Atomic Radius - Li

- **Definition of Atomic Radius**: Atomic radius is the distance from the nucleus of an atom to the outermost electron shell.

- **Relation to Lithium (Li)**: Lithium is a group 1 element in the periodic table with an atomic number of 3.

- **Trend in Atomic Radius**: Atomic radius generally decreases as you move from left to right across a period in the periodic table due to increasing nuclear charge and stronger attraction between the nucleus and the electrons. However, atomic radius increases as you move down a group in the periodic table because of the addition of new electron shells.

- **Explanation for Lithium (Li)**:
- Lithium has a relatively large atomic radius compared to other elements in the same period (period 2) because it is located in the first group (group 1) of the periodic table.
- Lithium has only 3 electrons and the outermost electron is in the 2nd energy level. This electron experiences less attraction from the nucleus compared to elements with more protons in their nucleus.
- As a result, the atomic radius of lithium is larger compared to elements like helium and beryllium in the same period.

- **Significance of Atomic Radius**: Atomic radius is an important property as it helps in determining the size of atoms which in turn influences various physical and chemical properties of elements.

In conclusion, the atomic radius of lithium (Li) is relatively larger compared to other elements in the same period due to its position in the periodic table and the number of electrons in its outermost shell.