Predict which of the following statements are true or false.
Phosphorus (Z = 15) has three unpaired electrons.

Answer

To determine whether the statement "Phosphorus (Z = 15) has three unpaired electrons" is true or false, we will follow these steps:

### Step 1: Determine the Atomic Number
Phosphorus has an atomic number (Z) of 15. This means it has 15 electrons.

### Step 2: Write the Electronic Configuration
We need to write the electronic configuration of phosphorus. The electrons are filled in the following order:
- 1s: 2 electrons
- 2s: 2 electrons
- 2p: 6 electrons
- 3s: 2 electrons
- 3p: 3 electrons

Thus, the electronic configuration of phosphorus is:
\[ \text{1s}^2 \, \text{2s}^2 \, \text{2p}^6 \, \text{3s}^2 \, \text{3p}^3 \]

### Step 3: Identify the Electron Shells and Orbitals
In the configuration:
- The 1s, 2s, and 2p orbitals are fully filled.
- The 3s orbital has 2 electrons (paired).
- The 3p orbital has 3 electrons.

### Step 4: Determine the Number of Unpaired Electrons
In the 3p orbital, we have 3 electrons. According to Hund's rule, each of the three p orbitals (px, py, pz) will each get one electron before any pairing occurs. Therefore, all three electrons in the 3p orbital are unpaired.

### Conclusion
Since phosphorus has 3 unpaired electrons, the statement "Phosphorus (Z = 15) has three unpaired electrons" is **True**.

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