An element X which occurs in the second short period has an outer electronic structure `s^2p^1` What are the formula and acid -base character of its oxides ?

Options

A. `XO_3` , basic
B. `X_2O_3` , basic
C. `X_2O_3` , amphoteric
D. `XO_2` , acidic

Answer

To solve the question about the element X with an outer electronic structure of `s²p¹`, we will follow these steps:

### Step 1: Identify the Element
The outer electronic configuration `s²p¹` indicates that the element is in the p-block of the periodic table. Since it is mentioned that the element occurs in the second short period, we need to look for elements in the second period that have this configuration.

- The second period of the periodic table consists of the following elements:
- Lithium (Li) - 1s² 2s¹
- Beryllium (Be) - 1s² 2s²
- Boron (B) - 1s² 2s² 2p¹
- Carbon (C) - 1s² 2s² 2p²
- Nitrogen (N) - 1s² 2s² 2p³
- Oxygen (O) - 1s² 2s² 2p⁴
- Fluorine (F) - 1s² 2s² 2p⁵
- Neon (Ne) - 1s² 2s² 2p⁶

From this list, we can see that the element with the configuration `s²p¹` is **Aluminum (Al)**, which has an atomic number of 13.

### Step 2: Determine the Formula of its Oxide
Aluminum typically forms an oxide by combining with oxygen. The valency of aluminum is +3 (it loses three electrons), and the valency of oxygen is -2. To find the formula of the oxide, we can use the crisscross method for combining the valencies:

- Aluminum (Al) has a valency of 3.
- Oxygen (O) has a valency of 2.

Using the crisscross method:
- The formula will be Al₂O₃ (two aluminum atoms for every three oxygen atoms).

### Step 3: Determine the Acid-Base Character of its Oxide
The oxide of aluminum, Al₂O₃, is known to be **amphoteric**. This means it can react with both acids and bases.

1. **As a Base**:
- When aluminum oxide reacts with hydrochloric acid (HCl), it forms aluminum chloride (AlCl₃) and water (H₂O):
\[ Al_2O_3 + 6HCl \rightarrow 2AlCl_3 + 3H_2O \]

2. **As an Acid**:
- When aluminum oxide reacts with sodium hydroxide (NaOH), it forms sodium aluminate (NaAlO₂) and water:
\[ Al_2O_3 + 2NaOH + 3H_2O \rightarrow 2NaAlO_2 + 3H_2O \]

Since aluminum oxide can react with both acids and bases, it is classified as amphoteric.

### Final Answer
- The formula of the oxide is **Al₂O₃**.
- The acid-base character of its oxide is **amphoteric**.

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