An element is placed in 5th period and 3rd group what is its atomic number?

Answer

To find the atomic number of an element placed in the 5th period and 3rd group, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Period and Group**: The element is in the 5th period and 3rd group of the periodic table.

2. **Know the Atomic Number of Inert Gases**: The atomic numbers of the inert gases (noble gases) are essential for this calculation. The inert gases in order are:
- Helium (He) - Atomic number 2
- Neon (Ne) - Atomic number 10
- Argon (Ar) - Atomic number 18
- Krypton (Kr) - Atomic number 36
- Xenon (Xe) - Atomic number 54
- Radon (Rn) - Atomic number 86

3. **Locate the Inert Gas in the 4th Period**: The inert gas in the 4th period is Krypton (Kr), which has an atomic number of 36.

4. **Calculate the Atomic Number of the Element**: Since the element is in the 5th period and 3rd group, we need to add 3 to the atomic number of Krypton:
\[ \text{Atomic number of the element} = 36 + 3 = 39 \]

5. **Conclusion**: The atomic number of the element in the 5th period and 3rd group is 39.

### Final Answer:
The atomic number of the element is **39**.

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