Writen the atomic number of the element present in the fourth period and eighth group of the Modern periodic table.

Answer

To find the atomic number of the element present in the fourth period and eighth group of the Modern periodic table, we can follow these steps:

### Step 1: Identify the Period
The question specifies the fourth period. In the periodic table, the periods are horizontal rows. The fourth period includes elements that have their outermost electrons in the fourth energy level (n=4).

### Step 2: Identify the Group
The question also specifies the eighth group. In the periodic table, groups are vertical columns. The eighth group corresponds to the transition metals, specifically the elements that have partially filled d-orbitals.

### Step 3: Determine the Electronic Configuration
For the fourth period, the electronic configuration starts with filling the 4s orbital followed by the 3d orbitals. The general filling order for the fourth period is:
- 4s: 2 electrons (4s²)
- 3d: up to 10 electrons (3d¹ to 3d¹⁰)

Since we are looking for the eighth group, we need to consider the transition metals, which start filling the d-orbitals.

### Step 4: Count the Electrons
The eighth group in the fourth period corresponds to the element with the electronic configuration of:
- 4s² 3d⁶

### Step 5: Find the Atomic Number
To find the atomic number, we need to sum the number of electrons:
- 2 electrons from 4s²
- 6 electrons from 3d⁶

Total = 2 + 6 = 8 electrons in the fourth period. However, we also need to account for the previous noble gas configuration (argon, with atomic number 18). Therefore, the total atomic number is:
- Atomic number = 18 (from argon) + 8 = 26

### Conclusion
The atomic number of the element present in the fourth period and eighth group of the Modern periodic table is **26**. This element is Iron (Fe).

---