Electron Properties and ArrangementChapter 5

Objectives:

• Identify and connect the properties of light with electrons.

• Observe how electrons move in atoms.

• Investigate how the quantity and organization of electrons can distinguish atoms from one another.

Electrons in AtomsElectrons in AtomsWhat do you know about electrons in atoms?

Electrons and Light ParticlesElectrons and Light Particles

Similarities:

• Very tiny particles

• Extremely small masses

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

Wave-Like PropertiesWave-Like Properties• Crest = • Trough= • Wavelength = • Amplitude=

Wave-Like PropertiesWave-Like PropertiesFrequency (υ) :

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?

Electromagnetic Spectrum Applications

• Wavelength and Frequency are indirectly related to one another.

λ = c/υ λ = wavelength (metric units) c = speed of light (3.0x108m/s) υ = frequency (Hz or 1/s)

• Energy and Frequency are directly related to one another.

E= h υ E = energy emitted (Joules) h= Plank’s constant (6.6 x 10-34Js) υ = frequency (Hz or 1/s)

Electromagnetic Spectrum Calculations

a. Calculate the wavelength of a yellow light

emitted by the sodium lamp if the frequency of the yellow light is 5.10x1014 Hz. (λ = c/v )

b. Using data from above, calculate how much energy the yellow light is radiating. (E= hv )

Bell Ringer 10/18/11Bell Ringer 10/18/111. An Iodine atom has 54 electrons.

a. Is it a cation, anion, or neutral atom?

b. Express its symbol with correct charge if applies.

2. A Manganese atom has 23 electrons.

a. It is a cation, anion, or neutral atom?

b. Express its symbol with correct charge if applies.

3. Draw a wave and label its crest, trough, amplitude and wavelength.

Bell Ringer 10/18/11Bell Ringer 10/18/111. An Iodine atom has 54 electrons.

a. Is it a cation, anion, or neutral atom?

b. Express its symbol with correct charge if applies.

2. A Manganese atom has 23 electrons.

a. It is a cation, anion, or neutral atom?

b. Express its symbol with correct charge if applies.

3. a. Draw a wave and label its crest, trough, amplitude, and wavelength.

b. Draw another wave that exhibits a higher frequency.

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?

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

Continuous Spectrum

Continuous Spectrum = Presence of all light particles in the 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.

Visible Spectrum LabVisible Spectrum Lab• Predict and observe the absorption spectrums of

several samples of matter.

Atoms Interaction with Light ParticlesAtoms Interaction with Light Particles

Light Particles

Atom

Electrons absorb light particles

•Electrons absorb specific light particles or photons.•Photons = light particles identified by energy they give off•Electrons that absorb photons move to higher energy levels.

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.

Bell Ringer: Electron MovementBell Ringer: Electron Movement• What are photons?

• What are energy levels?

• Explain the movement of electrons in an atom using the following terms:

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

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.

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.

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.

Emission Spectrum Emission Spectrum =Reveals what photons are

emitted during electron movement.

Ex. Hydrogen Light

chemed.chem.purdue.edu

Emission Spectrums

•Emission spectrum for each element is unique.

Bell RingerBell Ringer1. What is an emission spectrum?

2. Why can scientists identify elements by their emission spectrums?

3. Determine if a purple photon or red photon emits more energy?

Emission Spectrum Emission Spectrum =Reveals what photons are

emitted during electron movement.

Ex. Hydrogen Light

chemed.chem.purdue.edu

Electron Movement in Energy LevelsElectron Movement in Energy Levels

•Each photon emitted determines what energy levels the electron is moving between. -For electron movement to occur, electrons must absorb or emit a specific quantum of energy. •Quantum of energy: Energy difference between energy levels.

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?

Electron Movement in Energy LevelsElectron Movement in Energy Levels•Each energy level has an energy value. •Quantum of energy: Energy difference between energy levels. -For electron movement to occur, electrons must absorb or emit a specific quantum of energy.

Emission Spectrums

•Emission spectrum for each element is unique.

Locating an ElectronLocating an Electron

• Is it possible to know the position and velocity of an electron at any time?

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.

The Quantum Atomic ModelThe Quantum Atomic Model

• An atomic model that best explains the probable movement and arrangement of electrons at any moment in time.

• Schrodinger proved 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 the same path or shape around the nucleus.

Atomic orbital: Probable paths an electron could take around the nucleus.

n-Quantum Numbern-Quantum Number n = energy levels

?

• E- do not travel in the same path or shape around the nucleus.

Atomic orbital: Probable paths an electron could take around the nucleus.

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

n-Quantum Numbern-Quantum Number n = energy levels

• Limited number of electrons on each energy level.

(2n2 Rule )

What is the maximum number of electrons on each energy level below: 2n2

n=1 :

n=3 :

l –Quantum Numberl -number :

• Sublevels within an energy level.

• Sublevels identify the shape of the orbitals (paths).

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

Orbital ShapesOrbital Shapes

Pauli Exclusion Rule

• Maximum number of electrons in an orbital is two.

Orbital SublevelsOrbital Sublevels• Electron movement determines type of sublevel.

• Electrons need energy to move in these sublevels.

Sublevel’s Orbitals Energy for electron movement

How many types of sublevels are in each energy level?How many types of sublevels are in each energy level?

n= energy levels l = sublevels

1

2

3

4

5

6

7

Orbitals and Periodic Table

m- Quantum Numberm –number:

• The number of orientations for each sublevel.

• Sublevel Orientations: How many ways an electron can make a sublevel in 3-D space.

S-Orbital OrientationS-Orbital Orientation

• How many orientations are possible for s-orbitals?

P-orbital OrientationsP-orbital OrientationsHow many orientations are possible for s-orbitals?

D-orbital OrientationsD-orbital Orientations• How many orientations are possible for d-orbitals?

F-orbital OrientationsF-orbital Orientations•How many orientations are possible for f-orbitals?

Orbital Orientations

Electrons in OrbitalsElectrons in Orbitals

Pauli Exclusion Principle: A maximum of two electrons can occupy an orbital at any time.

S-Quantum NumbersS-number :

• The direction an electron moves in a sublevel.

Electron Configuration

Using quantum numbers to distinguish each electrons movement and arrangement from one another in an atom.

Electron Configuration

• Pauli Exclusions Principle: An orbital can hold a maximum of two electrons.

• Aufbau Principle: Electrons will occupy orbitals of lowest energy level first.

• Hund’s Rule: When filling up orbitals with multiple orientations, electrons will want their own orbital before pairing up.

Bell Ringer: Quantum NumbersBell Ringer: Quantum Numbers Color-code the sublevels on the periodic table most

recently given to you.

Electron Configuration

H:

Electron Configuration

He:

Electron Configuration

Li:

Electron Configuration

N:

Bell Ringer: Electron ConfigurationBell Ringer: Electron Configuration1. What is electron configuration?

2. Share your homework with a buddy: To determine the electron configuration of 3 elements on the third row of the periodic table.

Electron Configuration

Electrons in OrbitalsElectrons in Orbitals

Pauli Exclusion Principle: A maximum of two electrons can occupy an orbital at any time.

Bell Ringer: Electron ConfigurationBell Ringer: Electron Configuration1. What sublevels are on n=3?2. What is the maximum number of electrons on n=4 ?

3. When an electron moves from n=6 to n=3, has a photon been absorbed or emitted? Explain.

4. Which electron movement below gained more energy? n=3 to n=7 or n=2 to n=4?

5. Determine the electron configuration for: Sn

Electron ConfigurationElectron Configuration

Exit Slip: Electron ConfigurationExit Slip: Electron Configuration1. What sublevels are on n=3?

2. When an electron moves from n=6 to n=3, has a photon been absorbed or emitted? Explain.

3. Which electron movement gains more energy?

n=3 to n=7 or n=2 to n=4?

4. Determine the electron configuration for: Sn