To determine the correct order of first ionization potential among the elements Be (beryllium), B (boron), and C (carbon), we can follow these steps:
### Step 1: Understand Ionization Potential
Ionization potential (or ionization energy) is the minimum amount of energy required to remove an electron from an isolated gaseous atom.
**Hint:** Remember that ionization energy increases with effective nuclear charge and decreases with atomic size.
### Step 2: Analyze the Position of Elements
Beryllium (Be), boron (B), and carbon (C) are located in the second period of the periodic table. As we move from Be to C, the atomic number increases, which means more protons and electrons.
**Hint:** Elements in the same period have the same number of electron shells, but the number of protons increases.
### Step 3: Consider the Electronic Configuration
- **Beryllium (Be)**: Atomic number 4, electronic configuration is 1s² 2s².
- **Boron (B)**: Atomic number 5, electronic configuration is 1s² 2s² 2p¹.
- **Carbon (C)**: Atomic number 6, electronic configuration is 1s² 2s² 2p².
**Hint:** Look for filled and half-filled subshells; they can influence ionization energy.
### Step 4: Compare Ionization Energies
- **Beryllium** has a fully filled 2s subshell, making it more stable and requiring more energy to remove an electron.
- **Boron** has one electron in the 2p subshell, which is easier to remove compared to the fully filled 2s subshell of beryllium.
- **Carbon** has two electrons in the 2p subshell. Although it has a higher nuclear charge than boron, the presence of two electrons in the same subshell leads to increased electron-electron repulsion, making it easier to remove an electron compared to beryllium.
**Hint:** Remember that a fully filled subshell is more stable than a partially filled one.
### Step 5: Establish the Order of Ionization Potential
Based on the above analysis:
- The ionization potential of carbon (C) will be the highest, followed by beryllium (Be), and then boron (B).
Thus, the correct order of first ionization potential is:
**C > Be > B**
### Final Answer
The correct order of first ionization potential among Be, B, and C is:
**C > Be > B**
