Electron Properties and ArrangementChapter 5

Objectives:

• Identify the properties of electrons.

• Understand how electrons move in atoms.

• Distinguish between atoms based on their different electron arrangements. .

Electrons in AtomsElectrons in Atoms• What do you know about electrons in atoms?

• Using Bohr’s model illustrate and label the sub-particles in the following neutral atoms:

a. H-1 b. C-12 c. Ne-20

Electrons and Light ParticlesElectrons and Light Particles

Similarities:

• Very tiny particles

• Extremely small masses

• Move at very high speeds (3.0x108 m/s)

Electromagnetic Radiation SpectrumElectromagnetic Radiation Spectrum•Electromagnetic Spectrum : Divides light particles into regions based on their wave-like properties.

a. Relationship b/w wavelength and frequency?b.Relationship b/w wavelength and energy emission?c.Relationship b/w frequency and energy emission?

Wave-Like Properties: WavelengthWave-Like Properties: Wavelength• Wavelength: length of wave from two neighboring crest.

• Amplitude: height of wave from origin to crest.

Wave-Like Properties: FrequencyWave-Like Properties: FrequencyFrequency (Hz) : how many waves pass a certain point per second. Units: Hz (waves/second)

Wave-Like Properties: EnergyWave-Like Properties: Energy• Temperature = energy emitted by light

particles.

• Photons = light particles that are classified by the amount of energy they emit off.

Electromagnetic Spectrum AnalysisElectromagnetic Spectrum Analysis

• 1

What light particle region has the longest wavelength?What light particle region has the lowest frequency?What light particle region emits the highest amount of energy?As wavelength decreases for a light particle, what happens to frequency? Sketch a line graph illustrating the relationship between wavelength and frequency.As frequency increases for a light particle what happens to it its energy?Sketch a line graph illustrating the relationship between frequency and energy. In the visible region, (ROYGBIV), does red or violet light particles have a slightly smallerwavelength?

Electromagnetic Spectrum ApplicationsElectromagnetic Spectrum Applications•“Electromagnetic Spectrum Song” by Emerson and Wong Yann

Electromagnetic Radiation SpectrumElectromagnetic Radiation Spectrum

a. Relationship b/w wavelength and frequency?b.Relationship b/w wavelength and energy emission?c.Relationship b/w frequency and energy emission?

Visible Region: Continuous Spectrum

Continuous Spectrum = Presence of all light particles in the visible region.

Visible Region: Absorption SpectrumAbsorption Spectrum = Presence of dark bands

that indicate light particles absorbed by matter.

• At room temperature we observe light particles reflected.by matter.

An Atom’s Interaction with Light ParticlesAn Atom’s Interaction with Light Particles

Light Particles

Atom

Atoms Interaction with Light ParticlesAtoms Interaction with Light Particles

Light Particles

Atom

Electrons absorb light particles

•Electrons absorb specific light particles or photons.•Electrons that absorb photons can move to higher energy levels.

Electron MovementElectron Movement

1. Ground state of H Atom (lowest energy level for e-)2. A photon (light particle) is absorbed by H’s electron. Electron becomes excited and jumps to higher energy level.3. E- returns to ground state and emits (releases) the photon.

Emitted photon’s wavelength can be detected by scientists. (Infrared region at room temp; Visble region at higher temps.)

1. 2. 3.

Electron MovementElectron Movement

1. 2. 3.

Flame Test LabFlame Test LabPurpose:

• Heat matter (atoms) so that we can observe the emission of photons from electrons.

Flame Test LabFlame Test LabPurpose:

• Heat matter (atoms) so that we can observe the emission of photons from electrons.

Conclusions:

• Electron movement occurs instantaneously.

• Elements’ electrons emit off different photons of energy and color.

• Identify elements by the distinct color (photons) they emit off.

Bell Ringer: Electron MovementBell Ringer: Electron Movement1. Illustrate and explain the movement of electrons in an

atom using the following terms:

(photons, absorption, emission, energy levels, ground state, and excited state)

2. Rank the samples’ color based on the following:

a. Increasing wavelength.

b. Decreasing frequency.

c. Increasing emission of energy.

3. Which sample do you predict had electrons that moved the farthest during the flame test lab.

4. Explain how the flame test lab would be beneficial for forensic scientists.

Bell Ringer: Electron MovementBell Ringer: Electron Movement2. Rank the samples’ color based on the following:

a. Increasing wavelength. (data table)

*b. Decreasing frequency. (electromagnetic spectrum)

*c. Increasing emission of energy. (electromagnetic spectrum)

Visible Region of EM Spectrum

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Electromagnetic Radiation SpectrumElectromagnetic Radiation Spectrum

a. Relationship b/w wavelength and frequency?b.Relationship b/w wavelength and energy emission?c.Relationship b/w frequency and energy emission?

Bohr’s Model of the AtomBohr’s Model of the Atom

• The electron cloud consists of energy levels.

• Electrons reside and move around in these energy levels.

• Electrons can move to other energy levels when absorb photons.

Electron MovementElectron Movement

1. Ground state of H Atom (lowest energy level for e-)2. A photon (light particle) is absorbed by H’s electron. Electron becomes excited and jumps to higher energy level.3. E- returns to ground state and emits (releases) the photon.

Emitted photon’s wavelength can be detected by scientists. (Infrared region at room temp; Visble region at higher temps.)

1. 2. 3.

Infinite Campus UpdateInfinite Campus Update

• Flame Test Lab

*Quiz tomorrow over electron properties, wave-like properties, and electron movement.

Electron MovementElectron Movement

1. Explain the difference between the ground state and the excited state of an electron in an atom.

2. In the flame test lab, the color change occurred when electrons ________ photons and dropped down to an energy level closer to the nucleus.

(absorbed, reflected, emitted)

Continuous Spectrum ReviewContinuous Spectrum = Reflection of all light

particles by electrons in the visible region.

Ex. sun; white light bulbs

Visible Region Absorption Spectrum

Absorption Spectrum = Reveals what light particles are reflected and absorbed by electrons.

Emission Spectrum Emission Spectrum =Reveals what photons are

emitted during electron movement.

Ex. Hydrogen Light

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Emission Spectrums

•Emission spectrum for each element is unique.

Emission Spectrums

•Emission spectrum for each element is unique.

Electron Movement in Energy LevelsElectron Movement in Energy Levels

•Quantum of energy: •Specific energy that is absorbed or emitted by electrons.• Energy difference between two energy levels. •Scientist can calculate energy emitted by electrons.•Determine what energy levels electrons move between in an atom.

Locating an ElectronLocating an Electron• Is it possible to know the exact location and velocity of an electron at any instant

in time?

• Very difficult to locate an electron because:

- moving extremely fast

-continuously bombarded by light particles

• When locate an electron with a photon from a microscope, it changes its velocity in unpredictable ways.

Photon

Before

Photon changes wavelength

After

Heisenberg Uncertainty Principle

It is not possible to know the exact position and velocity of an electron at the same time.

Electron Movement and ArrangementElectron Movement and Arrangement

1. What principle states that you cannot know the location and velocity of an electron at the same time?

2. Why is an emission spectrum unique for each element?

3. What is quantum energy?

Electron Movement and ArrangementElectron Movement and Arrangement

1. What principle states that you cannot know the location and velocity of an electron at the same time?

2. Why is an emission spectrum unique for each element?

3. What is quantum energy?

4. What is the quantum mechanical model?

5. What is the maximum number of electrons on the 5th energy level?

The Quantum Mechanical ModelThe Quantum Mechanical Model• An atomic model that best explains the probable

arrangement and movement of electrons at any moment in time.

• Schrodinger provided evidence for this model usinga complex mathematical equation.

• Depends upon 4 quantum numbers. Erwin Schrodinger

n-Quantum Numbern-Quantum Number n = energy levels

• 3-D region of space around the nucleus where an electron can be found.

• Each energy level has a specific energy value.

• E- must absorb or release a specific quantum of energy to move between energy levels.

• E- do not travel in an orbit (exact path) around the nucleus.

Atomic orbitals: Probable paths an electron would take around the nucleus.

Energy Levels and the Periodic TableAssociate energy levels with rows on periodic table.

n-Quantum Numbern-Quantum Number

• Limited number of electrons on each energy level.

• 2n2 Rule determines the maximum number of electrons on each energy level.

l–Quantum Numberl -number :

• Sublevels within an energy level.

• Sublevels identify the shape of the orbitals.

• There are four different sublevels: s, p, d, f

Orbital ShapesOrbital Shapes

A maximum of 2 electrons can move in each orbital.

Infinite Campus UpdateInfinite Campus Update

• Electron properties and movement quiz (10pts.)

• Flame Test Lab (15 pts.)

Due Today: Electron Probability Lab (15pts.)

Bell Ringer: Electron Arrangement1. What atomic model best explains electron arrangement?

2. a. What is the n-quantum number?

b. T or F: Electron move around the nucleus in

an exact path.

3. a. What is the l-quantum number?

b. Illustrate the s, p, d, f atomic orbitals?

c. How many electrons can move in each atomic orbital at any one time?

Orbital ShapesOrbital Shapes

A maximum of 2 electrons can move in each orbital.

Orbitals and Energy RequirementOrbitals and Energy Requirement• Electron movement defines orbital shapes for each

sublevel.

• Electrons need energy to move in orbital shapes.

Sublevel’s Orbitals Energy for electron movement(Rank in increasing amount of energy)

S-orbital 1 (least energy)

P-orbital 2

D-orbital 3

F-orbital 4 (most energy)

Electron Sublevels (atomic orbitals)Electron Sublevels (atomic orbitals) Diagonal Rule Diagonal Rule

1. Use the diagram to determine the type of sublevels (orbitals) in each energy level?1st: 2nd:3rd:4th:5th:6th:7th:2. What is the maximum number of electrons in each sublevel?

3. What do you suppose the yellow arrows represent?

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m- Quantum Numberm –number:

• Orientations for each atomic orbital.

• Orbital orientations: The different ways an electron can make an orbital in 3-D space.

S-Orbital OrientationS-Orbital Orientation

• Maximum # of s-orbital electrons on an energy level? • How many s-orbitals are possible on an energy level?

P-orbital OrientationsP-orbital Orientations• Maximum # of p-orbital electrons on an energy level?• How many p-orbitals are possible on an energy level?

D-orbital OrientationsD-orbital Orientations• Maximum # of d-orbital electrons on an energy level?

• How many d-orbitals are possible on an energy level?

F-orbital OrientationsF-orbital Orientations•Maximum # of f-orbital electrons on an energy level?

•How many f-orbitals are possible on an energy level?

Orbital Orientations

Electron ConfigurationElectron Configuration

1. Use the diagram to determine howmany sublevels are in each energy level.1st: 12nd:23rd:34th:45th:46th:3 currently7th:2 currently2. What is the maximum number of electrons in each sublevel? 2

3. What do you suppose the yellow arrows represent?

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Electron ArrangementElectron Arrangement

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Determine the electron arrangement for each neutral element

Neutral Elements Electron Configuration

Hydrogen (H):

Lithium (Li) :

Carbon (C):

Oxygen (O):

Neon (Ne):

Sodium (Na):

Chlorine (Cl):

Helium (He) :

Potassium (K):

Vanadium (V):

Cobolt (Co):

Zirconium (Zr):

Diagonal Rule

Electron ConfigurationElectron Configuration• Electron Configuration: The probable

arrangement of electrons in the ground state of an atom.

Electron Configuration Rules:

• Aufbau Principle: Electrons will move in an orbital of lower energy first. (Electrons are lazy!)

• Pauli Exclusion Principle: Only two electrons can move in an orbital at the same time.

• Hund’s Rule: When electrons can move in orbitals of the same energy, they will prefer to be alone before pairing up. (Electrons are selfish!)

Electron ConfigurationElectron Configuration

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Determine the electron configuration for each neutral element: Neutral Elements Electron

Configuration

Hydrogen (H): 1e- 1s1

Lithium (Li) : 3e- 1s22s1

Carbon (C): 6e- 1s22s22p2

Oxygen (O): 8e- 1s22s22p4

Neon (Ne): 10 e- 1s22s22p6

Sodium (Na): 11e- 1s22s22p63s1

Chlorine (Cl): 17e- 1s22s22p63s23p5

Helium (He) : 2 e- 1s2

Potassium (K): 19e- 1s22s22p63s23p64s1

Vanadium (V): 23e- 1s22s22p63s23p64s23d3

Cobolt (Co): 27e- 1s22s22p63s23p64s23d7

Zirconium (Zr): 40e- 1s22s22p63s23p64s23d104p65s24d2

Diagonal Rule

Electron Configuration of ElementsElectron Configuration of Elements

Electron Configuration Orbital NotationElectron Configuration Orbital Notation

H:

Li:

C:

V:

S-Quantum NumbersS-number :

• The direction an electron spins in an orbital.

• If paired, the electrons will spin in opposite directions.

Electron Configuration with Orbital NotationElectron Configuration with Orbital Notation

Orbitals and Periodic Table