Atomic Structure and Radioactivity

Question 1

JJ thompson’s plum pudding model

Answer 1

Introduced the idea of subatomic particles - the atom is a uniform, positively charged sphere containing electrons in the sphere that were negatively charged, balacing out the energy

Question 2

Rutherfords Atomic model

Answer 2

a small, positively-charged nucleus surrounded by empty space and then a layer of electrons to form the outside of the atom

Question 3

Rutherford - Bohr model

Answer 3

electrons orbit the nucleus in shells (energy levels)

Question 4

Rutherford’s Gold Foil Experiment

Answer 4

Alpha-particles were directed at a thin sheet of gold foil; most passed through the foil, but a few were deflected - this led to the discovery of the atomic nucleus

Question 5

what is an alpha particle

Answer 5

A helium nucleus

Question 6

radius of an atom

Answer 6

1 x 10^-10m

Question 7

basic structure of an atom

Answer 7

positively charged nucleus composed of both protons and neutrons surrounded by shells with electrons

Question 8

where is the majority of the mass of an atom concentrated

Answer 8

the nucleus

Question 9

How are electrons arranged

Answer 9

at different energy levels in different distances from the nucleus.

Question 10

how can electrons move closer to the nucleus

Answer 10

emission of electromagnetic radiation, goes to a lower energy level

Question 11

how can electrons move further away from the nucleus

Answer 11

absorption of electromagnetic radition, moves to a higher energy level.

Question 12

Mass number

Answer 12

protons + neutrons

Question 13

atomic number (proton number)

Answer 13

number of protons in atom. atoms of same element have same number of protons

Question 14

Element

Answer 14

substance made of one type of atom

Question 15

Isotope

Answer 15

atoms of same element with different amount of neutrons

Question 16

proton relative mass

Answer 16

1

Question 17

neutron relative mass

Answer 17

1

Question 18

electron relative mass

Answer 18

approximately 1/2000

Question 19

Nucleons

Answer 19

collective term for protons and neutrons. particles found in the nucleus of atoms.

Question 20

proton relative charge

Answer 20

+1

Question 21

neutron relative charge

Answer 21

0

Question 22

electron relative charge

Answer 22

-1

Question 23

how are atoms represented

Answer 23

Atomic symbol in the middle.
Mass number (A) in the top left
Atomic number (X) in the bottom left

Question 24

how do atoms turn into positive ions

Answer 24

lose electron(s)

Question 25

what were atoms thought of before the discovery of the electrons

Answer 25

tiny sphere that could not be divided

Question 26

what did James Chadwick do

Answer 26

discovered the existence of neutrons within the nucleus

Question 27

photon

Answer 27

Photons are particles that travel through the wide spaces between atoms

Question 28

what does a photon represent

Answer 28

a particle representing a quantum of light or other electromagnetic radiation. A photon carries energy proportional to the radiation frequency

Question 29

Energy associated with a single photon equation

Answer 29

Energy (E) = Planck's constant (h) x frequency of radiation (f) ## Footnote E = hf

Question 30

What substances are said to be radioactive

Answer 30

substances that give out radiation from unstable nuclei all the time

Question 31

Radioactive decay

Answer 31

Some atomic nuclei are unstable.Radioactive decay happens when the nucleus gives out radiation as it changes to be more stable.

Question 32

Activity is:

Answer 32

rate at which a source of unstable nuclei decays.

Question 33

What is activity measured in

Answer 33

becquerel (Bq)

Question 34

Count rate is

Answer 34

the number of decays recorded each second by a detector

Question 35

example of a count rate detector

Answer 35

Geiger-Muller tube

Question 36

3 types of nuclear radiation

Answer 36

alpha particle beta particle gamma ray

Question 37

alpha particle

Answer 37

consists of 2 neutrons and 2 protons, same as a helium nucleus ## Footnote symbol:α

Question 38

beta particle

Answer 38

high speed electron ejected from nucleus as neutron turns into proton ## Footnote symbol:β

Question 39

gamma ray

Answer 39

electromagnetic radiation from the nucleus ## Footnote symbol:γ

Question 40

properties of alpha particles

Answer 40

relative mass - 4 charge is + helium nucleus high ionisation low penetrating power stopped by paper or skin short range in air

Question 41

properties of beta particles

Answer 41

relative mass - 1/2000 charge is - medium ionising power medium penetrating power stopped by aluminium medium range in air

Question 42

properties of gamma rays

Answer 42

relative mass - 0 no charge type of em radiation low ionisation high penetrating power stopped by lead or concrete very long range in air

Question 43

whats used to represent radioactive decay

Answer 43

Nuclear equations

Question 44

Radioactive contamination

Answer 44

unwanted presence of materials containing radioactive atoms.

Question 45

hazard of radioactive contamination

Answer 45

decay of contaminating atoms would emit radiation

Question 46

Irradiation

Answer 46

exposing an object to nuclear radiation. Irradiated object does not become radiaoactive.

Question 47

background radiation is not around us all the time. True or false

Answer 47

False, it is

Question 48

natural sources of background radiation

Answer 48

rocks and cosmic rays from space

Question 49

man made sources of background radiation

Answer 49

fallout from nuclear weapons testing and nuclear accidents

Question 50

level of background radiation is affected by:

Answer 50

Occupation and or location