|Atom||The unit particle of an element|
|Proton Number||The number of protons in one atom of an element|
|Nucleon Number||The number of protons and neutrons in an atom of an element|
|Isotopes||Atoms of the same element, that have different number of neutrons|
An atom is the simplest unit of an element. It consists of:
- A nucleus : containing protons and neutrons
- Several electrons orbiting the nucleus, arranged in energy levels or shells
|Particle||Relative mass||Relative charge|
Every atom has equal number of protons and electrons; hence the atom has no overall charge!
Structure of an atom
<Image for labelled structure of an atom here>
Isotopes are atoms with different nucleon numbers of the same element.
To make that a little simple, isotopes are atoms with same number of protons, and different number of neutrons.
Isotopes are usually written in the following format:
|A||is the nucleon number|
|Z||is the proton number|
|X||is the symbol of the element|
Let’s consider the following example:
|Isotopes of Hydrogen|
As you can see, the different atoms of hydrogen all have one proton and one electron but the numbers of neutrons are different.
Some isotopes are radioactive; for example, in the above example, tritium is radioactive whereas the other 2 are not. The nuclei of radioactive isotopes are unstable and give off radiation. Take a look at an example below, focusing on radioactive isotopes of uranium:
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