Atomic Structure

Miha LeeCalifornia State University,

Northridge

List of Content

1. 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

Electron

J.J. Thomson Cathode-ray

The atom has a lot of tiny, negatively charged particles named elec-trons stuck in it.

Nucelus 1Rutherford α particle scatter-

ing

Nucelus 2The atom has a

small, dense, posi-tively charged nu-cleus and electrons at a distance.

The vast majority of the volume of the atom is empty space.

Particles in Nucleus

Proton1.602×10−19 C1.673×10−27 kg

Neutronno net charge1.675×10−27 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 wave-function.

Probaility of finding electrons is caculated from wave function and named orbital.

Atomic Orbitals 2

Watch wave functions and orbitals

Elctron cloud: probaility of find-ing electron (or-bital) 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 maxi-mum 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 Configura-tion

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 en-

ergy (p, d, and f orbitals), place one electron in each orbital

Atoms’ Electronic Configura-tion

Links for Electronic Configura-tion

Electronic Structures Electron Configuration Atomic electron configurations

[end]