Respuesta :
The expression shows one way to find the number of valence electrons in one atom of magnesium is (12-8)-2.
What is valence electrons?
A valence electron is an electron in the outer shell associated with an atom, and that can participate in the formation of a chemical bond if the outer shell is not closed; in a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair
What is shell arrangement of electrons for all elements?
There is a 2-8-8 rule for these elements. The first shell is filled with 2 electrons, the second is filled with 8 electrons, and the third is filled with 8. You can see that sodium (Na) and magnesium (Mg) have a couple of extra electrons. They, like all atoms, want to be happy.
According to the question
Atomic number of alkaline earth metal Magnesium = 12
Now ,
Arrange its electron in shells
as Mg have electrons = 12
According to the rule 2-8-8 for electron arrangement
1st shell = 2
2nd shell = 8
3rd shell = 2
Therefore,
the number of valence electrons in one atom of magnesium is 2 .
Hence, the expression shows one way to find the number of valence electrons in one atom of magnesium is (12-8)-2.
To know more about valence electrons here:
https://brainly.com/question/12717954
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