Agenda Midterm – October 26 th / 27th Chapter 5 Quiz – October 21 Formal Lab – October 21 st Homework (wb 5) – October 24/25th

Agenda

Midterm – October 26th / 27thChapter 5 Quiz – October 21

Formal Lab – October 21st

Homework (wb 5) – October 24/25th

Light• Electromagnetic radiation– Form of energy that exhibits wavelike behavior

Terms to know– Wavelength• Measured from crest to crest (measured in meters, m)

– Amplitude• A waves height

– Frequency• Number of waves that pass a given point

Low frequency

High frequency

The speed of Light

C is a given = 3.00 x 108 m/sλ = wavelength (meters, m)ν = frequency (Herts, Hz = waves per second)

Answer the following questions pg 121• What is the frequency of a green light, which has a

wavelength of 4.90 x 10 -7m?• An X ray has a wavelength of 1.15 x 10 -10m?• What is the speed of an electromagnetic wave that

has a frequency of 7.8 x 10 -6 Hz• A popular radio station broadcast with a frequency

of 94.7 MHz What is the wavelength of the broadcast? (1MHz = 10 6 Hz)

Particle nature of Light• Quantum = minimum amount of energy that can

be gained or lost by an atom• The energy of a quantum is related to the

frequency of the emitted radiation

Planck’s Constant

• Equantum = hν– H = 6.626 x 10 -34 J(s)– ν = frequency measure per second

Answer the following Question pg 124• What is the energy of each of the following types

of radiation?– A 6.32 x 1020 s-1

– b. 9.50 x 1013 Hz– c. 1.05 x 10 16 s-1

• Answer the questions on page 147 #s 65-76

N - 1

N - 5N - 4

N - 2 N - 3

N - 5

Bohr Model of the Atom• A single electron moves around the nucleus in

only certain allowed circular orbits.• Each orbit has an energy level– Larger the orbit…larger the energy level

• “n” = the quantum number– This the orbit and the corresponding energy level.

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Bohr’s Model of the atom

The larger the orbital, the further the e- are from the nucleus

+

n = 1

n = 2

n = 3n = 4

Quantum # (n)- Indicated energy level or orbital

The probability of finding e- in certain regions of an atom is described by an orbital

Orbitals have characteristic shapes, size and energies, but do NOT tell how e- move

Neils Bohr

Energy LevelsN-1• S orbital only…2 electronsN-2• S orbital…P orbital…6 electronsN-3• S & P orbitalN-4• S…3d orbital (10 electrons)…P N-5• S…4d orbital (10 electrons)…P N-6• S…5d orbital (10 electrons)…4f orbital (14 electrons)…P N-7• S…6d orbital (10 electrons)…5f orbital (14 electrons)…P

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Quantum model

• Each Orbital has energy levels

Ground State Electron Configurations

• Aufbau principle…each electron occupies the lowest energy orbital available.

• Pauli exclusion principle– 2 electrons occupy a single orbital– Each electron has an opposite spin

• Hund’s rule– Single electrons with the same spin must occupy each

equal energy orbital before additional electrons with opposite spins can occupy the same orbitals. Pg 136

Aufbau Principle

• Each electron occupies the lowest energy orbital available

Pauli’s Exclusion Principle

Pauli’s Exclusion Principle

Hund’s Rule

• Single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy same orbitals

Hund’s Rule

The Orbitals

Orbital diagrams

Noble Gas Notation

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Electron Spin- e- spin either clockwise or counterclockwise which creates a magnetic field

Pauli Exclusion Principle –

- an orbital with 2e- of opposite spin are said to have a pair of e-

Sublevels # Orbitals Max # of e- s 1 2 p 3 6 d 5 10 f 7 14

Figure 4-24

each orbital in an atom can hold up to 2e- that must have opposite spin ( and )

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Electron ConfigurationsDefinition

Distribution of e- among orbitals; describes where e- are and what energy they have

Aufbau Principle –

Hund Rule –

_____ _____ _____ _____ _____ 1s 2s 2px 2py 2pz 1s2 2s2 2p6

e- are added one at a time to the lowest energy level available

e- occupy equal energy orbitals so the maximum number of unpaired e- result

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• 1s2 2s2 2p6

•

• Orbital Last level of energy

• Number of electrons in a particular orbital

Level of energy

This particular atoms has2 levels of energy 10 electron total 2 + 2 +68 electrons in the last level of energy 2 +6

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How To Do Energy Diagrams

Step 1

Step 2

Step 3

Step 4

Determine atomic number

Determine number of e-- if neutral: # e- = atomic #- if ion: # e- = atomic # - charge

Fill in atomic orbital energy diagram using following principles- Pauli: 2e- max per orbital with opposite spin- Aufbau: 1e- at a time filling lowest energy levels first- Hund: max # of unpaired e-

Determine number of paired and unpaired e-

Step 5 Write e- configuration

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Example Determine the e- configuration of Ne by using an atomic orbital energy diagram

3s _____2p _____ _____ _____

2s _____1s _____

Atomic # = 10# e- = 10 – 0 = 10

Paired = 5Unpaired = 0

e- config: 1s22s22p6

Example Determine the e- configuration of S by using an atomic orbital energy diagram

4s _____3p _____ _____ _____

3s _____2p _____ _____ _____

2s _____1s _____

Atomic # = 16# e- = 16 – 0 = 16

Paired = 7Unpaired = 2

e- config: 1s22s22p63s23p4

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Example Determine the e- configuration of Fe+ by using an atomic orbital energy diagram

3d _____ _____ _____ _____ _____4s _____

3p _____ _____ _____ 3s _____

2p _____ _____ _____2s _____1s _____

Atomic # = 26# e- = 26 – 1 = 25

Paired = 10 Unpaired = 5

e- config: 1s22s22p63s23p64s23d5

Example Determine the e- configuration of F- by using an atomic orbital energy diagram

3s _____2p _____ _____ _____

2s _____1s _____

Atomic # = 9# e- = 9 – -1 = 10

Paired = 5 Unpaired = 0

e- config: 1s22s22p6

36Start with 1s and read up the arrow

Order of Energy Levels from Lowest (1s) to Highest

Group 1 – Alkali Metals

Group 2 – Alkaline Earth Metals

Group 1- 10 – Transition Metals

Group 5 – Nitrogen Group

Group 8 – Nobel Gas

Group 3 – Boron GroupGroup 4 – Carbon Group

Group 6 – Oxygen GroupGroup 7 – Halogens

Period 4f– LanthanidesPeriod 5f– Actinides

Valence Electrons

• Only certain electrons can determine the chemical properties of an element– Valence Electrons

• Valence electrons are defined as electron’s in the atom’s outermost orbital…or highest energy level

Valence Electrons

• Steps to create Lewis Structures for single elements– Find the number of electrons in the last S and P

orbitals…or look on the chart to find the number of valence electrons on the periodic table

– Arrange electrons around Element symbol evenly– Ex: Chlorine• 7 Valence Electrons

Cl

Valence Electrons

Valence Electrons• Electrons in the atom’s most outer orbitals– The electrons in the last S and P orbitals

Boron – 1s2 2s2 2p1

Iodine– 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p5

Electron Dot…

• H C O He

• Li P F Ar