To solve the question step by step, we will analyze the information provided about the elements A, B, C, and D, and derive the required answers.
### Step 1: Identify the Group Numbers
We know the number of valence electrons for each element:
- Element A has 1 valence electron.
- Element B has 3 valence electrons.
- Element C has 5 valence electrons.
- Element D has 7 valence electrons.
In the Modern Periodic Table, the group numbers are assigned based on the number of valence electrons:
- Elements with 1 valence electron belong to **Group 1**.
- Elements with 3 valence electrons belong to **Group 13**.
- Elements with 5 valence electrons belong to **Group 15**.
- Elements with 7 valence electrons belong to **Group 17**.
Thus, the group numbers are:
- Element A: Group 1
- Element B: Group 13
- Element C: Group 15
- Element D: Group 17
### Step 2: Write the Electronic Configuration of B and D
To write the electronic configuration, we need to fill the electrons in the K, L, and M shells according to the rules of electron configuration.
**For Element B (Group 13, 3 valence electrons)**:
- The maximum capacity of the K shell is 2 electrons.
- The maximum capacity of the L shell is 8 electrons.
- Since B has 3 valence electrons, we can fill the shells as follows:
- K shell: 2 electrons
- L shell: 8 electrons
- M shell: 3 electrons
Thus, the electronic configuration of B is:
- **2, 8, 3**
**For Element D (Group 17, 7 valence electrons)**:
- The K shell can hold 2 electrons.
- The L shell can hold 8 electrons.
- The M shell will hold the remaining electrons:
- K shell: 2 electrons
- L shell: 8 electrons
- M shell: 7 electrons
Thus, the electronic configuration of D is:
- **2, 8, 7**
### Step 3: Determine the Molecular Formula of the Compound Formed by B and D
To find the molecular formula of the compound formed when B and D combine, we need to determine their valences:
- The valence of B (with 3 valence electrons) is **+3**.
- The valence of D (with 7 valence electrons) can be calculated as \(8 - 7 = 1\).
Now, we can use the valences to determine the formula:
- B can donate 3 electrons, while D can accept 1 electron.
- To balance the charges, we can cross-multiply the valences:
- B: 1 (from D)
- D: 3 (from B)
Thus, the molecular formula for the compound formed when B and D combine is:
- **BD3**
### Summary of Answers
- Group Numbers:
- A: Group 1
- B: Group 13
- C: Group 15
- D: Group 17
- Electronic Configuration:
- B: 2, 8, 3
- D: 2, 8, 7
- Molecular Formula: BD3
