6.2

Question 1

Isotopes

Answer 1

atoms of the same element that differ in the number of neutrons in the nucleus

Question 2

Stable

Answer 2

describes a nucleus that does not change spontaneously. The protons and neutrons in the nucleus are held together strongly.

Question 3

Unstable

Answer 3

describes an atom in which the neutrons and protons in the nucleus are not held together strongly

Question 4

Radioisotopes

Answer 4

a radioactive form of an isotope

Question 5

Nuclear radiation

Answer 5

radiation from the nucleus of an atom, consisting of alpha or beta particles, or gamma rays

Question 6

Alpha particles

Answer 6

positively charged nuclei of helium atoms, consisting of two protons and two neutrons

Question 7

Beta particles

Answer 7

charged particles (positive or negative) with the same size and mass as electrons

Question 8

Gamma rays

Answer 8

high-energy electromagnetic radiation produced during nuclear reactions. They have no mass and travel at the speed of light

Question 9

Half-life

Answer 9

time taken for half the radioactive atoms in a sample to decay—that is, change into atoms of a different element

Question 10

Cosmic radiation

Answer 10

naturally occurring background radiation from outer space