The basic structure of an atom is a small central __________ composed of __________ and __________ surrounded by __________.
The atoms of an element always have the same number of __________, but have a different number of __________ for each isotope.
Some substances 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.