Elements with `Z =107, 108` and `109` have been made recently. Indicate the groups to which they belong.

Explanation

To determine the groups of the elements with atomic numbers 107, 108, and 109, we will analyze their electron configurations step by step.

### Step 1: Determine the Electron Configuration of Element 107
1. Start with the nearest noble gas preceding element 107, which is Radon (Rn, atomic number 86).
2. The electron configuration of Radon is:
\[ [Rn] = 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^2 4f^{14} 5d^{10} 6p^6 \]
3. For element 107, we add the remaining electrons:
- After Radon, we have 21 electrons left to account for (107 - 86 = 21).
- The next electrons fill the 7s and 5f orbitals first:
- 7s: 2 electrons
- 5f: 14 electrons (for element 103 to 106)
- 6d: 5 electrons (for element 107)
4. Therefore, the electron configuration for element 107 is:
\[ [Rn] 7s^2 5f^{14} 6d^5 \]

### Step 2: Determine the Group for Element 107
1. Element 107 has 5 d-electrons (from the 6d subshell) and 2 s-electrons (from the 7s subshell).
2. To find the group number for d-block elements, we add the number of d-electrons to the number of s-electrons:
\[ \text{Group} = \text{d-electrons} + \text{s-electrons} = 5 + 2 = 7 \]
3. Therefore, element 107 belongs to **Group 7**.

### Step 3: Determine the Electron Configuration of Element 108
1. Following the same method, for element 108:
- We have 20 electrons left after Radon (108 - 86 = 22).
- Fill the 7s and 5f first:
- 7s: 2 electrons
- 5f: 14 electrons
- 6d: 6 electrons (for element 108)
2. The electron configuration for element 108 is:
\[ [Rn] 7s^2 5f^{14} 6d^6 \]

### Step 4: Determine the Group for Element 108
1. Element 108 has 6 d-electrons and 2 s-electrons.
2. Adding these gives:
\[ \text{Group} = 6 + 2 = 8 \]
3. Therefore, element 108 belongs to **Group 8**.

### Step 5: Determine the Electron Configuration of Element 109
1. For element 109:
- We have 19 electrons left after Radon (109 - 86 = 23).
- Fill the 7s and 5f first:
- 7s: 2 electrons
- 5f: 14 electrons
- 6d: 7 electrons (for element 109)
2. The electron configuration for element 109 is:
\[ [Rn] 7s^2 5f^{14} 6d^7 \]

### Step 6: Determine the Group for Element 109
1. Element 109 has 7 d-electrons and 2 s-electrons.
2. Adding these gives:
\[ \text{Group} = 7 + 2 = 9 \]
3. Therefore, element 109 belongs to **Group 9**.

### Final Answer
- Element 107 belongs to **Group 7**.
- Element 108 belongs to **Group 8**.
- Element 109 belongs to **Group 9**.