Question

Which two elements have the same number of valence electrons? (2 points) Na and Sr Zr and H O and S Mg and P

Answer 1

O and S. hint: valence electrons also matches the group numbers.

Answer 2

Answer: The correct answer is O and S.

Explanation:

Valence electrons are defined as the electrons which are present in outermost shell of an element. It is determined from the electronic configuration of an element.

From the given options:

• Option 1: Na and Sr

The electronic configuration of Na: $1s^22s^22p^63s^1$

Number of valence electrons of this element are 1.

The electronic configuration of Sr: $[Kr]5s^2$

Number of valence electrons of this element are 2.

Hence, these two elements do not have same valence electrons.

• Option 2: Zr and H

The electronic configuration of Zr: $5s^24d^2$

Number of valence electrons of this element are 2.

The electronic configuration of H: $1s^1$

Number of valence electrons of this element are 1.

Hence, these two elements do not have same valence electrons.

• Option 3: O and S

The electronic configuration of O: $1s^22s^22p^4$

Number of valence electrons of this element are 6.

The electronic configuration of S: $[Ne]3s^23p^4$

Number of valence electrons of this element are 6.

Hence, these two elements have same number of valence electrons.

• Option 4: Mg and P

The electronic configuration of Mg: $1s^22s^22p^63s^2$

Number of valence electrons of this element are 2.

The electronic configuration of P: $1s^22s^22p^63s^23p^3$

Number of valence electrons of this element are 5.

Hence, these two elements do not have same valence electrons.

Thus, the correct answer is O and S.