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Science

Chemical calculations - both Tiers

Isotopes

Isotopes are atoms of an element with the normal number of protons and electrons, but different numbers of neutrons. Isotopes have the same atomic number, but different mass numbers.

The different isotopes of an element have identical chemical properties. However, some isotopes are radioactiveradioactive: A substance that emits radiation is said to be radioactive..

Isotopes of hydrogen

Most hydrogen atoms consist of just one protonproton: A proton is a small particle with a positive charge found in the nucleus of the atom. and one electron [electron: An electron is a very small negatively-charged particle found in an atom in the space surrounding the nucleus. ], but some also have one or two neutronsneutrons: Uncharged sub-atomic particles, with a mass of 1 relative to a proton..

Isotopes of hydrogen

Isotopeprotonselectronsneutrons
H 1,1111 - 1 = 0
H 2,1112 - 1 = 1
H 3,1113 - 1 = 2

Isotopes of chlorine

Chlorine atoms contain 17 protons and 17 electrons. About 75 per cent of chlorine atoms have 18 neutrons, while about 25 per cent have 20 neutrons.

Isotopes of chlorine

Isotopeprotonselectronsneutrons
Cl 35, 17171735 - 17 = 18
Cl 37,17171737 - 17 = 20

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