Isotopes and ions
Isotopes
Atoms of an element with the same number of protons and electrons but different numbers of neutrons. of an A substance made of one type of atom only. have the same number of Subatomic particle with a positive charge and a relative mass of 1. The relative charge of a proton is +1., but different numbers of Uncharged subatomic particle, with a mass of 1 relative to a proton. The relative charge of a neutron is 0. in their Nuclei is the plural of nucleus. The nucleus is the central part of an atom. It contains protons and neutrons, and has most of the mass of the atom.. Isotopes of an element have:
- the same atomic number
- different mass numbers
Three isotopes of hydrogen
All hydrogen atoms contain one proton (and one electron), but they can contain different numbers of neutrons. Hydrogen-1 is the most If there is a lot of something, it is described as being abundant. isotope of hydrogen.
All three isotopes of hydrogen have identical chemical The characteristics of something. In chemistry, chemical properties include the reactions a substance can take part in. Physical properties include colour and boiling point.. This is because the number of Subatomic particle, with a negative charge and a negligible mass relative to protons and neutrons. determines chemical properties, and the atoms of all three isotopes have one electron.
Learn more on isotopes in this podcast.
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Ions
Electrically charged particle, formed when an atom or molecule gains or loses electrons. are charged particles formed when atoms, or groups of atoms, lose or gain electrons:
- positively charged ions form when electrons are lost
- negatively charged ions form when electrons are gained
The charge on an ion is shown as a superscript. For example, an aluminium ion Al3+ carries 3 positive charges. It forms when an aluminium atom loses 3 electrons.
When you calculate the number of subatomic particles in an ion, you need to take into account the number of electrons lost or gained.
Question
The atomic number of a chloride ion, Cl-, is 17 and its mass number is 35. Calculate the number of protons, neutrons and electrons it contains.
- number of protons = 17
- number of electrons = 17 + 1 = 18
- number of neutrons = 35 - 17 = 18