Which of the following elements has the fewest valence electrons? beryllium boron carbon lithium The answer is lithium but someone had the same question and someone answered wrong. Lithium only has on valence electron while beryllium has 2, boron has 3 and carbon has 4 making lithium the correct answer
The Correct Answer and Explanation is:
Correct Answer: Lithium
Lithium has the fewest valence electrons among the elements listed: beryllium, boron, carbon, and lithium. The number of valence electrons an element has is determined by its group in the periodic table. Valence electrons are the outermost electrons of an atom and are involved in chemical bonding.
Let us examine each element:
- Lithium (Li) is in Group 1 of the periodic table. Elements in Group 1 have one valence electron. This single electron is in the second energy level, specifically in the 2s orbital. Lithium’s electron configuration is 1s² 2s¹, and the one electron in the 2s orbital is the valence electron.
- Beryllium (Be) is in Group 2. It has two valence electrons. Its electron configuration is 1s² 2s². The two electrons in the 2s orbital are in the outer shell, making them valence electrons.
- Boron (B) is in Group 13. It has three valence electrons. Its configuration is 1s² 2s² 2p¹, where the two 2s electrons and one 2p electron are all in the second shell, forming the valence electrons.
- Carbon (C) is in Group 14. It has four valence electrons. Its configuration is 1s² 2s² 2p², with all four electrons in the second shell contributing to chemical bonding.
Since lithium has only one valence electron, it is the correct answer. Valence electrons determine how atoms interact with one another, and having fewer valence electrons generally means the atom is more likely to lose electrons to achieve a stable configuration. This is why lithium, with just one valence electron, is very reactive and commonly forms positive ions in reactions.
