HOW ELECTRONS BEHAVE >:D
Nature of light
Christian Huygen (1629-1695)
-stated that light, like sound, is a wave motion
***
His idea met many opposite
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> Sir Isaac Newton (1647-1727)
- one of the GIANTS in science who opposed the idea [lyt doz nut trabel n wabe mosyon >:( ]
- formulated his own particle theory of light
Isaac's Theory of Light :3
Light is a very small particle which travels in straight lines.
(Newtonian Theory of the Nature of Light)
> Maxwell (1864)
- predicted that an alternating current in a circuit would radiate energy in the form of ELECTROMAGNETIC waves travelling through vacuum at the speed of light
> Heinrich Hertz
- did a demo thru an experiment 'the electromagnetic nature of light' to confirm Maxwell's interpretation
Classical Idea:
I. light is a WAVE
nature of light
II. Quantum Nature of Light
Max Planck (1858-1947)
- radiation energy is not continuous
- occurs in PACKETS or PIECES
PACKETS - Quanta
PIECES - Quanta
Quanta Hypothesis:
- thought light was a particle
Photon - quantum of electromagnetic radiation
( the higher the energy the shorter the wave :D)
Albert Einstein
- applied the photon model of light to explain the PHOTOELECTRIC EFFECT
- won the Nobel Prize for PHYSICS
DUALISM in Nature
behaviour of Light
1. Wave
2. Particle
each can explain one set of phenomena but is in compatible w/ the other set.
Louis de Broglie (1892-1987)
- proposed a dualistic nature of light to explain its behaviour
- to there is a relationship between frequency & energy of photons w/ the wave nature of radiations
- correlate the motion of each particle to a certain wave characterizes its wave properties
- won him a Nobel Prize
BOHR
- combined Rutherford's nuclear atom, Planck's quantum nature, Maxwell's wave model & Newton's Lay of motion
- formed 4 postulates
Postulates:
1. A hydrogen atom consists of a nucleus containing a proton & an electron
2. Only certain orbits are permitted
3. Energy of the e- in a given orbit is fined. As long as the electron stays in that orbit, it neither absorbs nor radiates energy. (stationary state/ground)
4. Electron may move from one stationary state to another (excited state x 3) to do so, it must absorb or emit a quantity of energy
Energy Levels in an Atom
Bohr proposed the energy levels based from the idea of Bohr who proposed that the movement of e- is analogous to the planets orbiting around the sun.
- orbits-> energy level
MAIN ENERGY LEVEL/SHELL
-> the orbits where the e-'s are located
n= 1,2,3,4,etc...
-> compared to a building, the nucleus being the basement and the high levels are the different shells :D
-> each level being greater than the previous
SUBSHELL/SUBLEVEL (s,p,d,f)
-> although a number of e-s may be found in the same main energy level, they may be found in different sublevels
Main Energy Level 1 is found in Subshell type 1s
MEL = 2 : ST = 2s,2p
MEL = 3 : ST = 3s, 3p, 3d
MEL = 4 : ST = 4s, 4p, 4d, 4f
ENERGY LEVELS IN AN ATOM
# of sublevels = assigned nos. for the main energy level
ORBITALS
-> region around the nucleus in which e-s will most likely be found
- rooms for electrons
- 1 orbital can only accommodate a max. number of 2 electrons
max. # of e-'s that can = 2n^2
occupy a level/shell
h=main energy level
How many electrons can occupy the 9th Main energy level?
2n^2 = 2(9)^2 = 2(81) = 162 electrons can occupy the 9th Main energy level
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JULY 24
PICTURING THE ELECTRON
- ground state configuration
(How electrons arrange/themselves in atoms)
WAY TO DESCRIBE THE ELECTRON DISTRIBUTION :D
1. Orbital Energy Diagram (OED)
2. Orbital Diagram Notation (ODN)
3. Electron Configuration (EC)
4. Nobel Gas Abbreviation
5. Shell Configuration
~~~~~****~~~~~
1. OED
-uses boxes and arrows and breaks down each subshell into individual ORBITALS and ENERGY
3 PRINCIPLES in filling up the ORBITALS
* Aufbau Principle*
- electrons are added one at a time starting at the orbital w/ the LOWEST energy (1s)
*Pauli's Exclusion Principle
- an orbital can hold a maximum of 2 electrons...
The up arrow represents the direction: clockwise; the down arrow is counter clockwise.
*Hund's Rule of Multiplicity
- electrons entering a sublevel containing more than one orbital will be spread out with their spins in the SAME direction so that electrons are distributed singly before they are paired.
Practice :)
show the orbital energy of diagram of F(z=9)
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2. ODN
- uses boxes & arrows and breaks down each subshell into ORBITALS
- similar to OED except that the direction of increasing energy is from left to right
ex.
show the orbital diagram of NA (z=11)
Practice
He (z=2)
P(z=15)
O(z=8)
Cl(z=17)
N (z=7)
F(z=9)
S(z=16)
Rb(z=37)
~~~~~****~~~~~
3. EC
- uses letters and nos. & denotes only the TOTAL nos. of electrons in each subshell
2p^3
2 - principle energy level
p - represents the sublevel
3 - total nos. of electrons in sublevel
ex. Write the electron configuration of Na (z=11)
White the full EC of each of the ff:
He(z=2)
S(z=16)
P(z=15)
N(z=7)
O(z=8)
Cl(z=17)
~~~~~****~~~~~
Cr (z=24)
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^4
4s^2 -> 4s^1
3d^4 -> 3d^5
Cu (z=29)
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^9
4s^2 -> 4s^1
3d^9 -> 3d^10
REASON
STABILITY:
Filled Orbital > Half-filled Orbital > Partially filled Orbital
Types of Electrons
1. Valence electrons (v.e.)
- e-'s in the outermost principal energy level/shell
- ones involved in the chemical reactions
2. CORe elctrons (c. e.)
- e-'s that don't participate in chemical reactions
Noble Gas Abbreviation
- shortcut way of writing....
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