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Radioactivity (At the centre of every atom is a nucleus (The number of…
Radioactivity
At the centre of every atom is a nucleus
The number of protons in the nucleus is called the atomic number, or proton number. The total number of protons and neutrons in the nucleus is called the mass number, or nucleon number.
The electrons are negatively charged and really small. They whizz around the outside of the atom. Their paths take up a lot of space, giving the atom it's overall size (though it's mostly empty space).
The nucleus of an atom contains protons and neutrons. It makes up most of the mass of an atom, but takes virtually no space - it's tiny.
Atoms are neutral, so the number of protons = the number of electrons
Radioactive Decay is a random process
Each nucleus just decays spontaneously in its own time. It's completely unaffected by physical conditions like temperature or by any sort of chemical bonding etc.
When the nucleus does decay it spits out one or more types of radiation - alpha, beta, gamma, or neutrons.
The nuclei of unstable isotopes break down at random. If you have 1000 unstable nuclei, you can't say when any one of the is going to decay, and you can't do anything at all to make a decay happen.
In the process, the nucleus often changes into a new element.
Background radiation is everywhere all the time. It comes from:
Radiation from space (cosmic rays) - mostly from the sun.
Living things - there's a little bit of radioactive material in all living things.
Substances on earth - some radioactivity comes from the air, food, building materials, soil, rocks...
Radiation due to human activity - e.g. fallout from nuclear explosions, or nuclear waste.
Isotopes are atoms with different numbers of neutrons
E.g. there are 2 common isotopes of carbon. Carbon-14 has two more neutrons than Carbon-12
Usually each element only has one or two stable isotopes - like Carbon-12. The other isotopes tend to be radioactive - the nucleus is unstable, so it decays (breaks down) and emits radiation. Carbon-14 is an unstable isotope of carbon.
Many elements have a few different isotopes. Isotopes are atoms with the same number of protons (and electrons) but a different number of neutrons. They have the same atomic number but different mass numbers.