chemistry warm up some dimensional analysis review. please show your work using conversion factors...

Chemistry Warm UpSome Dimensional Analysis Review.

PLEASE SHOW YOUR WORK USING CONVERSION FACTORS AND DIMENSIONAL ANALYSIS

1. If 6.02 x 1023 atoms of carbon have a mass of 12.0 grams, what the mass of 1.51 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?

Chemistry Warm Up: Periodic Table Scavenger Hunt

1. 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.

Chapter5.1 Models of the Atom

California State Science Standards Chemistry

1. 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.

Chapter5.1 Models of the Atom

Dalton- Indivisible Atom QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

J.J.Thomson discovers subatomic particle“Plum pudding,” model



Development of Atomic Models

Rutherford’s Model Dense central Nucleus Electrons orbit like planets Atom mostly empty space Does not explain chemical

behavior of atoms

The Bohr Model

Electrons orbit the nucleus Specific circular orbits Quantum =

energy to movefrom one levelto another

The 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 ladder

A quantum of energy is the amount of energy required to move an electron from one energy level to another

The Bohr ModelEnergy level of an

electron analogous to the rungs of a ladder

But, the rungs on this ladder are not evenly spaced!

Quantum 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


•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.


•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.

Atomic Orbitals

•Energy levels (n=1, n=2…)•Energy sublevels = different

shapes•The first energy level

has one sublevel:1s orbital -spherical

Atomic Orbitals

•The second energy level has two sublevels, 2s

and 2pThere are 3 p-orbitals

Atomic Orbitals

•The third energy level has three sublevels, 3s

3pAnd 5 3d orbitals

py

Atomic Orbitals•The forth energy level has four

sublevels, 4s4p

4d orbitalsAnd seven 4f orbitals







Atomic OrbitalsThe principal quantum number (energy level)

equals the number sublevels

5.2 Electron Arrangement in Atoms

Electron ConfigurationElectrons and nucleus interact

to produce most stable arrangement=

Lowest energy configuration

3 rules:Aufbau Principle Electrons fill the lowest energy orbitals firstHydrogen has 1 electron

1s1

3 rules:Pauli Exclusion Principal- two electrons per orbital (one spin up, one spin down)

Boron has 5 electrons

1s22s22p1

3 rules:Hund’s rule- In orbitals with equal energy levels, arrange spin to maximize electrons with the same spin

Nitrogen has 7 electrons

Hund’s Rule: Separate the three 2p elecrons into the three available 2p orbitals to maximize the electrons with the same spin.

1s22s22p3

Conceptual Problem p135Electron Configuration for Phosphorus (atomic # = 15)

1s22s22p63s23p3

Practice Problem 8a p135Electron Configuration for Carbon (atomic number = 6)

1s22s22p2

Practice Problem 8b p135Electron Configuration for Argon (atomic # = 18)

1s22s22p63s23p6

Practice Problem 8c p135Electron Configuration for Nickel (atomic # = 28)

1s22s22p63s23p6 4s23d8

Practice Problem 9a p135Electron Configuration for Boron (atomic # = 5)

1s22s22p1

How many unpaired electrons?

1

Practice Problem 8c p135Electron Configuration for Silicon (atomic # = 14)

1s22s22p63s23p2

How many unpaired electrons?

2

Exceptions to the Aubau RuleCopper atomic number=29

1s22s22p63s23p6 4s23d9

This is the expected electron configuration

Exceptions to the Aubau RuleCopper atomic number=29

1s22s22p63s23p6 4s13d10

This is the actual electron configuration.

Half-filled and filled sublevels are more stable, even if it means stealing an electron from a nearby sublevel

Exceptions to the Aubau RuleChromium atomic number=24

1s22s22p63s23p6 4s23d4

This is the expected electron configuration

Exceptions to the Aubau RuleChromium atomic number=24

1s22s22p63s23p6 4s13d5

This is the actual electron configuration.

Half-filled and filled sublevels are more stable, even if it means stealing an electron from a nearby sublevel

5.3 Physics and the Quantum Mechanical Model

Or, “How do they get all those colors of neon lights?”





Goals

•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

Quick review of wave terminologyAmplitude = height of waveWavelength = distance between crestsFrequency = number of crests to pass a point per unit of time

Light wavesAmplitude = height of waveWavelength = distance between crestsFrequency = number of crests to pass a point per unit of time

For light, the product of frequency and wavelength = speed of light, cFrequency • Wavelength = 3.00 x 108

So, as the frequency of light increases, the wavelength decreases

Electromagnetic SpectrumVisible light is only part of the electromagnetic spectrum:

Wavelength of Light p140

Wavelength • frequency = 3.00x108m/sWavelength = 3.00x10-8 m/s / frequencyWavelength = 3.00x108m/s / 5.10x1014 s-1

Wavelenght = 5.88 x 10-7 m

Sample Problem: What is the wavelength of yellow light from a sodium lamp if the frequency is 5.10 x 1014 Hz (Hz = s-1)


#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-1

Wavelength = 2.00 x 10-5 m Longer than red lightwhich if between 10-6 and 10-7 m


#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-1

ultraviolet

Atomic SpectraWhen 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

Atomic SpectraEmission spectra are 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

Explanation of Atomic SpectraEmission 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

chemistry warm up some dimensional analysis review. please show your work using conversion factors...

Documents

quantum of energy

model slide

atom slide

bohr model energy level

atomic number

atomic mass

energy levels

quantum leap