Properties of Radiation

When radiation from radioactive materials __________ with neutral atoms or molecules these may become __________ (charged). When radiation ionises molecules in living cells it can cause damage, including __________.

The larger the dose of radiation the greater the risk of cancer. As radiation passes through a material it can be absorbed. The greater the thickness of a material the greater the absorption:

• alpha (α) radiation, easily absorbed by __________ of air or a thin sheet of paper;
• beta (β) radiation, easily passes through air or paper but is mostly absorbed by __________ of metal;
• gamma (γ) radiation, is very penetrating and requires __________ of lead or metres of concrete to absorb most of it.

When sources of radiation are inside the body:

• alpha radiation is the most dangerous because it is so strongly absorbed by cells;
• beta and gamma radiation are less dangerous because cells are less likely to absorb the radiation.

When sources of radiation are outside the body:

• beta and gamma radiation are the most dangerous because they can reach the cells of organs and may be absorbed by them;
• alpha radiation is least dangerous because it is unlikely to reach living cells.