P6.1

Question 1

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

Answer 1

the protons and neutrons are found in the nucleus
the electrons are found in discrete energy levels around the nucleus

Question 2

what type of charge does the nucleus of an atom have? why?

Answer 2

positive
nucleus contains protons and neutrons, protons have positive charge and neutrons have no charge

Question 3

give two ways that an atom’s electron arrangement can be changed

Answer 3

absorbing electromagnetic radiation
emitting electromagnetic radiation

Question 4

explain how an atom’s electron arrangement changes when it absorbs EM radiation

Answer 4

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

Question 5

explain how an atom’s electron arrangement changes when it emits EM radiation

Answer 5

electrons move closer to the nucleus
they move to a lower energy level

Question 6

how does the ratio of electrons to protons in an atom result in the atom having no overall charge?

Answer 6

the number of protons is equal to the number of electrons
protons and electrons have equal and opposite charges, so charge cancels

Question 7

what do all forms of the same element have in common

Answer 7

number of protons

Question 8

what is the name given to the number of protons in an atom?

Answer 8

atomic number

Question 9

what is an atom’s mass number?

Answer 9

the total number of protons and neutrons in the atom

Question 10

what is an isotope of an atom

Answer 10

an atom of an element that has a different number of neutrons, but the same number of protons

Question 11

how do atoms turn into positive ions

Answer 11

losing one or more of their outer electrons.

Question 12

why do unstable nuclei give out radiation?

Answer 12

unstable nuclei undergo decay to become more stable.
as they release radiation their stability increases

Question 13

what is the name of the process in which an unstable nucleus gives out radiation to become more stable?

Answer 13

radioactive decay

Question 14

state 4 types of nuclear radiation

Answer 14

alpha particles
beta particles
gamma rays
neutrons

Question 15

what are the constituents of an alpha particle?

Answer 15

two protons and two neutrons
its the same as a helium nucleus

Question 16

give the equation for an alpha particle

Answer 16

α (4 top number 2 bottom number)

Question 17

what is the range of an alpha particle through air?

Answer 17

a few centimetres ( normally in the range of 2 -10 cm)

Question 18

what will stop beta radiation from passing through a point

Answer 18

a thin sheet of aluminium
several metres of air

Question 19

give the equation for a beta particle

Answer 19

β ( 0 top number, -1 bottom)

Question 20

what will stop gamma radiation from passing through a point?

Answer 20

several centimetres of lead
a few metres of concrete

Question 21

give the equation for γ radiation

Answer 21

γ ( top number 0 bottom number 0)
γ radiation is an EM wave

Question 22

which type of radiation is most ionising?

Answer 22

alpha radiation

Question 23

which type of radiation is least ionising?

Answer 23

gamma radiation

Question 24

state any changes to mass or charge that occur due to the emission of a gamma ray

Answer 24

both mass and charge remain unchanged

Question 25

describe the nature of radioactive decay

Answer 25

random which nuclei decays and when is determined only by chance it is impossible to predict which nuclei will decay and when

Question 26

describe the half-life of a radioactive isotope.

Answer 26

the time it takes for the number of unstable nucelli in a substance to halve the time it takes for the count rate from a sample to fall to half its initial level