The first ionization energy for in kJ `"mol"^(-1)` H, Li, F. Na has one of the following values 1681, 520, 1312, 495. Which of these values corresponds to that of hydrogen?

Options

A. 1681
B. 1312
C. 520
D. 495

Explanation

To determine the first ionization energy of hydrogen from the given values, we can follow these steps:

### Step 1: Understand Ionization Energy
Ionization energy is the energy required to remove an electron from an isolated gaseous atom. The first ionization energy refers to the energy needed to remove the outermost electron.

### Step 2: Analyze the Given Elements
The elements provided are:
- Hydrogen (H)
- Lithium (Li)
- Fluorine (F)
- Sodium (Na)

### Step 3: Compare Ionization Energies
We need to understand the trends in ionization energy:
- **Down a group**: Ionization energy decreases (e.g., Na < Li).
- **Across a period**: Ionization energy increases (e.g., H < He, Li < Be).

### Step 4: Identify the Elements' Position
- **Hydrogen** is at the top of Group 1 (alkali metals) and has a relatively high ionization energy compared to other alkali metals.
- **Lithium** is in Group 1, Period 2, and has a lower ionization energy than hydrogen.
- **Fluorine** is in Group 17 (halogens) and has a very high ionization energy due to its high electronegativity and the need to gain an electron.
- **Sodium** is in Group 1, Period 3, and has the lowest ionization energy among these elements.

### Step 5: Evaluate the Given Values
The given ionization energy values are:
- 1681 kJ/mol
- 520 kJ/mol
- 1312 kJ/mol
- 495 kJ/mol

### Step 6: Assign Values Based on Trends
- **Sodium (Na)** will have the lowest ionization energy: **495 kJ/mol**.
- **Lithium (Li)** will have a slightly higher value than sodium: **520 kJ/mol**.
- **Fluorine (F)** will have the highest ionization energy: **1681 kJ/mol**.
- The remaining value, **1312 kJ/mol**, corresponds to **Hydrogen (H)**.

### Conclusion
Thus, the first ionization energy of hydrogen corresponds to **1312 kJ/mol**.