Core Atomic
Structure: Electronic Structure
Slide 20 of 44
Emission spectrum
of Hydrogen & Shells
When the electron in a
hydrogen atom is in the first shell, hydrogen is said to be
in the ground state.
When, after the absorption of
(light or electrical) energy, the electron moves to an
outer shell, the atom is said to be in an excited
state.
Shells are numbered
from inside out, i.e. shell closest to the nucleus is numbered
1, and then 2, 3, 4 etc.
The boundary or
shell where the positive nucleus has no influence over the electron,
the zero potential energy level, is n = ¥.
The electrons found
in the the outermost shell, valence shell,
are referred to as the valence electrons.
–Chemical
properties depend mostly on the number and arrangement of
electrons in the valence shell.
Each shell is a certain
distance from the nucleus.
This distance is a
measure of its potential energy, and therefore the shells are also
referred to as energy levels.