Presentation on theme: "Chemistry Warm Up Some Dimensional Analysis Review."— Presentation transcript:
1Chemistry Warm Up Some Dimensional Analysis Review. PLEASE SHOW YOUR WORK USING CONVERSION FACTORS AND DIMENSIONAL ANALYSISIf 6.02 x 1023 atoms of carbon have a mass of 12.0 grams, what the mass of x 1023 atoms of carbon atoms. Hint: set up the equality that you know. Make two conversion factors and use one to solve the problem. Check your work using dimensional analysis.2. How many atoms are there in sample of carbon that weighs 30.0grams?3. How many atoms are there in a sample that weighs 3.60 x 102 grams?
2Chemistry Warm Up: Periodic Table Scavenger Hunt The periodic table is arranged by atomic number, not by atomic mass. Find a sequence of three elements that are arranged by atomic number but not by atomic mass.2. Find three elements whose symbols don’t seem to have anything to do with their names. Write the name and the symbol for each.3. There are two rows at the bottom of the periodic table. Use the atomic number to figure out where they fit in to the periodic table.4. What would the periodic table look like if those two rows were inserted in order of their atomic number? Make a sketch.
3Chapter5.1 Models of the Atom California State Science Standards Chemistry1. The periodic table displays the elements in increasing atomic number and shows how periodicity of the physical and chemical properties of the elements relates to atomic structure. As a basis for understanding this concept:g.* Students know how to relate the position of an element in the periodic table to its quantum electron configuration and to its reactivity with other elements in the table.i.* Students know the experimental basis for the development of the quantum theory of atomic structure and the historical importance of the Bohr model of the atom.
4Chapter5.1 Models of the Atom Dalton- Indivisible AtomJ.J.Thomson discovers subatomic particle“Plum pudding,” model
5Development of Atomic Models Rutherford’s Model Dense central NucleusElectrons orbit like planetsAtom mostly empty spaceDoes not explain chemical behavior of atoms
6The Bohr Model Electrons orbit the nucleus Specific circular orbits Quantum = energy to move from one level to another
7The Bohr Model Energy level like rungs of the ladder The electron cannot exist between energy levels, just like you can’t stand between rungs on a ladderA quantum of energy is the amount of energy required to move an electron from one energy level to another
8The Bohr ModelEnergy level of an electron analogous to the rungs of a ladderBut, the rungs on this ladder are not evenly spaced!
9Quantum Mechanical Model Energy quantized; comes in chunks.A quantum 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.1926 Erwin Schrodinger equation described the energy and position of electrons in an atom
10Quantum Mechanical Model •Things that are very small behave differently from things big enough to see.•The quantum mechanical model is a mathematical solution•It is not like anything you can see.
11Quantum Mechanical Model •Has energy levels for electrons.•Orbits are not circular.•It can only tell us the probability of finding an electron a certain distance from the nucleus.
12Atomic Orbitals•Energy levels (n=1, n=2…)•Energy sublevels = different shapes•The first energy levelhas one sublevel:1s orbital -spherical
13Atomic Orbitals•The second energy level has two sublevels, 2sand 2pThere are 3 p-orbitals
14•The third energy level has three sublevels, 3s Atomic Orbitals•The third energy level has three sublevels, 3s3pAnd 5 3d orbitalspy
15Atomic Orbitals•The forth energy level has four sublevels, 4s4p4d orbitalsAnd seven 4f orbitals
16Atomic Orbitals The principal quantum number (energy level) equals the number sublevels
175.2 Electron Arrangement in Atoms Electron ConfigurationElectrons and nucleus interact to produce most stable arrangement=Lowest energy configuration
18Aufbau Principle Electrons fill the lowest energy orbitals first 3 rules:Aufbau Principle Electrons fill the lowest energy orbitals firstHydrogen has 1 electron1s1
193 rules:Pauli Exclusion Principal- two electrons per orbital (one spin up, one spin down)Boron has 5 electrons1s22s22p1
203 rules:Hund’s rule- In orbitals with equal energy levels, arrange spin to maximize electrons with the same spin1s22s22p3Nitrogen has 7 electronsHund’s Rule: Separate the three 2p elecrons into the three available 2p orbitals to maximize the electrons with the same spin.
21Conceptual Problem p135 1s2 2s2 2p6 3s2 3p3 Electron Configuration for Phosphorus (atomic # = 15)1s22s22p63s23p3
22Practice Problem 8a p135 1s2 2s2 2p2 Electron Configuration for Carbon (atomic number = 6)1s22s22p2
23Practice Problem 8b p135 1s2 2s2 2p6 3s2 3p6 Electron Configuration for Argon (atomic # = 18)1s22s22p63s23p6
24Practice Problem 8c p135 1s2 2s2 2p6 3s2 3p6 3d8 4s2 Electron Configuration for Nickel (atomic # = 28)1s22s22p63s23p63d84s2
25Practice Problem 9a p135 1s2 2s2 2p1 1 Electron Configuration for Boron (atomic # = 5)1s22s22p1How many unpaired electrons?1
26Practice Problem 8c p135 1s2 2s2 2p6 3s2 3p2 2 Electron Configuration for Silicon (atomic # = 14)1s22s22p63s23p2How many unpaired electrons?2
27Exceptions to the Aubau Rule Copper atomic number=291s22s22p63s23p63d94s2This is the expected electron configuration
28Exceptions to the Aubau Rule Copper atomic number=291s22s22p63s23p63d104s1Half-filled and filled sublevels are more stable, even if it means stealing an electron from a nearby sublevelThis is the actual electron configuration.
29Exceptions to the Aubau Rule Chromium atomic number=241s22s22p63s23p63d44s2This is the expected electron configuration
30Exceptions to the Aubau Rule Chromium atomic number=241s22s22p63s23p63d54s1Half-filled and filled sublevels are more stable, even if it means stealing an electron from a nearby sublevelThis is the actual electron configuration.
315.3 Physics and the Quantum Mechanical Model Or, “How do they get all those colors of neon lights?”
32Goals•Describe the relationship between wavelength and frequency of light•Identify the source of atomic emission spectra•Explain how frequency of emitted light are related to changes in electron energies•Distinguish between quantum mechanics and classical mechanics
33Quick review of wave terminology Amplitude = height of waveWavelength = distance between crestsFrequency = number of crests to pass a point per unit of time
34Light waves Amplitude = height of wave Wavelength = distance between crestsFrequency = number of crests to pass a point per unit of timeFor light, the product of frequency and wavelength = speed of light, cFrequency • Wavelength = 3.00 x 108So, as the frequency of light increases, the wavelength decreases
35Electromagnetic Spectrum Visible light is only part of the electromagnetic spectrum:
36Wavelength of Light p140Sample Problem: What is the wavelength of yellow light from a sodium lamp if the frequency is 5.10 x 1014 Hz (Hz = s-1)Wavelength • frequency = 3.00x108m/sWavelength = 3.00x10-8 m/s / frequencyWavelength = 3.00x108m/s / 5.10x1014 s-1Wavelenght = 5.88 x 10-7 m
37Wavelength of Light p140#14:What is the wavelength of radiation if the frequency is 1.50x1013 Hz (Hz = s-1)?Is this longer or shorter than the wavelenght of red light?Wavelength • frequency = 3.00x108m/sWavelength = 3.00x108 m/s / frequencyWavelength = 3.00x108m/s / 1.50x1013 s-1Wavelength = 2.00 x 10-5 mLonger than red lightwhich if between 10-6 and 10-7 m
38Wavelength of Light p140#15: What is the frequency of radiation if the wavelength is 5.00x10-8 Hz (Hz = s-1)In what range of the electromagnetic specrum is this?Wavelength • frequency = 3.00x108m/sfrequency = 3.00x108 m/s / wavelengthfrequency = 3.00x108m/s / 5.00x10-8mFrequency = 6.00 x 1015 s-1ultraviolet
39Atomic Spectra When atoms absorb energy, Electrons move to higher energy levels.When electrons return to the lower energy level, they emit lightEach energy level produces a certain frequency of light resulting in an emission spectrum
40Atomic Spectra Emission spectra are like a fingerprint of the element We know what stars are made of by comparing their emission spectra to that of elements we find on earth
41Explanation of Atomic Spectra Emission spectra like a fingerprint of the elementWe know what stars are made of by comparing their emission spectra to that of elements we find on earth