In the modern periodic table, the place of the element with atomic number 31 is in:

Options

A. s-block
B. d-block
C. p-block
D. f–block

Answer

To determine the place of the element with atomic number 31 in the modern periodic table, we can follow these steps:

### Step 1: Identify the Element
The element with atomic number 31 is Gallium (Ga).

### Step 2: Write the Electronic Configuration
To find out where Gallium is located in the periodic table, we need to write its electronic configuration. The atomic number 31 means it has 31 electrons. The electronic configuration can be written as follows:
- 1s² 2s² 2p⁶ (total 10 electrons)
- 3s² 3p⁶ (total 18 electrons)
- 4s² (total 20 electrons)
- 3d¹⁰ (total 30 electrons)
- 4p¹ (total 31 electrons)

So, the complete electronic configuration of Gallium is:
\[ \text{1s}^2 \, \text{2s}^2 \, \text{2p}^6 \, \text{3s}^2 \, \text{3p}^6 \, \text{4s}^2 \, \text{3d}^{10} \, \text{4p}^1 \]

### Step 3: Determine the Block
In the modern periodic table, elements are categorized into blocks based on the subshell that is being filled with the last electron. The last electron of Gallium enters the 4p subshell.

### Step 4: Locate the Period and Group
Gallium is in the 4th period (as the highest principal quantum number n is 4) and is located in Group 13 (as it is in the p-block and is the first element in the p-block after the transition metals).

### Conclusion
Therefore, the element with atomic number 31, Gallium, is located in the **p-block** of the modern periodic table.

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