physics

physics

1. Atoms are very small, they have a radius of around 1 × 10-10 metres.

2. A Becquerel is one decay per second.

3. Some substance are classed as "radioactive" this means that they are unstable and continuously give out radiation at random intervals in a process called "radioactive decay"

4. The term half life is that time taken for the radioactivity of a specified isotope to fall to have half its value

5. The atomic number tells us how many protons and electrons an element has.

6. The atomic mass tells us the total number of protons and neutrons an element has

7. The number of protons and the number of electrons in an atom are always equal

8. Two atoms of the same element with the same number of protons but a different number of neutrons are called isoypes

9. If an atom loses or gains an electron it becomes an ion

10. When atoms of the same element have different numbers of neutrons they are called isotopes.