radioactive decay

Question 1

radioactive emission occurs when

Answer 1

An unstable nucleus attempts to become stable by releasing energy (generally in the form of electrons)

Question 2

Four types of emission

Answer 2

alpha, beta, gamma, positrons

Question 3

Alpha

Answer 3

-A helium nucleus (two protons and two neutrons)
-These eject from the nucleus at high speeds
(4/2 He2+)
- positive, heavy, slow moving (weakly attracted to negative plates of an electric field)

Question 4

Beta

Answer 4

electrons that are ejected from the nucleus at high speeds
0/-1 e
-light and fast moving (strongly attracted to positive plate of an electric field)

Question 5

positrons

Answer 5

anti-electrons ejected from the nucleus at high speeds
-same mass as electrons but opposite charge (positive)
-collision between positron and electrons cause gamma radiation

Question 6

Gamma

Answer 6

High energy electromagnetic radiation
emitted when:
1) heavy nucleus rearranges to be more stables
2) electron collides with a proton heavy nucleus combining to form a neutron (electron capture)
-unaffected by electric field

Question 7

what stops alpha

Answer 7

-large and slow
-can be stopped by single sheet of paper or skin

Question 8

what stops beta

Answer 8

-fast and light
-stopped by thin layers of metal (e.g. aluminium)

Question 9

ionising properties of alpha

Answer 9

-heavy and slow
-highly ionising
-removes electrons from atoms due to their positive charge

Question 9

what stops gamma

Answer 9

-high energy, short wavelength
-most penetrating of the three
-stopped by at least 2cm of metal such as lead

Question 10

ionising properties of beta

Answer 10

-small and fast
-less ionising than alpha
-collide with electrons in atoms and knock out the electrons (ionising the atom)

Question 11

ionising properties of gamma

Answer 11

-electromagnetic wave (high energy,, short wavelength)
-only ionises if the atom absorbs the energy of the radiation
-unlikely due to short wavelength

Question 12

nuclear equations of gamma

Answer 12

Gamma doesn’t affect the object emitting it as it is energy not a particle

Question 13

nuclear equations of alpha

Answer 13

B= C + (helium nucleus)
B is the original element
C is the new element that has an atomic mass that is 2 lower and a relative mass that is 4 lower
the helium nucleus is the alpha radiation

Question 14

nuclear equations of beta

Answer 14

B= C + 0/-1 e
B gains 1 in atomic number but the mass number remains the same as a neutron becomes a proton

Question 15

nuclear equations of positrons

Answer 15

B= C + 0/1 e
B loses 1 in atomic number as a proton becomes a neutron. Mass is unchanged

Question 16

nuclear equations of electron capture

Answer 16

C+ 0/-1 e = B
atomic number decreases as proton becomes a neutron

Question 17

beta vs positron

Answer 17

when losing a negative electron the atomic number goes up by one

when losing a positive it goes down by one