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Q & A: Magnesium

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Most recent answer: 10/22/2007
Q:
I’m doing a model of a magnesium atom and I can’t find how many netrons, protons, and electrons are in it. Can you help me?
- Krystin Bender (age 12)
Demille, Lakewood CA
A:
Magnesium, in its elemental form, has 12 protons and 12 electrons.

The neutrons are a different matter. Magesium's average atomic mass is 24.305 atomic mass units, but no magnesium atom has exactly this mass.

Atomic masses like the one quoted above are found by taking an average of the masses of each isotope, weighted based on how much of each is present in nature.
An isotope is a compound with the same number of protons and electrons, but different number of neutrons.

The three most natural isotopes of Mg are Mg-24, Mg-25, and Mg-26.

Mg-24 (12 neurtrons) is 78.9%, Mg-25 (13 neutrons) is 10% and Mg-26 (14 neutrons) is 11.01%, of all the Magnesium found in nature. There are also synthetic isotopes, created as byproducts of nuclear decay or intentionally for commercial use, so they aren't included.

So you might account for this isotope problem by saying that about 79% of all Magnesium atoms have 12 neutrons, 12 protons, and 12 electrons.

For further research, I suggest you use the source I used to obtain this information (available at your local library):

Heiserman, David. "Exploring Chemical Elements and Their Compounds". Copyright 1992. Tab-Books/McGraw Hill P.49 - 53

Jason

(published on 10/22/2007)

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