Chemistry Chapter 4
Arrangement of Electrons in Atoms

electromagnetic radiation- a form of energy
that exhibits wavelike behavior as it travel
through space
– wavelength ( λ )- the distance between
corresponding points on adjacent waves
– frequency ( f ) the number of waves that pass
through a specific point in a specific time
– hertz ( Hz )- a frequency of one wave per second
Speed of Electromagnetic Radiation

The speed ( c ) of all wavelengths of
electromagnetic radiation = 3.0 x 108 m/s.
c = fλ
IF “c” is a constant, then wavelength
varies inversely with the frequency of
electromagnetic radiation.
Photoelectric Effect

photoelectric effect- the emission of

quantum- the minimum amount of energy that
electrons from a metal when light shines on that
metal
can be gained or lost by an atom
– photon- a quantum of light energy
– ground state- the lowest energy state of an atom
– excited state- a higher energy state
Spectra

line-emission spectrum- The specific colors
(frequencies) of light emitted when an atom
returns to the ground state from the excited
state.
 It can be seen when the light is separated by a prism and
will give an element a specific spectrum.

continuous spectrum- the emission of a
continuous range of frequencies of
electromagnetic radiation
Section 2
The Quantum Model of the Atom

Heisenberg Uncertainty Principle- it is

Quantum theory- describes mathematically

orbital- a three-dimensional region around the
impossible to determine simultaneously both the
position and the velocity of an electron
the wave properties of electrons
nucleus that indicates the probable location of
an electron
– Each orbital can contain a maximum of 2 electrons.
Atomic Orbitals and Quantum
Numbers

quantum numbers- specify the properties of atomic
orbitals and the properties of the electrons in the orbitals
– principal quantum number- indicates the main energy level
occupied by an electron
 the number of electrons possible per energy level = 2 n2 where
n = energy level
– angular momentum quantum number- indicates the shape
of an orbital
 s, p, d, & f
– magnetic quantum number- indicates the orientation of an
orbital around the nucleus of an atom
– spin quantum number- indicates the two fundamental states
of spin of an electron
Orbitals

There is a single “s” orbital per energy level for a
maximum of 2 “s” electrons per level.
– the energy level for “s” orbitals = the period number

There are 3 “p” orbitals per energy level for a maximum
of 6 “p” electrons per level.
– the energy level for “p” orbitals = the period number

There are 5 “d” orbitals per energy level for a maximum
of 10 “d” electrons per level.
– the energy level for “d” orbitals is the period number minus 1

There are 7 “f” orbitals per energy level for a maximum
of 14 “f” electrons per level.
– the energy level for “f” orbitals is the period number minus 2
Section 3
Electron Configurations

electron configuration- the arrangement of

Rules governing electron configuration:
electrons in an atom
– Aufbau principle- an electron occupies the lowest
energy orbital that can receive it
– Pauli exclusion principle- no two electrons in the
same atom can have the same four quantum
numbers
– Hund’s rule- orbitals of equal energy are each
occupied by one electron before any orbital is
occupied by a second electron
Electron Configuration Notation

ORBITAL NOTATION: See pg 112-113.

ELECTRON-CONFIGURATION NOTATION:
See pg 113
[Ne] 3s23p4
Do Practice #1 & #2 on page 113.
Elements & Electron Configurations
 1st
period elements- see periodic table
 2nd period elements
 3rd period elements
– noble-gas configuration- refers to an
outer main energy level occupied by eight
electrons ( ns2np6 in most cases)
 4th
period elements
 5th period elements
– Do Practice #1-4 on page 121.
Elements & Electron Configurations

Elements of the 6th and 7th periods contain “f”
orbitals.
– Do Practice #1 & 2 on page 122.
– Do Section Review #5 on page 122.
– Do Chapter review #33, 36, & 38 on pages 125-126.
– Review for Chapter 4 Test
Chapter 4 Test(40 questions)
Know the meaning of the formula c = fλ .
Know the meaning of hertz, wavelength, photon,
photoelectric effect, ground state, excited state.
 Know how EMR travels through space.
 Know how a line spectrum is produced.
 Know what must happen for an electron to move
between the ground and excited states.
 Understand the Bohr model of atoms.
 Know the definition of electron cloud, the quantum
numbers, orbital.
 Know how to calculate number of electrons per energy
level.


Chapter 4 Test
Understand the differences in the energies of different
orbital sublevels.
 Know Aufbau principle, Hund’s rule, & Pauli exclusion
principle.
 Identify elements using their electron configuration
notation.
 Determine the electron configuration notation of
elements.
 Know the definition of a noble gas.
 Write an electron configuration notation using an
element’s orbital notation.
 Identify an element using its orbital notation diagram.
