The basic structure of an atom is a small central __________ composed of __________ and __________ surrounded by __________.
Atoms of different elements have different numbers of __________. The total number of protons and neutrons (nucleons) in an atom is called its mass (nucleon) number.
The atoms of an element always have the same number of __________, but have a different number of __________ for each isotope.
Some isotopes give out __________ from the __________ of their atoms all the time, whatever is done to them. These substances are said to be __________.
There are three types of radiation emitted by radioactive sources:
Alpha radiation consists of __________ nuclei, particles made up of two protons and two neutrons.
Beta radiation consists of high-energy (fast moving) __________ emitted from the nuclei of atoms. For each electron emitted, a __________ in the nucleus becomes a __________.
Gamma radiation is very __________ wavelength electromagnetic radiation. They are similar to x-rays, but come from energy released from an unstable nucleus, while x-rays get their energy from fast moving electrons.