Question

an atomic anion with a charge of -1 has the following electron configuration: ar4s²3d¹⁰4p⁶ what is the chemical symbol for the ion? how many electrons does the ion have? how many 3d electrons are in the ion?

Explanation:

Part 1: Chemical Symbol of the Ion

Step 1: Find electrons in Ar

Argon (\( \text{Ar} \)) has an atomic number of 18, so it has 18 electrons.

Step 2: Calculate total electrons in ion

The electron configuration of the ion is \( [\text{Ar}] 4s^2 3d^{10} 4p^6 \). Add electrons from each part: \( 18 + 2 + 10 + 6 = 36 \) electrons.

Step 3: Determine neutral atom's electrons

The anion has a charge of -1, meaning it gained 1 electron. So the neutral atom has \( 36 - 1 = 35 \) electrons (and protons, so atomic number 35).

Step 4: Identify the element

Atomic number 35 is bromine (Br). The anion is \( \text{Br}^- \).

Part 2: Number of Electrons in the Ion

Step 1: Sum electrons from configuration

As calculated before, \( [\text{Ar}] \) (18) + \( 4s^2 \) (2) + \( 3d^{10} \) (10) + \( 4p^6 \) (6) = \( 18 + 2 + 10 + 6 = 36 \).

Part 3: Number of 3d Electrons in the Ion

Step 1: Extract 3d electrons

From the configuration \( 3d^{10} \), the exponent is 10, so there are 10 3d electrons.

Answer:

s:

• Chemical symbol for the ion: \( \text{Br}^- \)
• Number of electrons in the ion: 36
• Number of 3d electrons in the ion: 10