Atomic Structure
Miha Lee
California State University,
Northridge
List of Content
Particles in a Atom
• Nucelus => Neutrons & Protons
• Electrons
2. Atomic Structure
• Bohr => energy level of electron shell
• Shrodinger => orbitals & electron cloud
3. Electron Configuration
• Rule of Elctronic Configuration
• Atoms’ Electronic Configuration
• Links for Self-study
1.
Electron
 J.J. Thomson
 Cathode-ray
 The atom has a lot of tiny,
negatively charged particles
named electrons stuck in it.
Nucelus 1
 Rutherford
 α particle scattering
Nucelus 2
 The atom has a small,
dense, positively
charged nucleus and
electrons at a distance.
 The vast majority of
the volume of the atom
is empty space.
Particles in Nucleus
 Proton
 1.602×10−19 C
 1.673×10−27 kg
 Neutron
 no net charge
 1.675×10−27 kg
Atomic Structure
Bohr => elenergy level of
electron shells
Schrodinger => orbitals &
electron cloud
Bohr’s Atomic Model 1
 Cause: Line spectrum of atoms =>
discrete energy levels in an atom
Bohr’s Atomic Model 2
 Borh’s idea about
Line spectrum
 Electrons orbit
around the nucleus
in discret allowed
energy levels
(electron shells).
 Electrons gain and
lose energy by
jumping from one
orbit to another.
Atomic Orbitals 1
 Schrodinger
 Electrons’ motion is
described as wavefunction.
 Probaility of finding
electrons is caculated
from wave function
and named orbital.
Atomic Orbitals 2
 Watch wave
functions and
orbitals
 Elctron cloud:
probaility of finding
electron (orbital)
decribed with dots
Atomoic Orbitals 3
 Orbitals: area of 90~95% of probaility
to find electrons
s orbital
p orbials
d orbitals
Electronic Configuration 1
 Each orbital can only
contain a maximum of
2 electrons.
 Elctron shells at a
higher energy level
have more orbitals.
 Order of filling energy
levels => 1s2 2s2 2p6
3s2 3p6 4s2 3d10 4p6
Rule of Elctronic Configuration
 The Aufbau Principle
 The electrons occupy the lowest energy orbitals available.
The “Ground State” for an atom is when every electron is
in its lowest energy orbital.
 The Pauli Exclusion Principle
 Each orbital can be occupied by no more than two
electrons.
 Hund’s Rule
 When more than one orbital exists of the same energy (p, d,
and f orbitals), place one electron in each orbital
Atoms’ Electronic Configuration
Links for Electronic Configuration
 Electronic Structures
 Electron Configuration
 Atomic electron configurations
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