How many electrons in Cu have azimuthal quantum number equal to zero?

Explanation

To determine how many electrons in copper (Cu) have an azimuthal quantum number equal to zero, we need to follow these steps:

### Step-by-Step Solution:

1. **Understand the Azimuthal Quantum Number (l)**:
- The azimuthal quantum number (l) indicates the shape of the orbital. For s orbitals, l = 0. Therefore, we are looking for electrons in the s orbitals.

2. **Write the Electronic Configuration of Copper (Cu)**:
- The atomic number of copper is 29, which means it has 29 electrons. The electronic configuration of copper is:
\[ \text{Cu: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^{10} \, 4s^1 \]

3. **Identify the s Orbitals**:
- From the electronic configuration, identify the s orbitals:
- 1s: 2 electrons
- 2s: 2 electrons
- 3s: 2 electrons
- 4s: 1 electron

4. **Count the Electrons in s Orbitals**:
- Now, sum the electrons in all the s orbitals:
\[ 2 \, (from \, 1s) + 2 \, (from \, 2s) + 2 \, (from \, 3s) + 1 \, (from \, 4s) = 7 \]

5. **Final Answer**:
- Therefore, the total number of electrons in copper that have an azimuthal quantum number equal to zero (s orbitals) is **7**.

### Summary:
The number of electrons in Cu with azimuthal quantum number equal to zero is **7**.