Chemistry Chapter 4Chemistry Chapter 4Arrangement of Electrons in Arrangement of Electrons in

AtomsAtoms electromagnetic radiation-electromagnetic radiation- a form of a form of

energy that exhibits wavelike behavior as energy that exhibits wavelike behavior as it travel through spaceit travel through space

– wavelength ( wavelength ( λλ ) )-- the distance between the distance between corresponding points on adjacent wavescorresponding points on adjacent waves

– frequency ( f )frequency ( f ) the number of waves that the number of waves that pass through a specific point in a specific timepass through a specific point in a specific time

– hertz ( Hz )-hertz ( Hz )- a frequency of one wave per second a frequency of one wave per second

Speed of Electromagnetic Speed of Electromagnetic RadiationRadiation

The speed ( c ) of The speed ( c ) of allall wavelengths of wavelengths of electromagnetic radiation = 3.0 x 10electromagnetic radiation = 3.0 x 1088 m/s.m/s.

c = fc = fλλ

IF “c” is a constant, then wavelength IF “c” is a constant, then wavelength varies inversely with the frequency of varies inversely with the frequency of electromagnetic radiation. electromagnetic radiation.

Photoelectric EffectPhotoelectric Effect photoelectric effect-photoelectric effect- the emission of the emission of

electrons from a metal when light shines on electrons from a metal when light shines on that metalthat metal

quantum-quantum- the minimum amount of energy the minimum amount of energy that can be gained or lost by an atomthat can be gained or lost by an atom

– photon-photon- a quantum of light energy a quantum of light energy– ground state-ground state- the lowest energy state of an the lowest energy state of an

atomatom– excited state-excited state- a higher energy state a higher energy state

SpectraSpectra

line-emission spectrum-line-emission spectrum- The specific The specific colors (frequencies) of light emitted when colors (frequencies) of light emitted when an atom returns to the ground state from an atom returns to the ground state from the excited state. the excited state.

It can be seen when the light is separated by a prism It can be seen when the light is separated by a prism and will give an element a specific spectrum.and will give an element a specific spectrum.

continuous spectrum-continuous spectrum- the emission of a the emission of a continuous range of frequencies of continuous range of frequencies of electromagnetic radiationelectromagnetic radiation

Section 2Section 2The Quantum Model of the The Quantum Model of the

AtomAtom Heisenberg Uncertainty Principle-Heisenberg Uncertainty Principle- it is it is

impossible to determine simultaneously both impossible to determine simultaneously both the position and the velocity of an electronthe position and the velocity of an electron

Quantum theory-Quantum theory- describes describes mathematically the wave properties of mathematically the wave properties of electronselectrons

orbital-orbital- a three-dimensional region around a three-dimensional region around the nucleus that indicates the probable the nucleus that indicates the probable location of an electron location of an electron – Each orbital can contain a Each orbital can contain a maximummaximum of 2 of 2

electrons. electrons.

Atomic Orbitals and Quantum Atomic Orbitals and Quantum NumbersNumbers

quantum numbers-quantum numbers- specify the properties of specify the properties of atomic orbitals and the properties of the electrons atomic orbitals and the properties of the electrons in the orbitalsin the orbitals– principal quantum number-principal quantum number- indicates the main indicates the main

energy level occupied by an electronenergy level occupied by an electron the number of electrons possible per energy level = 2 nthe number of electrons possible per energy level = 2 n22

where where n = energy leveln = energy level– angular momentum quantum number-angular momentum quantum number- indicates the indicates the

shape of an orbitalshape of an orbital s, p, d, & fs, p, d, & f

– magnetic quantum number-magnetic quantum number- indicates the orientation indicates the orientation of an orbital around the nucleus of an atomof an orbital around the nucleus of an atom

– spin quantum number-spin quantum number- indicates the two fundamental indicates the two fundamental states of spin of an electronstates of spin of an electron

OrbitalsOrbitals There is a single “s” orbital per energy level for a There is a single “s” orbital per energy level for a

maximum of 2 “s” electrons per level.maximum of 2 “s” electrons per level.– the energy level for “s” orbitals = the period numberthe energy level for “s” orbitals = the period number

There are 3 “p” orbitals per energy level for a There are 3 “p” orbitals per energy level for a maximum of 6 “p” electrons per level.maximum of 6 “p” electrons per level.– the energy level for “p” orbitals = the period numberthe energy level for “p” orbitals = the period number

There are 5 “d” orbitals per energy level for a There are 5 “d” orbitals per energy level for a maximum of 10 “d” electrons per level.maximum of 10 “d” electrons per level.– the energy level for “d” orbitals is the period number the energy level for “d” orbitals is the period number

minus 1minus 1 There are 7 “f” orbitals per energy level for a There are 7 “f” orbitals per energy level for a

maximum of 14 “f” electrons per level.maximum of 14 “f” electrons per level.– the energy level for “f” orbitals is the period number minus the energy level for “f” orbitals is the period number minus

22

Section 3Section 3Electron ConfigurationsElectron Configurations

electron configuration-electron configuration- the the arrangement of electrons in an atomarrangement of electrons in an atom

Rules governing electron Rules governing electron configuration:configuration:– Aufbau principle-Aufbau principle- an electron occupies the an electron occupies the

lowest energy orbital that can receive itlowest energy orbital that can receive it– Pauli exclusion principle-Pauli exclusion principle- no two electrons no two electrons

in the same atom can have the same four in the same atom can have the same four quantum numbersquantum numbers

– Hund’s rule-Hund’s rule- orbitals of equal energy are orbitals of equal energy are each occupied by one electron before any each occupied by one electron before any orbital is occupied by a second electronorbital is occupied by a second electron

Electron Configuration Electron Configuration NotationNotation

ORBITAL NOTATION: See pg 112-113.ORBITAL NOTATION: See pg 112-113.

ELECTRON-CONFIGURATION NOTATION:ELECTRON-CONFIGURATION NOTATION:See pg 113See pg 113

[Ne] 3s[Ne] 3s223p3p44

Do Practice #1 & #2 on page 113.Do Practice #1 & #2 on page 113.

Elements & Electron Elements & Electron ConfigurationsConfigurations

11stst period elements- see periodic table period elements- see periodic table 22ndnd period elements period elements 33rdrd period elements period elements

– noble-gas configuration-noble-gas configuration- refers to an refers to an outer main energy level occupied by eight outer main energy level occupied by eight electrons ( nselectrons ( ns22npnp66 in most cases) in most cases)

44thth period elements period elements 55thth period elements period elements

– Do Practice #1-4 on page 121.Do Practice #1-4 on page 121.

Elements & Electron Elements & Electron ConfigurationsConfigurations

Elements of the 6Elements of the 6thth and 7 and 7thth periods contain periods contain “f” orbitals.“f” orbitals.

– Do Practice #1 & 2 on page 122.Do Practice #1 & 2 on page 122.

– Do Section Review #5 on page 122.Do Section Review #5 on page 122.

– Do Chapter review #33, 36, & 38 on pages Do Chapter review #33, 36, & 38 on pages 125-126.125-126.

– Review for Chapter 4 TestReview for Chapter 4 Test

Chapter 4 Test-Chapter 4 Test-(40 questions)(40 questions)

Know the meaning of the formula Know the meaning of the formula c = fc = fλλ . . Know the meaning of hertz, wavelength, photon, Know the meaning of hertz, wavelength, photon,

photoelectric effect, ground state, excited state.photoelectric effect, ground state, excited state. Know how EMR travels through space.Know how EMR travels through space. Know how a line spectrum is produced.Know how a line spectrum is produced. Know what must happen for an electron to move Know what must happen for an electron to move

between the ground and excited states.between the ground and excited states. Understand the Bohr model of atoms.Understand the Bohr model of atoms. Know the definition of electron cloud, the Know the definition of electron cloud, the

quantum numbers, orbital.quantum numbers, orbital. Know how to calculate number of electrons per Know how to calculate number of electrons per

energy level.energy level.

Chapter 4 TestChapter 4 Test Understand the differences in the energies of Understand the differences in the energies of

different orbital sublevels.different orbital sublevels. Know Aufbau principle, Hund’s rule, & Pauli Know Aufbau principle, Hund’s rule, & Pauli

exclusion principle.exclusion principle. Identify elements using their electron configuration Identify elements using their electron configuration

notation.notation. Determine the electron configuration notation of Determine the electron configuration notation of

elements.elements. Know the definition of a noble gas.Know the definition of a noble gas. Write an electron configuration notation using an Write an electron configuration notation using an

element’s orbital notation.element’s orbital notation. Identify an element using its orbital notation Identify an element using its orbital notation

diagram.diagram.