 20

activity

Question 21

what is the unit for activity?

Answer 21

becquerel (Bq)

Question 22

what do we call the number of decay that are detected each second?

Answer 22

count-rate

Question 23

what is an alpha particle made of?

Answer 23

2 protons and 2 neutrons

Question 24

what is a beta particle?

Answer 24

a high speed electron

Question 25

what happens in the nucleus to make a beta particle?

Answer 25

a neutron turns into a proton

Question 26

what is gamma radiation?

Answer 26

electromagnetic radiation from the nucleus

Question 27

what can stop alpha particles?

Answer 27

a sheet of paper, a few cm of air or skin

Question 28

what would you need to stop gamma radiation?

Answer 28

a few cm of lead or a few metres of concrete

Question 29

which type of radiation is the most ionising?

Answer 29

alpha

Question 30

which type of radiation is the least ionising?

Answer 30

gamma

Question 31

what name is given to the amount of time it takes for half of a radioactive sample to decay?

Answer 31

half-life

Question 32

what do we call the presence of unwanted radioactive atoms on or in other materials?

Answer 32

contamination

Question 33

what do we call the exposure of objects to radioactivity?

Answer 33

irradiation

Question 34

what do we call the radiation that is around us all the time?

Answer 34

background radiation

Question 35

what units do we measure radiation dose in?

Answer 35

seiverts (Sv) or millisieverts (mSv)

Question 36

give two ways in which radioactivity is used in medicine?

Answer 36

exploration of internal organs | control and destruction of cancerous tissue

Question 37

what name is given to the splitting of a large nucleus in to two smaller nuclei?

Answer 37

nuclear fission

Question 38

what particle must be absorbed by a nuclei to undergo fission?

Answer 38

neutron

Question 39

which particles are produced during nuclear fission?

Answer 39

2 or 3 more neutrons

Question 40

what else is released in nuclear fission?

Answer 40

energy

Question 41

what is the danger of the extra neutrons?

Answer 41

a chain reaction

Question 42

what is the name given to the joining together of small nuclei to make larger ones?

Answer 42

nuclear fusion

Question 43

during nuclear fusion mass is converted into what?

Answer 43

energy