Room of the Elements · No. 12

Magnesium (Mg): what kind of element is it?

In short

Magnesium is element number 12, a metal with the symbol Mg. It helps build bones and teeth, and it takes part in many chemical reactions in the body.

Atomic number 1224.31

MgMagnesiumマグネシウム (maguneshiumu)

Atomic weight from the Chemical Society of Japan, “Table of Standard Atomic Weights with Four Significant Figures (2026)”.

An adult body contains about 25 g of magnesium, and 50–60% of it is in the bones.

Magnesium helps form bones and teeth, and it supports enzymes, which speed up chemical reactions in the body, and the making of energy.

It is also one of the nine elements that plants need in large amounts.

The name comes from “magnesia stone,” which is named after a place. Magnesium was discovered in 1808.

In Japanese eighth-grade science, students confirm that a set weight of copper or magnesium can combine with only a limited amount of oxygen.

Q1Bones contain magnesium as well as calcium. Why do you think bones are made of several elements?
Q2How many one-yen coins (1 g each) would weigh the same as 25 g?
Q3Look for things around you that are named after places.

There is no single right answer. Talking it over with someone at home is a good way to learn.

Did you know? — Manganese (Mn) was named after the same place. At first it was called “manganesium.”

Next steps