P4 ATOMIC STRUCTURE

Question 1

3 subatomic consistuents of an atom?

Answer 1

proton
neutron
electron

Question 2

describe the arrangement of protons , neutrons and electrons in an atom

Answer 2

protons and neutrons = nucleus
electrons = energy levels around the nucleus

Question 3

what type of charge does nucleus have?

Answer 3

positive because nucleus contains protons which have a positive charge and neutrons have no charge

Question 4

2 ways that an atoms ‘s electron arrangement can be changed

Answer 4

absorbing electromagnetic radiation
emitting electromagnetic radiation

Question 5

explain how an atoms’s electrons arrangement changes when its emits EM radiation?

Answer 5

The electron moves closer to the nucleus.
they move to a lower energy level

Question 6

explain how an atoms electrons arrangement changes when its absorbs EM radiation?

Answer 6

electrons move further away from the nucleus
move to a higher energy level

Question 7

what do all forms of the same element have in common?

Answer 7

same number of protons

Question 8

how do atoms turn into positive ions?

Answer 8

lose one or more electrons on the outer shell

electrons are negatively charged so the resultant charge of the atom is positive

Question 9

what may lead to a scientific model being changed or replaced?

Answer 9

discovery of new experimental evidence which doesn’t agree with the existing theory

Question 10

prior to the discovery of the electron , what was believed about the atom?

Answer 10

atom was believed to be indivisible

Question 11

which experiment led to to the plum pudding model being discarded?

Answer 11

rutherford’s alpha scattering experiment

Question 12

what is the name given to the currently accepted model of the atoms?

Answer 12

bohr nucleus model

Question 13

state the conclusions of the alpha scattering experiment?

Answer 13

most of the mass was in the nucleus
nucleus has a positive charge.

Question 14

what reinforces a scientific theory?

Answer 14

when experimental results agree with the hypothesised theoretical calculations and theories

Question 15

why do unstable nuclei give out radiation?

Answer 15

become more stable
as they release more radiation their stability increases

Question 16

what is radioactive decay?

Answer 16

when an unstable nucleus gives out radiation as it changes to become more stable.

Question 17

activity ?

Answer 17

the rate at which an unstable nucleus decays

Question 18

unit for activity?

Answer 18

becquerel (bq)

Question 19

count rate?

Answer 19

number of decays recorded each sec by a detector

Question 20

an example of a detector that may be used to measure count rate?

Answer 20

geiger-muller tube

Question 21

4 types of nuclear radiation?

Answer 21

alpha , beta , gamma and neutrons

Question 22

structure of alpha particles?

Answer 22

2 neutrons
2 protons
same as helium nucleus.

Question 23

structure of beta particles?

Answer 23

high speed electrons that are released from the nucleus

Question 24

structure of gamma rays?

Answer 24

electromagnetic radiation that is released from the nucleus

Question 25

put alpha beta and gamma radiation in order from most to least penetrating?

Answer 25

gamma , beta , alpha

Question 26

put alpha , beta and gamma radiation in order from longest range in air to shortest range in air

Answer 26

gamma beta , alpha

Question 27

put alpha , beta , gamma radiation from most to least ionising?

Answer 27

alpha , beta , gamma

Question 28

state the materials that can stop alpha particles

Answer 28

skin , paper , a few centimetres of air

Question 29

state the materials that can stop beta particles

Answer 29

aluminium foil

Question 30

state the materials that can stop gamma rays

Answer 30

thick lead or concrete

Question 31

give the symbol that represents alpha particles in nuclear decay equations

Answer 31

4
He
2

Question 32

give the symbol that represents beta particles in nuclear decay equations

Answer 32

0
e
-1

Question 33

what happens to the atomic number and mass number of nucleus when an alpha particle is released?

Answer 33

atomic number decreases by 2

the mass number decreases by 4

Question 34

what happens to the charge of a nucleus when an alpha particle is released

Answer 34

charge decreases by 2

Question 35

what happens to the atomic number and mass number of a nucleus when a beta particle is released

Answer 35

atomic number increases by 1
mass number stays the same

Question 36

what happens in the nucleus when a beta particle is released?

Answer 36

a neutron turns into protons and releases beta particle

Question 37

what happens to the charge of a nucleus when a beta particle is released?

Answer 37

increases by 1

Question 38

what happens when the mass and charge of a nucleus when a gamma ray is emitted?

Answer 38

nothing it stays the same

Question 39

state the word used to describe radioactive decay

Answer 39

random

Question 40

define half life

Answer 40

the time taken for the number of nuclei , or count rate or activity of a sample to halve

Question 41

describe 2 things we cannot know about radioactive decay?

Answer 41

do not know which nucleus will be next to decay.
do not know how long it will take for a specific nucleus to decay

Question 42

radio contamination?

Answer 42

unwanted presence of materials containing radioactive atoms in other materials

Question 43

irradation?

Answer 43

exposing an object to nuclear radiation. the object does not become radioactive

Question 44

why is it important for the results of studies on the effects of radiation to be published and shared with other scientist.

Answer 44

to allow findings to be checked independently
this is known as peer review

Question 45

state 5 precautions to take when using radioactive sources

Answer 45

keep sources in a lead lined box
wear face masks to prevent breathing in materials
wear gloves to prevent contamination of the skin
limit the time spent with radioactive sources
use tongs or robotic arms to handle sources to keep them far away from the body.