Question

Identify the electronic configuration of an element that belongs to the second long period in the periodic table.

• A. 2, 8, 18,2
• B. 2,8, 18,8
• C. 2,8, 18, 8,2
• D. 2,8,8

Answer 1

The correct option is C

2,8, 18, 8,2

Periodic Table:

1. The periodic chart has two ways of organizing elements: groups and periods.
2. Periods are horizontal rows (across) and groups are vertical columns (down) in the periodic table.
3. Periods 4 and 5 are known as long periods since they each have 18 elements.
4. The fourth period is known as the first long period.
5. The fifth period is the second long period.

Explanation for Correct option: (C) 2,8, 18, 8,2 ;

1. Strontium belongs to period 5. ( second long period)
2. The chemical element strontium has the symbol Sr and the atomic number 38.

Explanation for Incorrect options:

(A) 2, 8, 18,2;

1. Zinc belongs to period 4.
2. Zinc is a chemical element with the atomic number 30 and has the symbol Zn.

(B) 2,8, 18,8;

1. Krypton belongs to period 4.
2. Krypton is an atomic number 36 chemical element having the symbol Kr.

(D) 2,8,8;

1. Argon belongs to period 3.
2. Argon is a chemical element with the atomic number 18 and the symbol Ar.

Thus, from the given electronic configuration only 2,8,18,8,2 configuration belongs to period 5.

Hence, (C) is the correct option.