Question

Which element has six valence electrons in each of its atoms in the ground state?

(1)Se
(2)As
(3)Kr
(4)Ga

Answer 1

Answer : The correct option is, (1) Se

Explanation :

Electronic configuration : It is defined as the representation of electrons around the nucleus of an atom.

Number of electrons in an atom are determined by the electronic configuration.

Atomic number : It is defined as the number of electrons or number of protons present in a neutral atom.

(1) The given atom is, selenium (Se)

Atomic number of Se = 34

Number of electrons = 34

The electronic configuration of selenium atom is,

`1s^22s^22p^63s^23d^(10)4s^24p^4`

Number of valance electrons = 6

(2) The given atom is, arsenic (As)

Atomic number of As = 33

Number of electrons = 33

The electronic configuration of arsenic atom is,

`1s^22s^22p^63s^23d^(10)4s^24p^3`

Number of valance electrons = 5

(3) The given atom is, krypton (Kr)

Atomic number of Kr = 36

Number of electrons = 36

The electronic configuration of krypton atom is,

`1s^22s^22p^63s^23d^(10)4s^24p^6`

Number of valance electrons = 8

(4) The given atom is, gallium (Ga)

Atomic number of Ga = 31

Number of electrons = 31

The electronic configuration of gallium atom is,

`1s^22s^22p^63s^23d^(10)4s^24p^1`

Number of valance electrons = 3

Hence, from this we conclude that the selenium element has six valence electrons in each of its atoms in the ground state.

Answer 2

Answer is: selenium (Se).
1) electron configuration: ₃₄Se 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4sp⁴.
2) ₃₃As 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4sp³.
3) ₃₆Kr 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4sp⁶.
4) ₃₁Ga 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4sp¹.
Valence electrons of selenium are 4s²4sp⁴.