AP L2 Atomic Structure and particles.ppt

atom discription.

1. Atomic Structure, Conductors, Semiconductor & Insulators

2. CONTENTS
Atomic Structure
Conductors, Semi-conductors and Insulators
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3. ATOMIC STRUCTURE
Matter is made of atoms
Atom(the smallest particle)
Electron(-vely charged particle)
Proton(+vely charged particle)
Neutron (Uncharged particle)
Atomic No. (No of protons)
Atomic Wt. (No of P+N)
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4. ATOMIC STRUCTURE
Orbit: Discrete path followed by electron
Orbit represents discrete energy level
Energy of electrons increases away from Nucleus
Discrete energy levels form energy band
Energy band is called Shell
Shell name
1,2,3,4,5,…..
K,L,M,N,O,…...
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5. ATOMIC STRUCTURE
Maximum number of electrons in each shell
Outermost shell is called valance shell
Electrons in valance shell are called valance electrons
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6. ATOMIC STRUCTURE
Ionization
Process of removal/addition of electron from/to
valance shell, when external energy is gained/lost
by electrons
Resulting +vely charged atom is called +ve ion
More protons than electrons
Resulting -vely charged atom is called -ve ion
Less protons than electrons
Escaped electron is called free electron
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7. WHERE DOES FREE ELECTRON GO?
There is another band called conduction band
Free electrons lie in the conduction band
Gap between valance band and conduction band is
called energy gap.
Energy gap is the amount of energy
required by electron to move from
valance band to conduction band.
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8. CONDUCTORS, SEMI-
CONDUCTORS AND
INSULATORS
In terms of Electrical properties all materials are
classified into three groups
Conductors
Semi-conductors
Insulators
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9. CONDUCTORS, SEMI-
CONDUCTORS AND
INSULATORS
Conductors
Easily conduct current
Examples (Single element material)
Copper (A.No 29)
Silver
Gold
Aluminium
Having one electron in valance band
Valance electrons are loosely bound, can easily become
free electrons.
Movement of free electrons in same direction makeup
current
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10. CONDUCTORS, SEMI-
CONDUCTORS AND
INSULATORS
Insulators
Does not conduct electrical current in normal
conditions
Examples (most insulators are compound rather than
single element material)
Compounds with net charge 0
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11. CONDUCTORS, SEMI-
CONDUCTORS AND
INSULATORS
Semi-conductors
Electrical properties in between conductor and insulator
Examples
Group IVA
Carbon
Germanium
Silicon
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12. COMPARISON W-R-T
ENERGY BANDS
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13. KEY TERMS
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14. ASSIGNMENT 1
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15. ASSIGNMENT 2
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16. 16
Assignment 3

17. ASSIGNMENT 4
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