Along a period atomic volume of the elements gradually increases from left to right due to an incerase in the number of valence electrons

Answer

### Step-by-Step Solution:

1. **Understanding the Statement**: The statement claims that along a period, the atomic volume of elements increases from left to right due to an increase in the number of valence electrons.

2. **Analyzing Atomic Volume**: Atomic volume is related to the size of the atom. As we move from left to right across a period in the periodic table, we need to consider how atomic size changes.

3. **Periodic Table Arrangement**: Elements in the periodic table are arranged in order of increasing atomic number. As we move from left to right, the atomic number increases, which means there are more protons in the nucleus.

4. **Effective Nuclear Charge (Z-effective)**: With an increase in protons, the effective nuclear charge (Z-effective) also increases. This means that the nucleus has a stronger positive charge, which pulls the electrons closer to it.

5. **Size of the Atom**: As the electrons are pulled closer to the nucleus due to the increased nuclear charge, the size of the atom decreases. Therefore, atomic volume does not increase; it actually decreases as we move from left to right across a period.

6. **Group 18 Exception**: While atomic volume decreases across the periods up to group 17, group 18 (noble gases) shows a slight increase in atomic volume compared to group 17 due to their unique electron configurations and larger atomic radii.

7. **Conclusion**: Therefore, the statement that "along a period atomic volume of the elements gradually increases from left to right due to an increase in the number of valence electrons" is **false**. Atomic volume actually decreases across a period until group 18.

### Summary:
- The statement is **false**.
- Atomic volume decreases from left to right due to increased nuclear charge pulling electrons closer.
- An exception occurs in group 18 where atomic volume increases slightly.