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Electronic Structure of Atom (Electromagnetic wave (Visible light…
Electronic Structure of Atom
Atomic History
DEMOCRITUS (Atomos)
The matter is comprised of fundamental indivisible which called atomos
JOHN DALTON
(Compound Consist different
types of Atom in a whole number ratio)
Provided the first empirical evidence the atoms exist
Chemical reaction involves the rearrangement of those atoms to give new combination
Example : water
J.J Thamson (Electron)
The atom must consist of smaller particles
Example : Cathode Ray
ERNEST RUTHERFORD
Gold Foil Experiment
Positive charged alpha particle are very tiny which a thin foil of gold
quantum no
n=principle quantum no
= the shell or energy level in which an electron resides
l = azimuthal quantum no
= specifies a subshell in an atom
0=s 1= p 2 = d 3=f 4=good
m1=magnetic quantum no
= orientation of orbital relative to each other
Values : -1, 0, +1
ms= spin quantum no
= the direction of the electron to spin on its axis
Values : ms =+1/2 ( an e- spinning in clockwise direction)
ms=-1/2 ( an e- spinning in anticlockwise direction) * only 2 e-book occupy each orbital
electrons must hv opposite spins
Electromagnetic wave
Visible light separates into a continuous spectrum of colors when passes through a prism.
Visible lights are red, orange, yellow, green, blue and violet in colour.
Visible light exist at wavelengths ranging from 400-750 nm.
Electromagnetic radiation travel in waves and are defined by their wavelength and frequency.
c = λ v
c is the speed of light
λ is wavelength
v is frequency
Invisible light consists of gamma-rays, X-rays, ultra-violet, Infra-red and microwave
Electron excitation and spectra.
ΔE=hv
Modern Atomic Model
Quantum Atomic Model
Different levels indicates different shapes and number of orbital
s orbital
spherical shaped
maximum 1 in one energy level
maximum contain 1 electron pair with opposite spins
p orbital
Dumb-bell shaped
Maximum 3 in one energy level
3 orbitals orientate on x, y and z-axis
d orbital
Four-lobe shaped
Maximum 5 in one orbital
f orbital
Six-lobe shaped
Maxium 7 in one orbitals
Proposed by Erwin Schrodinger
Louis de Broglie (1924)
suggested that
electron could act as particle and wave
, as light may act as wave or particle
Werner Heisenberg
disagreed about it and suggest the
uncertainty principle
combined de Broglie's hypothesis and Heisenberg's uncertainty principle
defined electron cloud as specific region in which large probability of finding electrons (High electron density)
divided into 4 types of quantum number
Principal quantum number (n) - describes the energy level of an electron.
Azimuthal quantum number (l) - describes the speed of electron during its angular momentum.
Magbetic quantum number (ml) - electrons orientation in space
Spin quantum number (ms) - direction that electron spinswhile moving in orbit