The electronic configuration `1s^(2)2s^(2)2p^(6)3s^(2)3p^ (6)3d^(9)` represents a

Options

A. Metal atom
B. Non-metal atom
C. Non-metallic anion
D. Metallic cation

Explanation

To determine what the electronic configuration `1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(9)` represents, we can follow these steps:

### Step 1: Identify the Total Number of Electrons
The given electronic configuration can be analyzed to find the total number of electrons:
- `1s^2` contributes 2 electrons
- `2s^2` contributes 2 electrons
- `2p^6` contributes 6 electrons
- `3s^2` contributes 2 electrons
- `3p^6` contributes 6 electrons
- `3d^9` contributes 9 electrons

Adding these together:
\[ 2 + 2 + 6 + 2 + 6 + 9 = 27 \text{ electrons} \]

### Step 2: Determine the Element
The total number of electrons corresponds to the atomic number of the element. An atomic number of 27 indicates that the element is cobalt (Co).

### Step 3: Consider the Oxidation State
However, the configuration `3d^(9)` suggests that this is not the neutral atom. The neutral cobalt atom has the configuration:
\[ 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^7 \]
When cobalt loses two electrons to form a cation, it typically loses the two electrons from the `4s` orbital first. Thus, the configuration for cobalt in the +2 oxidation state would be:
\[ 1s^2 2s^2 2p^6 3s^2 3p^6 3d^7 \]
If we consider the possibility of a +1 oxidation state, cobalt would lose one electron from the `4s` orbital, leading to:
\[ 1s^2 2s^2 2p^6 3s^2 3p^6 3d^8 \]
However, the configuration provided is `3d^9`, which suggests that it is likely the configuration of copper (Cu) in the +1 oxidation state, where the neutral copper configuration is:
\[ 1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^{10} \]
Upon losing one electron from the `4s` orbital, we get:
\[ 1s^2 2s^2 2p^6 3s^2 3p^6 3d^9 \]

### Conclusion
Thus, the electronic configuration `1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(9)` represents **copper (Cu) in the +1 oxidation state**.

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