which of the following elements has the fewest valence electrons? beryllium. boron. carbon. lithium.
The Correct Answer and Explanation is:
Correct Answer: Lithium
Explanation:
Valence electrons are the electrons located in the outermost energy level (or shell) of an atom. These electrons determine how an element reacts chemically and what kind of bonds it forms.
Let’s look at each element and count its valence electrons:
- Lithium (Li) – Atomic number 3
Electron configuration: 1s² 2s¹
Lithium has 1 valence electron in the 2s orbital. - Beryllium (Be) – Atomic number 4
Electron configuration: 1s² 2s²
Beryllium has 2 valence electrons in the 2s orbital. - Boron (B) – Atomic number 5
Electron configuration: 1s² 2s² 2p¹
Boron has 3 valence electrons (2 from 2s and 1 from 2p). - Carbon (C) – Atomic number 6
Electron configuration: 1s² 2s² 2p²
Carbon has 4 valence electrons (2 from 2s and 2 from 2p).
From the above, we can clearly see that lithium has the fewest valence electrons among the given options. It has only one electron in its outermost shell. This is consistent with its placement in Group 1 of the periodic table, known as the alkali metals. Elements in this group are highly reactive and tend to lose that single valence electron easily to form a positive ion.
This single valence electron also explains why lithium, like other alkali metals, is very reactive in chemical reactions, especially with water, and tends to form ionic compounds. Its low number of valence electrons is also the reason it is a good conductor of electricity and has a low melting point relative to other metals.
In conclusion, lithium has the fewest valence electrons among the four listed elements.
