Magnesium is a highly reactive alkaline earth metal denoted by the chemical symbol Mg. It is an essential element for both industrial manufacturing (due to its lightweight strength) and biological health (critical for human nerve function and plant photosynthesis).
The standard atomic mass of Magnesium (Mg) is 24.305 u (unified atomic mass units).
Element Symbol: Mg (Magnesium).
Atomic Number: 12.
Exact Atomic Mass: 24.305 u.
Rounded Mass Number: 24 (used in stoichiometry).
Electron Configuration: [Ne] 3s².
You might wonder why the atomic mass is 24.305 instead of a perfect whole number like 24. This is because atomic mass is calculated as the weighted average of all naturally occurring isotopes of an element.
Magnesium exists in nature as three stable isotopes:
Because Mg-24 is by far the most common, the average mass (24.305) is very close to 24.
For simple high school chemistry calculations, the Mass Number is used, which is simply the sum of protons and neutrons.
Magnesium is located in Group 2 (Alkaline Earth Metals) and Period 3 of the periodic table. Its electron configuration is [Ne] 3s², which explains why it readily loses two electrons to form the Mg²⁺ cation in ionic compounds.
The exact atomic mass of Magnesium (Mg) is 24.305 u, though it is usually rounded to 24 for general chemistry calculations.
The most common isotope of Magnesium has 12 protons and 12 neutrons.
Because magnesium exists as a mixture of three isotopes (Mg-24, Mg-25, and Mg-26). The atomic mass is the weighted average of these three isotopes.
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