Answer:
D. Ar.
Explanation:
The<em> </em><em>electron configuration</em><em> of the atom reflects how the electrons are distributed among the various atomic orbitals</em>. Just as for neutral atoms, we use the Pauli exclusion principle and Hund’s rule in writing the ground-state electron configurations of cations and anions.
<u>Ions formed from atoms of most representative elements have the noble-gas outer electron configuration of ns²np⁶.</u> In the formation of a cation from the atom of a representative element, one or more electrons are removed from the highest occupied n shell. The electron configuration of calcium and its ion is as follows:
Ca: [Ar]4s² Ca²⁺ : [Ar]
Answer:
The mass is 20, 89 grams of He.
Explanation:
We calculate the weight of 1 mol of He, from the atomic weight of each element obtained from the periodic table: Weight 1 mol He= 4, 0020602 g. 1 mol He-----4, 0020602 g. 5,22 mol He---x= (5,22 mol He x4, 0020602 g)/ 1 mol He= 20, 89 g
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Answer D, aluminum, because the other choices are elements.