A neutral atom has the following electronic configuration: `1s^(2)2s^(2)2p^(6)3s^(2)3p^(5)`
How many protons are in the atomic nucleus?

Options

A. 4
B. 12
C. 7
D. 17

Answer

To determine the number of protons in the atomic nucleus of a neutral atom with the given electronic configuration `1s^(2)2s^(2)2p^(6)3s^(2)3p^(5)`, we can follow these steps:

### Step 1: Understand the Electronic Configuration
The electronic configuration provided describes how electrons are distributed in the atom's orbitals. Each term in the configuration indicates the number of electrons in that particular subshell.

### Step 2: Count the Electrons
We need to count the total number of electrons based on the electronic configuration:
- `1s^(2)` has 2 electrons.
- `2s^(2)` has 2 electrons.
- `2p^(6)` has 6 electrons.
- `3s^(2)` has 2 electrons.
- `3p^(5)` has 5 electrons.

Now, let's sum these up:
- Total electrons = 2 (from 1s) + 2 (from 2s) + 6 (from 2p) + 2 (from 3s) + 5 (from 3p)

### Step 3: Calculate the Total
Calculating the total:
- Total electrons = 2 + 2 + 6 + 2 + 5 = 17

### Step 4: Relate Electrons to Protons
In a neutral atom, the number of protons is equal to the number of electrons. Since we have found that there are 17 electrons, we conclude that:
- Number of protons = Number of electrons = 17

### Final Answer
Therefore, the number of protons in the atomic nucleus is **17**.

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