Two atoms X and Y have 5 and 7 valence electrons. The formula of the compound formed by their combination is

Options

A. X Y
B. X `Y_2`
C. `X Y_3`
D. `X_3 Y`

Answer

To determine the formula of the compound formed by the combination of two atoms X and Y, which have 5 and 7 valence electrons respectively, we can follow these steps:

### Step 1: Identify the Valence Electrons
- Atom X has 5 valence electrons.
- Atom Y has 7 valence electrons.

### Step 2: Determine the Electron Requirements for Stability
- Atom X needs 3 more electrons to complete its octet (8 electrons).
- Atom Y needs 1 more electron to complete its octet.

### Step 3: Analyze the Type of Bond
- Since both atoms need to gain electrons to achieve stability, they will not lose electrons. Instead, they will share electrons.
- This indicates that the bond formed between X and Y will be a covalent bond.

### Step 4: Determine the Number of Atoms Required
- To satisfy the electron requirement of X (which needs 3 electrons), we can use 3 atoms of Y.
- Each Y atom can share 1 electron with X, providing the 3 electrons that X needs to complete its octet.

### Step 5: Write the Molecular Formula
- Since we have 1 atom of X and 3 atoms of Y, the molecular formula for the compound formed will be XY₃.

### Conclusion
The formula of the compound formed by the combination of atoms X and Y is **XY₃**.