7} Bohr’s Model Fifth Fourth Increasing energy Third Second First Further away from the nucleus means more energy.There is no “in between” energyEnergy LevelsFifthFourthThirdIncreasing energySecondFirstNucleus
8LightThe study of light led to the development of the quantum mechanical model.Light is a kind of electromagnetic radiation.Electromagnetic radiation includes many kinds of wavesAll move at 3.00 x 108 m/s ( c)
9Parts of a WaveCrestWavelengthAmplitudeOriginTrough
10Parts of Wave Origin - the base line of the energy. Crest - highest point on a waveTrough - Low point on a waveAmplitude - distance from origin to crestWavelength - distance from crest to crestWavelength - is abbreviated l Greek letter lambda.
11FrequencyThe number of waves that pass a given point per second.Units are cycles/sec or hertz (hz)Abbreviated n the Greek letter nuc = ln
13Frequency and Wavelength Are inversely relatedAs one goes up the other goes down.Different frequencies of light is different colors of light.There is a wide variety of frequenciesThe whole range is called a spectrumMovie Flame Test
24Light is a Particle Energy is quantized. Light is energy Light must be quantizedThese smallest pieces of light are called photons.Energy and frequency are directly related.
25Energy and Frequency E = hn E is the energy of the photon n is the frequencyh is Planck’s constanth = x Joules sec.joule is the metric unit of Energy
26The Math in Chapter 5Only 2 equationsc = lnE = h nPlug and chug.
27ExamplesWhat is the wavelength of blue light with a frequency of 8.3 x 1015 hz?What is the frequency of red light with a wavelength of 4.2 x 10-5 m?What is the energy of a photon of each of the above?Given h = x Joules sec and the Speed of light equals 3.00 x 108 m/s ( c)
37What is light Light is a particle - it comes in chunks. Light is a wave- we can measure its wave length and it behaves as a waveIf we combine E=mc2 , c= n l, E = 1/2 mv2 and E = hnWe can get De Broglie’s equation l = h/mvThe wavelength of a particle.
38Matter is a Wave Does not apply to large objects Things bigger than an atomA baseball has a wavelength of about1x10-32 m when moving 30 m/sAn electron at the same speed has a wavelength of 1x10-3 cmBig enough to measure.
39The Physics of the Very Small Quantum mechanics explains how the very small behaves.Classic physics is what you get when you add up the effects of millions of packages.Quantum mechanics is based on probability because
40Heisenberg Uncertainty Principle It is impossible to know exactly the location and velocity of a particle.The better we know one, the less we know the other.The act of measuring changes the properties.
41Measuring an Electron To measure where an electron is, we use light But the light moves the electronAnd hitting the electron changes the frequency of the light
42After Before Photon Changes Wavelength Photon Electron Changes VelocityMoving Electron
43The Quantum Mechanical Model Remember energy is quantized and comes in chunks.A quanta is the amount of energy needed to move from one energy level to another.Since the energy of an atom is never “in between” there must be a quantum leap in energy.Schrodinger derived an equation that described the energy and position of the electrons in an atom.
45The Quantum Mechanical Model Things that are very small behave differently from things big enough to see.The quantum mechanical model is a mathematical solutionIt is not like anything you can see.
46The Quantum Mechanical Model Has energy levels for electrons.Orbits are not circular.It can only tell us the probability of findingan electron a certain distance from the nucleus.
47The Quantum Mechanical Model The atom is found inside a blurry “electron cloud”An area where there is a chance of finding an electron.Can be divided into smaller regions in the electron cloud.
48Atomic OrbitalsPrinciple Quantum Number (n) = the energy level of the electronWithin each energy level the complex math of Schrodinger’s equation describes several geometric shapes.The group shape is called the sublevel s,p,d,fIndividual shapes are the electron orbitalsThe orbitals represent regions where there is a high probability of finding an electron.
696g Sublevel Sublevel g starts on the 5th level. 9 shapes 18 electrons max
70Summary # of shapes Max electrons Starts at energy level SL s 1 2 1 p 362d51037144f
71By Energy Level First Energy Level only s orbital only 2 electrons 1s2 Second Energy Levels and p orbitals are available2 in s, 6 in p2s22p68 total electrons
72By Energy Level Third energy level s, p, and d orbitals 2 in s, 6 in p, and 10 in d3s23p63d1018 total electronsFourth energy levels,p,d, and f orbitals2 in s, 6 in p, 10 in d, and 14 in f4s24p64d104f1432 total electrons
73By Energy LevelAny more than the fourth and not all the orbitals will fill up.You simply run out of electronsThe orbitals do not fill up in a neat order.The energy levels overlapLowest energy fill first.
74Writing Electron Configurations the Easy Way Yes there is a shorthand
75Electron Configurations repeat The shape of the periodic table is a representation of this repetition.When we get to the end of the column the outermost energy level is full.This is the basis for our shorthand.
76The Shorthand MethodWrite symbol of the noble gas before the element, in [ ].Then, the rest of the electrons.Aluminum’s full configuration:1s22s22p63s23p1previous noble gas Ne is: 1s22s22p6so, Al is: [Ne] 3s23p1
77The Shorthand Again Sn- 50 electrons The noble gas before it is Kr Takes care of 36Next 5s2Then 4d10Finally 5p2[ Kr ]5s24d105p2
78Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p Aufbau Diagram shows the energy of each sublevel and the order they fill with electronsEach box represents an atomic orbital
79Electron Configurations The way electrons are arranged in atoms.Aufbau principle- electrons enter the lowest energy first.This causes difficulties because of the overlap of orbitals of different energies.Pauli Exclusion Principle- at most 2 electrons per orbital - different spins
80Electron Configuration Hund’s Rule- When electrons occupy orbitals of equal energy they don’t pair up until they have toLet’s determine the electron configuration for PhosphorusNeed to account for 15 electrons
81Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p The first two electrons go into the 1s orbitalNotice the opposite spinsSame as Helium1s2only 13 more
82Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p The next electrons go into the 2s orbital‘Be’ on periodic table1s22s2only 11 more
83Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p The next electrons go into the 2p orbitalsNeon on periodic table1s22s22p6only 5 more
84Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s 3p The next electrons go into the 3s orbital‘Mg’ on periodic tableOnly 3 more1s22s22p63s2
85Increasing energy 7p 6d 5f 7s 6p 5d 6s 4f 5p 4d 5s 4p 3d 4s The last three electrons go into the 3p orbitals.They each go into separate orbitals3 unpaired electrons1s22s22p63s23p3
87Fill from the bottom up following the arrows 2s 2p3s 3p 3d4s 4p 4d 4f5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f1s2 2s24 electrons
88Fill from the bottom up following the arrows 2s 2p3s 3p 3d4s 4p 4d 4f5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f1s2 2s2 2p6 3s212 electrons
89Fill from the bottom up following the arrows 2s 2p3s 3p 3d4s 4p 4d 4f5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f1s2 2s2 2p6 3s2 3p6 4s220 electrons
90Fill from the bottom up following the arrows 2s 2p3s 3p 3d4s 4p 4d 4f5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s238 electrons
91Fill from the bottom up following the arrows 2s 2p3s 3p 3d4s 4p 4d 4f5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s256 electrons
92Fill from the bottom up following the arrows 2s 2p3s 3p 3d4s 4p 4d 4f5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s288 electrons
93Fill from the bottom up following the arrows 2s 2p3s 3p 3d4s 4p 4d 4f5s 5p 5d 5f6s 6p 6d 6f7s 7p 7d 7f1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f14 6d10 7p6118 electrons
94Exceptions to the Rule in Electron Configuration
95Orbitals Fill Order Lowest energy to higher energy Adding electrons can change the energy of the orbitalHalf filled orbitals have a lower energyMakes them more stableSometimes changes the filling order
96Write These Electron Configurations Titanium - 22 electrons1s22s22p63s23p64s23d2Vanadium - 23 electrons 1s22s22p63s23p64s23d3Chromium - 24 electrons1s22s22p63s23p64s23d4 is expectedBut this is wrong!!
97Chromium is Actually 1s22s22p63s23p64s13d5 Why? This gives us two half filled orbitalsSlightly lower in energyHolds true for other group 6 elements Cr, Mo, W, and probably SgThe same principal applies to copper Cu and group 11 elements
99Cu’s Electron Configuration Copper has 29 electrons so we expect1s22s22p63s23p64s23d9But the actual configuration is1s22s22p63s23p64s13d10This gives one filled orbital and one half filled orbital.Same is true for ‘Silver’ Ag and ‘Gold’ Au and probably ‘Unununium’ Uuu