Each coinage metal has

Options

A. 2 electrons in the valence shell
B. 8 electrons in the penultimate shell
C. 8 electrons in the outermost shell
D. 18 electrons in the penultimate shell

Answer

To solve the question regarding the electron configuration of coinage metals, we will analyze the electronic configurations of copper, silver, and gold, which are the primary coinage metals. We will then evaluate the options provided.

### Step-by-Step Solution:

1. **Identify Coinage Metals**: The coinage metals are copper (Cu), silver (Ag), and gold (Au). These metals are known for their use in making coins.

2. **Determine Atomic Numbers**:
- Copper (Cu) has an atomic number of 29.
- Silver (Ag) has an atomic number of 47.
- Gold (Au) has an atomic number of 79.

3. **Write Electronic Configurations**:
- **Copper (Cu)**:
- Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s¹
- Shell Distribution:
- 1st shell: 2 electrons
- 2nd shell: 8 electrons
- 3rd shell: 18 electrons
- 4th shell: 1 electron (valence shell)
- **Silver (Ag)**:
- Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s¹
- Shell Distribution:
- 1st shell: 2 electrons
- 2nd shell: 8 electrons
- 3rd shell: 18 electrons
- 4th shell: 18 electrons
- 5th shell: 1 electron (valence shell)
- **Gold (Au)**:
- Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 5d¹⁰ 6s¹
- Shell Distribution:
- 1st shell: 2 electrons
- 2nd shell: 8 electrons
- 3rd shell: 18 electrons
- 4th shell: 32 electrons
- 5th shell: 18 electrons
- 6th shell: 1 electron (valence shell)

4. **Analyze the Options**:
- **Option A**: 2 electrons in the valence shell - **Incorrect** (only 1 electron in the valence shell for all three metals).
- **Option B**: 8 electrons in the penultimate shell - **Incorrect** (the penultimate shell has 18 electrons for all three metals).
- **Option C**: 8 electrons in the outermost shell - **Incorrect** (only 1 electron in the outermost shell for all three metals).
- **Option D**: 18 electrons in the penultimate shell - **Correct** (the penultimate shell has 18 electrons for copper, silver, and gold).

5. **Conclusion**: The correct answer is **Option D: 18 electrons in the penultimate shell**.