Quick answerMagnesium (Mg) is an alkaline earth metal with atomic number 12 and an atomic mass of 24.305 (2023), in group 2, period 3. It was discovered by Joseph Black in 1755. It is used for lightweight alloys for cars and electronics and fireworks and flares. Its electron configuration is [Ne] 3s2.
Magnesium is the lightest structural metal, which is why it shows up in laptop cases, camera bodies, and car parts where every gram counts. It also sits at the heart of every chlorophyll molecule, letting plants turn sunlight into food, and into the magnesium in your diet. Burned, it produces a blinding white light once used in camera flashes and fireworks.
Key facts
| Symbol | Mg |
|---|---|
| Atomic number | 12 |
| Atomic mass | 24.305 (IUPAC standard atomic weight, 2023) |
| Category | alkaline earth metal |
| Group | 2 |
| Period | 3 |
| Block | s-block |
| Electron configuration | [Ne] 3s2 |
| Discovered | Joseph Black, 1755 |
| Uses | lightweight alloys for cars and electronics, fireworks and flares, steel desulfurisation, chlorophyll in plants, dietary supplements |
Overview
Magnesium is the lightest structural metal, strong enough to build with yet about a third lighter than aluminium, which is why it shows up in laptop cases, camera bodies and car parts where every gram counts. It has atomic number 12, an atomic mass of 24.305, and the electron configuration [Ne] 3s2, and it sits in group 2, the alkaline earth metals, in period 3. Joseph Black recognised it as a distinct element in 1755, in the bitter salts of Epsom, and named it after Magnesia, a region of Greece. Magnesium is the eighth most abundant element in Earth's crust, found in minerals such as dolomite and magnesite, and dissolved in seawater, from which it is also extracted. Its most remarkable role is in living things: a single magnesium atom sits at the heart of every chlorophyll molecule, letting plants turn sunlight into food, and your own body needs magnesium for muscles, nerves and bones. Burned, magnesium produces a blinding white light, once used in camera flashes and still used in fireworks and flares. Its alloys lighten cars and aircraft, and its compounds remove sulfur from steel and neutralise stomach acid.
Frequently asked questions
What is magnesium used for?
Magnesium is used in light alloys for cars, laptops, cameras and aircraft, where every gram counts. It is burned in fireworks and flares for a blinding white light, it removes sulfur from steel, and its compounds treat stomach acid. In nature, a magnesium atom sits at the heart of every chlorophyll molecule in plants.
What is the symbol for magnesium?
The chemical symbol for magnesium is Mg, from its name, which comes from Magnesia, a region of Greece where its minerals were found. It has atomic number 12 and a standard atomic mass of 24.305, and it sits in group 2 and period 3. Joseph Black recognised it as a distinct element in 1755.
What is the atomic number of magnesium?
Magnesium has atomic number 12, so it is the twelfth element in the periodic table. Its atom holds twelve protons and twelve electrons, and its standard atomic mass is 24.305. It is an alkaline earth metal in group 2 and period 3, with the electron configuration [Ne] 3s2, two electrons in its outer shell.
Is magnesium a metal?
Yes, magnesium is a metal, an alkaline earth metal in group 2 of the periodic table. It is silvery-white, light and strong, and it is the lightest structural metal, about a third lighter than aluminium. It burns with a blinding white light and reacts with water, so it is handled with care in workshops.
Why is magnesium important for plants?
Magnesium is essential for plants because a single magnesium atom sits at the centre of every chlorophyll molecule, the green pigment that captures sunlight for photosynthesis. Without magnesium, plants cannot make chlorophyll and their leaves turn yellow. Farmers add magnesium to soil and fertiliser to keep crops green and growing.
Quick quiz
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Keep exploring
- Periodic table — all 118 elements
- Beryllium (Be) — another alkaline earth metal, atomic number 4
- Calcium (Ca) — another alkaline earth metal, atomic number 20
- Strontium (Sr) — another alkaline earth metal, atomic number 38
- Barium (Ba) — another alkaline earth metal, atomic number 56
- Radium (Ra) — another alkaline earth metal, atomic number 88
Sources & last updated
- CIAAW — Standard Atomic Weights
- PubChem Periodic Table
- Wikipedia — Timeline of chemical element discoveries
Last updated: . Figures are shown with their year; where sources disagree, the value is left out rather than estimated.