The melting point of the group 1 elements _______ and group 17 elements________ down the group.

Options

A. Increases, decreases
B. Decreases, increases
C. Decreases, decreases
D. Increases, increases

Answer

To answer the question regarding the melting points of group 1 and group 17 elements down the group, we can analyze the trends based on their properties.

### Step-by-Step Solution:

1. **Identify Group 1 Elements**:
- Group 1 elements are known as alkali metals (e.g., lithium, sodium, potassium, etc.).

2. **Trend in Melting Points for Group 1 Elements**:
- The melting point of alkali metals **decreases down the group**.
- This trend occurs because as we move down the group, the atomic size increases.
- Larger atoms have weaker metallic bonds due to the increased distance between the nucleus and the delocalized electrons.
- Weaker metallic bonds result in lower melting points.

3. **Identify Group 17 Elements**:
- Group 17 elements are known as halogens (e.g., fluorine, chlorine, bromine, iodine, etc.).

4. **Trend in Melting Points for Group 17 Elements**:
- The melting point of halogens **increases down the group**.
- This is because as we move down the group, the size of the atoms increases, leading to stronger van der Waals forces (dispersion forces).
- Stronger intermolecular forces result in higher melting points.

5. **Conclusion**:
- Therefore, the melting point of group 1 elements **decreases** down the group, while the melting point of group 17 elements **increases** down the group.

### Final Answer:
The melting point of the group 1 elements **decreases** and group 17 elements **increases** down the group.

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