The periodic table was arranged so that properties could be predicted for elements, just by looking at their position in relation to other elements. Consider two of the group 2 elements, Magnesium and Strontium. Which statement accurately describes the difference in the atomic radius?

Magnesium has a larger atomic radius because it has a lesser effective nuclear charge.

Strontium has a larger atomic radius because it contains more protons. Magnesium has a smaller atomic radius because it has 2 valence electrons. Strontium has a larger atomic radius because Strontium has more shells of electrons than Magnesium does.

Question

Chemistry

Bronson Hays

7 February, 02:23

The periodic table was arranged so that properties could be predicted for elements, just by looking at their position in relation to other elements. Consider two of the group 2 elements, Magnesium and Strontium. Which statement accurately describes the difference in the atomic radius?

Magnesium has a larger atomic radius because it has a lesser effective nuclear charge.

Strontium has a larger atomic radius because it contains more protons. Magnesium has a smaller atomic radius because it has 2 valence electrons. Strontium has a larger atomic radius because Strontium has more shells of electrons than Magnesium does.

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Answers (1)

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Michael Reid · Answer 1

Strontium has a larger atomic radius because it has more shells of electrons than magnesium does.

Mg is in Period 3 and Sr is in Period 5. Thus, Sr has two more shells of electrons than Mg.

Each shell is bigger than the one before it, so Sr has a larger atomic radius than Mg.

Both Sr and Mg have the same number of valence electrons, so they are not a factor in determining the atomic radius.

The nucleus is so small compared to the size of an electron shell that its size is not a factor in determining the atomic radius.