Shell Model of Oxygen

Physical Environment > Shell Model of Oxygen

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An oxygen nucleus has 8 protons. Therefore it can attract 8 electrons.
The first 2 electrons fill the first shell. The next 6 electrons go into the second shell. This shell can hold a maximum of 8 electrons. So it is 2 electrons short of a full shell.
Oxygen can therefore share 2 electrons with other atoms, so it can form 2 covalent bonds.
In this diagram we see an oxygen atom sharing electrons with two hydrogen atoms to form a water molecule.