Electronic configuration calcium atom can be written as

Options

A. [Ne] `4p^(2)`
B. [Ar] `4s^(2)`
C. [Ne]`4s^(2)`
D. [Kr]`4p^(2)`

Explanation

To determine the electronic configuration of a calcium atom (Ca), we need to follow these steps:

### Step 1: Identify the Atomic Number
The atomic number of calcium is 20. This means that a neutral calcium atom has 20 electrons.

**Hint:** The atomic number of an element tells you the number of protons and, in a neutral atom, the number of electrons.

### Step 2: Fill the Electron Shells
We will fill the electron shells according to the Aufbau principle, which states that electrons occupy the lowest energy orbitals first.

1. **1s Orbital:** Can hold a maximum of 2 electrons.
- Fill 1s: 1s² (2 electrons)

2. **2s Orbital:** Can hold a maximum of 2 electrons.
- Fill 2s: 2s² (2 electrons)

3. **2p Orbital:** Can hold a maximum of 6 electrons.
- Fill 2p: 2p⁶ (6 electrons)

4. **3s Orbital:** Can hold a maximum of 2 electrons.
- Fill 3s: 3s² (2 electrons)

5. **3p Orbital:** Can hold a maximum of 6 electrons.
- Fill 3p: 3p⁶ (6 electrons)

6. **4s Orbital:** Can hold a maximum of 2 electrons.
- Fill 4s: 4s² (2 electrons)

### Step 3: Write the Complete Electronic Configuration
Now, we can combine all the filled orbitals to write the complete electronic configuration of calcium:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

### Step 4: Use Noble Gas Notation
To simplify the electronic configuration, we can use the noble gas notation. The nearest noble gas before calcium is argon (Ar), which has an atomic number of 18 and an electronic configuration of 1s² 2s² 2p⁶ 3s² 3p⁶.

Thus, we can write the electronic configuration of calcium as:
- [Ar] 4s²

### Final Answer
The electronic configuration of a calcium atom can be written as:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² or [Ar] 4s².

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