Topic 6: radioactivity

Question 1

describe an atom

Answer 1

a positively charged nucleus, consisting
of protons and neutrons, surrounded by negatively charged
electrons, with the nuclear radius much smaller than that of
the atom and with almost all of the mass in the nucleus

Question 2

what is the typical diameter of an atom

Answer 2

0.1 nm
or
1 x 10^-10

Question 3

what is an isotope

Answer 3

isotopes are the same element with the same mass number but different atomic mass (different number of neutrons)

Question 4

what is the relative mass and relative charge of a electron

Answer 4

mass: 0.0005
charge: -1

Question 5

what is the relative mass and relative charge of a proton

Answer 5

mass: 1
charge: +1

Question 6

what is the relative mass and relative charge of a neutron

Answer 6

mass: 1
charge: 0

Question 7

what happens to an atom when it loses an electron

Answer 7

it gains a positive charge due to the lose of -1 charged particles

Question 8

what are emitted from unstable nuclei

Answer 8

alpha particles
β– (beta minus)
β+ (positron)
gamma rays
and neutron radiation

Question 9

what is background radiation

Answer 9

the radiation that is always present in the environment

Question 10

what are the main sources of background radiation

Answer 10

radon gas
cosmic rays from space
medical
food and drink
ground and building

Question 11

how do photographic film detect radiation

Answer 11

When exposed to ionising radiation, photographic film will turn from being transparent to dark and non-transparent

Question 12

an alpha particle is equivalent to a ______ nucleus

Answer 12

helium