A new electron enters the orbital when:

Options

A. value of n is minimum
B. value of l is minimum
C. value of (n + l) is minimum
D. value of (n + m) is minimum

Explanation

To determine when a new electron enters an orbital, we can follow these steps based on the principles of quantum mechanics and electron configuration:

### Step 1: Understand the Aufbau Principle
The Aufbau principle states that electrons fill atomic orbitals in order of increasing energy. This means that electrons will occupy the lowest energy orbitals first before moving to higher energy levels.

**Hint:** Remember that the Aufbau principle is key to understanding the order in which electrons fill orbitals.

### Step 2: Identify the Quantum Numbers
Each orbital is defined by a set of quantum numbers:
- Principal quantum number (n): Indicates the energy level.
- Azimuthal quantum number (l): Indicates the shape of the orbital.

**Hint:** The principal quantum number (n) and azimuthal quantum number (l) are crucial for determining the energy of an orbital.

### Step 3: Apply the n + l Rule
According to the n + l rule, the energy of an orbital is determined by the sum of its principal quantum number (n) and azimuthal quantum number (l). Orbitals with lower n + l values have lower energy and will be filled first.

**Hint:** Focus on the sum of n and l to find out which orbitals have the lowest energy.

### Step 4: Determine the Minimum Value of n + l
When a new electron enters an orbital, it will do so in the orbital with the lowest n + l value. If two orbitals have the same n + l value, the one with the lower n will be filled first.

**Hint:** Compare the n + l values of different orbitals to find the one with the minimum value.

### Conclusion
Therefore, a new electron enters the orbital when the value of n + l is minimum.

**Final Answer:** The correct option is that a new electron enters the orbital when the value of n + l is minimum.