Question

1. which of the following noble gas configurations represents the element bromine at ground state? clear all ar 4s² 4d¹⁰ 4p⁵ ar 4s²3d¹⁰ 4p⁵ ar 4s²3d¹⁰ 4p⁶ ar 4s¹ 4d¹⁰ 4p⁵

Explanation:

Step1: Recall bromine's atomic number

Bromine has an atomic number of 35. Argon ([Ar]) has an atomic number of 18.

Step2: Write electron - configuration after [Ar]

After the [Ar] core (18 electrons), we need to account for 35 - 18=17 more electrons. The order of filling is 4s, 3d, 4p. The 4s sub - shell fills first (2 electrons), then the 3d sub - shell (10 electrons), and then the 4p sub - shell. So the configuration after [Ar] is $4s^{2}3d^{10}4p^{5}$.

Answer:

$[\text{Ar}]4s^{2}3d^{10}4p^{5}$