Insulators, conductors, and semiconductors can be classified based on their atomic structure and ability to conduct electricity. Insulators have a full outer electron shell and do not conduct electricity well. Conductors have 1-3 electrons in their outer shell and conduct electricity easily. Semiconductors have 4 electrons in their outer shell, allowing some conductivity depending on available electrons (p-type) or holes (n-type). They fall between conductors and insulators.

1. INSULATOR
CONDUCTOR
SEMICONDUCTOR
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2. Every atom wants stability, so it gains, loses
or shares to complete its outermost shell so
it becomes stable

3. Insulator
a material that block or retard the flow of electron.
Plastic Rubber Glass

4. Insulator Atomic Structure
Complete Valance Shell, 5-7 valance electron in its
outermost Shell.

5. Conductor
a material in which electrical charge carriers, usually electrons,
move easily from atom to atom with the application of voltage or
current.
Aluminum Copper Graphite

6. Conductor Atomic Structure
Incomplete outermost shell.
1-3 Valance Electron in it’s outermost shell.

7. Semiconductor
a material that is neither a good conductor nor a good insulator
Silicon germanium
P-type /
N-type

8. Semiconductor Atomic Structure
Incomplete outermost shell.
4 Valance Electron in it’s outermost shell.

9. Energy Band
an enormously large number of energy levels closely spaced in a
very small energy range constitute energy band.
• Valance Band
The highest energy band filled with valence electrons is
called valence band.
• conduction band
The lowest unfiled allowed energy band next to valence band is
called conduction band.

10. • energy gap or bandgap or Forbidden Band
The gap between top of valence band and bottom of conduction
band in which no allowed energy levels for electrons can exist is
called energy gap or band gap.
A position in which
conduction band and valance
band over lap each other is
called overlap region, in this
region electron jump from
valance band to conduction
band where conduction
process is been occurred.

11. Thank you

12. Why gap band is called Forbidden Energy Band?
the electrons do not stay in forbidden gap as there is
no energy state in this region.