Question

What do you notice at the end of each electron configuration of these elements(Li, Na, and K)? ​

Answer 1

Similarities of electronic configuration of Li, Na and K:

• First of all, let's write the electronic configuration of the given elements.

Li : 1s² 2s¹ (2, 1)

Na : 1s² 2s² 2p⁶ 3s¹ (2, 8, 1)

K : 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ (2, 8, 8, 1)

• From the configurations, we can say:

ALL THE GIVEN ELEMENTS HAVE 1 VALENCE ELECTRON !

• Lithium (Li) has 2s¹ as valence electron, Sodium (Na) has 3s¹ as valence electron and Potassium (K) has 4s¹ as valence electron.

• That is the reason, these elements have been placed in Group 1 of the Modern Periodic Table.

• These elements are also known as ALKALI METALS.

$\star$ Hope It Helps.