Question

The number of valence electrons present in an element with atomic number \(117\) is

• A. \(7\)
• B. \(8\)
• C. \(6\)
• D. \(5\)

Hint:

For main-group elements, the group number often indicates the number of valence electrons. Group \(17\) elements have \(7\) valence electrons.

Answer 1

The Correct Option is A

Step 1: Identify the element with atomic number 117.
Element 117 is Tennessine (Ts), a synthetic element in Period 7, Group 17 (the halogens).
Step 2: Write the electronic configuration.
For Z = 117, the configuration follows the Aufbau principle through Period 7. The outermost electrons fill the 7p subshell. The configuration ends in: $[Rn] 5f^{14} 6d^{10} 7s^2 7p^5$.
Step 3: Identify the valence shell.
The valence shell is $n = 7$, and it contains electrons in 7s and 7p subshells: $7s^2 7p^5$.
Step 4: Count the valence electrons.
Valence electrons = electrons in 7s + electrons in 7p = $2 + 5 = 7$.
Step 5: Confirm using group number.
Group 17 elements (halogens) always have 7 valence electrons. Tennessine belongs to Group 17, confirming 7 valence electrons.
Step 6: Cross-check with the halogen family.
F, Cl, Br, I, At, and Ts all have 7 valence electrons ($ns^2 np^5$). This is the defining feature of halogens.
\[ \boxed{7 \text{ valence electrons}} \]