Assertion: Lithium (Li) has 1 valence electron.

Reason: The number of electrons in the outermost (valence) shell are called the valence electrons.

A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

C. Assertion is correct but Reason is incorrect

D. Both Assertion and Reason are incorrect

The statement regarding lithium and its valence electron is indeed an interesting topic in chemistry. Let's break it down to understand the assertion and the reasoning behind it.

Understanding Lithium's Electron Configuration

Lithium (Li) is the third element on the periodic table, and its atomic number is 3. This means it has three electrons. The arrangement of these electrons is crucial for determining its chemical properties, particularly its reactivity and bonding behavior.

Valence Electrons Explained

Valence electrons are the electrons located in the outermost shell of an atom. They play a significant role in chemical bonding and reactions. For lithium, the electron configuration can be represented as:

• 1s² 2s¹

This notation indicates that lithium has two electrons in its first shell (1s²) and one electron in its second shell (2s¹). The single electron in the outermost shell (2s¹) is what we refer to as a valence electron.

Evaluating the Assertion and Reason

Now, let's analyze the assertion and the reason:

• Assertion: Lithium has 1 valence electron.
• Reason: The number of electrons in the outermost (valence) shell are called the valence electrons.

Both statements are accurate. Lithium indeed has one valence electron, and the definition of valence electrons is correctly stated in the reason. Therefore, the reason provides a proper explanation for the assertion.

Conclusion on the Options

Given this analysis, the correct choice would be:

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

This choice reflects the truth of both statements and their logical connection. Understanding these concepts is fundamental in chemistry, as they help explain how elements interact and form compounds.