1 Happy MONDAY, Chemistry! Learning Targets 11.I CAN describe how light is produced. 12.I CAN describe the electromagnetic spectrum. 13.I CAN explain.

Electrons

Happy MONDAY, Chemistry! Learning TargetsI CAN describe how light is produced. I CAN describe the electromagnetic spectrum. I CAN explain the relationships between energy, frequency, and wavelength of a light wave. I CAN use the light equation to calculate wavelength, frequency, and energy of a light wave.

Agenda: The Atom and LightElectromagnetic Spectrum Light Equations Notes on Light

What do you need for class?PencilCalculator Unit 2 PacketComposition Notebook #ELECTROMAGNETIC RADIATION

#Electromagnetic RadiationWavelength (l) = the distance between wave peaks

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What is the difference between these two waves?

So is radiation harmful?

Which wave would be more harmful to you? #Look at the Electromagnetic Spectrum handoutFind Visible light.Which direction is increasing wavelength?Which direction is increasing frequency?Which direction is increasing Energy?#Electromagnetic SpectrumLong wavelength Low frequencyShort wavelength High frequency

increasing frequencyincreasing wavelength

#Page #Light EquationsWe will use two light equations, and one equation that is the combination of the two. You must know how to manipulate these algebraically to solve for each variable. = wavelength = frequency E = energy

c = speed of light h = Plancks constant

#Light Equations

#How do calculations relate to what we saw in the light lab?

Whats this thing called again? #

What are you seeing when you look through the spectroscope?

What is the prism doing?

#Spectrum of Hydrogen Gas

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What are you seeing when you look through the spectroscope?

What is the prism doing?

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#Electricity and Gases

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What you should have seen in your lab.Emission spectra! #

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What causes different colors of light? #

wavelengthVisible lightwavelengthUltaviolet radiationAmplitudeNodeElectromagnetic Radiation#Page #Atomic Line Emission Spectra and Niels BohrBohrs greatest contribution to science was in building a simple model of the atom. It was based on an understanding of the LINE EMISSION SPECTRA of excited atoms.

Niels Bohr(1885-1962)#Line Emission Spectra of Excited AtomsExcited atoms emit light of only certain wavelengthsThe wavelengths of emitted light depend on the element.

#What happens when electrons get excited?

One view of atomic structure in early 20th century was that an electron (e-) traveled about the nucleus in an orbit.

#Remember Niels Bohr?Bohrs greatest contribution to science was in building a simple model of the atom. It was based on an understanding of the LINE EMISSION SPECTRA of excited atoms.

THIS MODEL ONLY WORKS FOR HYDROGEN.

Niels Bohr(1885-1962)#Schrodinger applied idea of e- behaving as a wave to the problem of electrons in atoms.He developed the WAVE EQUATIONSolution gives set of math expressions called WAVE FUNCTIONS, Each describes an allowed energy state of an electron.

E. Schrodinger1887-1961Quantum or Wave Mechanics#Heisenberg Uncertainty PrincipleProblem of defining nature of electrons in atoms solved by W. Heisenberg.Cannot simultaneously define the position and momentum of an electron.We define electron energy exactly but accept limitation that we do not know exact position.

W. Heisenberg1901-1976#Interactives: Remember This? http://www.learner.org/interactives/periodic/elementary.html #Electrons in atoms are according to theirENERGY LEVELS (Size)SUBLEVELS (Shape)ORBITALS (Orientation)

Arrangement of Electrons in Atoms#

n = 1n = 2n = 3n = 4Energy Levels (Size)#Relative sizes of the spherical 1s, 2s, and 3s orbitals of hydrogen.

#The most probable area to find these electrons takes on a shape.

So far, we have 4 shapes. They are named s, p, d, and f.

Sublevels (Shapes)#

s orbitalp orbitald orbital

Sublevels (Shapes)#

s Orbitals (Orientation)No more than 2 e- assigned to an orbital.

One spins clockwise, one spins counterclockwise#

p Orbitals (Orientation)The three p orbitals lie 90o apart in spaceIf no more than 2 e- can fit into each orbital, how many electrons are in the p sublevel? #

If no more than 2 e- can fit into each orbital, how many electrons are in the d sublevel? d Orbitals (Orientation)#

f Orbitals (Orientation)If no more than 2 e- can fit into each orbital, how many electrons are in the f sublevel? #sdNumber oforbitalsNumber of electronspfHow many electrons can be in a sublevel?Remember: A maximum of two electrons can be placed in an orbital.Shape of sublevel#Page #To be honest, we dont exactly know.

Remember Heisenburg said, the more we know about an electrons location, the less we know about its speed. So, by the time we have isolated an electron, it moved anyway.

BUT, based on probabilities, we can assume that electrons are in certain locations. Where are the electrons at any given moment? #TheAufbau principlestates that electrons must fill the lowest energy orbitals first.

Hund's rule states every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied. (Seats on a bus)

The Pauli Exclusion principle states that no more than two electrons can occupy an orbital, and they must do so with opposite spins.Locations of Electrons:The Rules! #Electron ConfigurationsA list of all the electrons in an atomMust go in order (Aufbau principle)2 electrons per orbital, maximum (Hunds Rule)We need electron configurations so that we can determine the number of electrons in the outermost energy level. These are called valence electrons.The number of valence electrons determines the propertied of an atom, including the type of bonds it can make to in order to make a molecule#Diagonal Cheat Sheet!Must be able to write it for the test!

The diagonal rule is a memory device that helps you remember the order of the filling of the orbitals from lowest energy to highest energy_____________________ states that electrons fill from the lowest possible energy to the highest energy But Ms. Kovach,

How will I ever remember all of the rules?!

What do they mean!??!#Diagonal Cheat Sheet!ss 3p 3ds 2ps 4p 4d 4fs 5p 5d 5f 5g?s 6p 6d 6f 6g? 6h?s 7p 7d 7f 7g? 7h? 7i?1234567Steps:Write the energy levels top to bottom.Write the orbitals in s, p, d, f order. Write the same number of orbitals as the energy level.Draw diagonal lines from the top right to the bottom left.To get the correct order, follow the arrows!By this point, we are past the current periodic table so we can stop.#Electron Configurations2p4Energy LevelSublevelNumber of electrons in the sublevel1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 etc.#Lets Try It!Write the electron configuration for the following elements:HLiNNeKZnPb

#Shorthand NotationA way of abbreviating long electron configurationsSince we are only concerned about the outermost electrons, we can skip to places we know are completely full (noble gases), and then finish the configuration#Shorthand NotationStep 1:Find the PREVIOUS noble gas to the atom. Write the noble gas in brackets [ ].

Step 2: Find where to resume by finding the next energy level.

Step 3: Resume the configuration until its finished.

#Lets Try It!Write the shorthand electron configuration for the following elements:HLiNNeKZnPb

#Orbitals and the Periodic TableOrbitals grouped in s, p, d, and f orbitals (sharp, proximal, diffuse, and fundamental)

sdpfBut Ms. Kovach,

How am I going to remember the diamond cheat sheet ..and the shorthand shortcut

.and EVERYTHING ELSE?

#Lets Try It!Write the electron configuration for the following elements:HLiNNeKZnPb

#Electron Configuration: ChlorineLonghand is 1s2 2s2 2p6 3s2 3p5

You can abbreviate the first 10 electrons with a noble gas, Neon. [Ne] replaces 1s2 2s2 2p6 The next energy level after Neon is 3

So you start at level 3 on the diagonal rule (all levels start with s) and finish the configuration by adding 7 more electrons to bring the total to 17[Ne] 3s2 3p5

#Practice Shorthand NotationWrite the shorthand notation for each of the following atoms:ClKCaIBi#Orbital DiagramsGraphical representation of an electron configurationOne arrow represents one electronShows spin and which orbital within a sublevelSame rules as before (Aufbau principle, Pauli Exclusion principle, and Hunds Rule). #LithiumGroup 1AAtomic number = 31s22s1 3 total electrons

#CarbonGroup 4AAtomic number = 61s2 2s2 2p2 6 total e-

Here we see for the first time HUNDS RULE. When placing electrons in a set of orbitals having the same energy, we place them singly as long as possible.

#Draw these orbital diagrams!Oxygen (O)Chromium (Cr)Bromine (Br)

#Interactives: Remember This? http://www.learner.org/interactives/periodic/elementary.html #