**CBSE NOTES CLASS 12 PHYSICS **

**CHAPTER 12 ATOMS**

**Hydrogen spectrum series**

Each element emits a spectrum of radiation, which is characteristic of the element itself. The spectrum consists of a set of isolated parallel lines and is called the **line spectrum.**

Hydrogen spectrum contains five series

**Lyman Series - **When electron jumps from n = 2, 3, 4, … to n = 1 orbit, a line of Lyman series is obtained. This series lies in **ultra violet region.**

**Balmer Series - **When electron jumps from n = 3, 4, 5,… to n = 2 orbit, a line of Balmer series is obtained. This series lies in **visual region.**

**Paschen Series -**When electron jumps from n = 4, 5, 6,… to n = 3 orbit, a line of Paschen series is obtained. This series lies in **infrared region.**

**Brackett Series -**When electron jumps from n = 5,6, 7…. to n = 4 orbit, a line of Brackett series is obtained. This series lies in **infrared region.**

**Pfund Series -**When electron jumps from n = 6,7,8, … to n = 5 orbit, a line of Pfund series is obtained. This series lies in **infrared region.**

Emission lines in the spectrum of hydrogen