To determine the correct electron configuration for copper (Cu), which has an atomic number of 29, we will follow these steps:
### Step 1: Determine the total number of electrons
Since copper has an atomic number of 29, it has 29 electrons.
### Step 2: Write the expected electron configuration
Following the Aufbau principle, we fill the orbitals in the order of increasing energy levels. The expected electron configuration for 29 electrons would be:
- 1s²
- 2s²
- 2p⁶
- 3s²
- 3p⁶
- 4s²
- 3d⁹
So, the expected configuration is:
\[ 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^2 \, 3d^9 \]
### Step 3: Analyze the stability of the configuration
However, this configuration is not the most stable for copper. The 3d subshell can hold a maximum of 10 electrons, and it is more stable when it is fully filled or half-filled.
### Step 4: Write the actual electron configuration
To achieve greater stability, one electron from the 4s subshell is promoted to the 3d subshell. Therefore, the actual electron configuration for copper is:
\[ 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^1 \, 3d^{10} \]
### Step 5: Conclusion
Thus, the correct electron configuration for copper is:
\[ \text{Argon} \, 4s^1 \, 3d^{10} \]
