Question Video: Writing the Chemical Formula of the Magnesium Ion | Nagwa Question Video: Writing the Chemical Formula of the Magnesium Ion | Nagwa

Question Video: Writing the Chemical Formula of the Magnesium Ion Chemistry • First Year of Secondary School

A magnesium atom has the chemical formula Mg. What is the chemical formula of the magnesium ion?

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Video Transcript

A magnesium atom has the chemical formula Mg. What is the chemical formula of the magnesium ion?

A chemical formula is an expression used to represent an atom, ion, or compound. We are told in the question that the chemical formula of a magnesium atom is Mg. We need to determine the chemical formula of the magnesium ion.

An ion is an atomic or molecular particle with a net electric charge. The chemical formula of an ion consists of the chemical formula of the corresponding atom or molecule with the charge written as a superscript to the right of the chemical symbol. So, the chemical formula of the magnesium ion will consist of the chemical symbol for magnesium, Mg, with the charge of the ion written to the right as a superscript.

The location of an element on the periodic table can sometimes help us to determine the most likely charge an ion of that element would have. For example, group one metal ions typically have a charge of one plus, while group two metal ions typically have a charge of two plus. The halogens of group 17 typically form ions with a charge of one minus. Many group 16 elements form ions with a charge of two minus, and some of the group 15 elements are likely to form ions with a charge of three minus.

The element magnesium is found in group two of the periodic table, so a magnesium ion is likely to have a two plus charge. We can write the charge two plus as a superscript to the right of the symbol Mg to complete the chemical formula of the magnesium ion. So the complete chemical formula of the magnesium ion is Mg2+.

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