Question

An element has its electron configuration as \(2, 8, 1\). Now answer the following questions: 

1. What is the atomic number of this element? 
2. What is the group of this element? 
3. To which period does the element belong? 

Hint:

The atomic number is simply the sum of the electrons in an atom. The group is determined by the number of valence electrons, and the period is determined by the number of electron shells.

Answer 1

• Atomic number: The atomic number is the total number of electrons in an atom. Given the electron configuration \( 2, 8, 1 \), the total number of electrons is \( 2 + 8 + 1 = 11 \). Thus, the atomic number of the element is \( 11 \).
• Group: The group of an element is determined by the number of valence electrons (the electrons in the outermost shell). Since the outermost shell has 1 electron, the element belongs to Group 1, which contains alkali metals.
• Period: The period of an element is determined by the number of electron shells. Since the electron configuration has 3 energy levels (or shells), the element belongs to Period 3.

Correct Answer: 

• The atomic number of the element is \( 2 + 8 + 1 = 11 \).
• The element belongs to Group 1, as it has 1 electron in its outermost shell.
• The element belongs to Period 3, as the electron configuration has 3 energy levels.