AP Chemistry Name:
CHAPTER 7
ATOMIC STRUCTURE and PERIODICITY
HW: Warning: If you do not normally read the chapter, please start NOW with chapter 7. This chapter is very conceptual (vs. plug and chug), so complete understanding will require more than simply completing the HW assignment. See HW assignment online.
PERIODIC TABLE ASSIGNMENT #2
Consult chapter 7, 10, 19, 20, 21
Add the following information to your large periodic table.
1. Below the appropriate groups, label the following electron configuration endings: s1, s2, p1, p2,p3, p4,p5,p6,d1-d10, f1-f14
2. Write chromium’s electron configuration below the element symbol.
3. Write copper’s electron configuration below the element symbol.
4. Draw the trend for increasing ionization energy on your table (or below it in a small box).
5. Draw the trend for increasing electron affinity on your table (or below it in a small box).
6. Draw the trend for increasing electronegativity on your table.
7. Find the most electronegative atom on the table and write its electronegativity value (from the Pauling scale) in its box.
8. Find the least electronegative atom on the table and do the same as in the last exercise.
9. Find an element that is a yellow crystalline solid and color its box yellow.
10. Find the element that is gold and color its box gold.
11. Find the element known as “quicksilver” and write its name and symbol and color it silver.
12. Find the element that is a violet – black crystal and color its box purple.
13. Find the element that is a red-brown liquid and color its box accordingly.
14. Find the element that is a yellow-green poisonous gas and color its box accordingly.
15. Find three noble gases that will actually form compounds. List a few of their compounds in their boxes.
16. Find a noble gas that is a major component of the sun and whose nucleus is known as an alpha particle. Write and alpha symbol in its box.
17. Find an element that can form a peroxide or a superoxide and write the general formulas for each in its box.
18. This metallic element is prepared from bauxite. Find it and write the formula for bauxite in its box.
19. This metallic element melts at 30ºC. Write this fact in its box.
20. This metallic element is prepared from cassiterite. Find it and write the formula for cassiterite in its box.
21. This metallic element can be prepared from galena. Find it and write the formula for galena in its box.
22. This element is the most abundant in the earth’s crust. Write crust in its box.
23. This element is the most abundant in the atmosphere. Write atmosphere in its box.
24. This element comes in black, white, or red. Color it accordingly.
25. This element has forms called monoclinic and rhombic. List these terms in its box. Color the box appropriately.
CHAPTER 7 OVERVIEW
(7.1-7.2) Electromagnetic radiation, solving for wavelength and frequency, quantized energy, Debroglie relationship for calculating wavelength of a particle, particle wave duality and continuous vs. discrete line spectrum.
(7.3-7.4) The Bohr model of the atom, energy calculations for electron transitions. (see Bohr lab)
(7.5) Quantum mechanical view of the atom, Heisenberg uncertainty principle, electron probability distributions.
(7.6-7.7) Quantum numbers n, l, ml and ms and orbital shapes and energies.
(7.8-7.11) Pauli exclusion, Hund’s rule and aufbau principle.
(7.12) Shielding effect, Z effective (eff. Nuclear charge), ionization energy, orbital filling across a period.
(7.13) Trends of the first and second ionization energy, electron affinity, electronegativity, and atomic radius.
UNDERSTANDING BOHR’s MODEL of the ATOM
To understand the ring model that Bohr proposed, we have to understand how an electron is moving.
PARTICLE WAVE DUALITY
Who?
What? The electron can travel as a particle or as a wave.
All matter has particle/ wave like properties. Some have such a small wavelength that we don’t notice.
When?
WAVE MOTION
· Characteristic of all electromagnetic radiation (EMR)
ROYGBIV = visible region ranging from ______to ______nm.
· Wave motion is described by:
1. Wavelength
Defined as: the ______between two crests of a wave
Symbol:
Units:
2. Amplitude
Defined as: ______of the wave (from rest to crest)
Symbol:
Units:
3. Frequency Rays
Defined as: the ______of waves that pass per second
Symbol:
Units:
1 hz = 1/ second
106 hz = 1 Megahertz
· All EMR travels at the speed of light.
c = 2.9979 x 108 m/s
we will use ______m/s
· Relationship between c, l, and n
Ex. What is the wavelength of light that has a frequency of 5.0 Hz? Is this visible?
Ex. What is the frequency of blue light with a wavelength of 484 nm?
PRIOR to DeBROGLIE
Matter and energy were seen as different from each other in fundamental ways.
Matter was treated as a particle.
Energy could come in waves, with any frequency. Until,
Who?
What? Found that the colors of light emitted from hot objects (heated to incandescence) couldn’t be explained by viewing energy as a wave.
Instead, he proposed that light was given off in the form of photons with a discrete amount of energy called ______.
When?
HOW? Can the energy of a photon can be calculated?
Where:
E is energy
h is Planck’s constant = ______
n is frequency
Ex. What is the energy associated with light with a frequency of 6.65 x 108 / second?
Who?
What? Said electromagnetic radiation is quantized in particles called photons.
When?
Each photon has energy E = or E=
Combine this with E =
Apparent mass of a photon of light:
Or
Apparent wavelength of an object with mass:
DEBROGLIE WAVELENGTH
Does matter have a wavelength?
Does light energy have mass?
Treating matter as a wave:
· Use the velocity v to find wavelength
· This wavelength is known as the ______or the
______.
DeBroglie’s equation:
Ex. Sodium atoms have a characteristic color when excited in a flame. The color comes from the emission of light of 589.0 nm.
What is the frequency of this light ?
What is the energy of a photon of this light ?
What is the apparent mass of a photon of this light ?
What is the energy of a mole of these photons?
Ex. What is the wavelength of an electron travelling at 1.0 x 107 m/s?
Mass of e-1 = 9.11 x 10-31 kg
Ex. What is the wavelength of a softball with a mass of 0.10 kg moving at 99 mi/hr?
SPECTROSCOPY
The study of ______as it interacts with ______.
Initial spectroscopy experiments provided evidence about the early atomic model.
Ex. Bohr model based on ______and AES
Ex. ______/ Photoemission spectroscopy (PES) leading to the Shell/ Subshell model
Other types of spectroscopy used in analytical chemistry:
AAS spectroscopy
AES spectroscopy
IR spectroscopy
NMR spectroscopy
Raman Spectroscopy
UV/VIS spectroscopy
X-Ray spectroscopy
CONTINUOUS SPECTRUM
· The range of frequencies present in light.
· ______has a continuous spectrum.
· All the colors are possible.
· A rainbow can be seen through a ______.
DISCRETE LINE SPECTRUM
Hydrogen spectrum
· Emission spectrum because these are the colors it gives off or emits.
· Called a ______spectrum.
· There are just a few discrete lines showing. What this means:
o Only certain energies are allowed for the hydrogen atom.
o Can only give off certain energies.
o Energy in the in the atom is ______.
· Use E = hn = hc / l 4
·
The Balmer Series: Visible lines at
______.86 nm
Also lines in the UV ______and
The IR ______.
Who?
What? Developed the quantum model of the hydrogen atom.
He said the atom was like a solar system.
The electrons were attracted to the nucleus because of opposite charges.
Didn’t fall in to the nucleus because the e was constantly moving around.
The Bohr Ring Model of the Atom
He didn’t know why but only certain energies were allowed.
He called these allowed energies energy levels.
Putting Energy into the atom moved the electron away from the nucleus from ground state to excited state. When it returns to ground state it gives off light of a quantifiable energy.
n is the ______
n = ______is called the ______
Z is the ______, which is +1 for hydrogen.
For each energy level the energy is:
E = -2.178 x 10-18 J (Z2 / n2)
When the electron is removed, n =______, E = ______
n≠______mathematically undefined.
We are worried about the change when the electron moves from one energy level to another.
ΔE = ______
ΔE = -2.178 x 10-18J Z2 (1/ nf2 - 1/ ni2)
Ex. Calculate the energy need to move an electron from its ground state to the third energy level. Would visible light be energetic enough to cause this transition?
Ex. Calculate the energy released when an electron moves from n= 4 to n=2 in a hydrogen atom.
Ex. Calculate the wavelength of light given the last transition. Is this light visible?
Ex. Calculate the energy released when an electron moves from n= 5 to n=3 in a He+1 ion.
QUANTUM MECHANICAL VIEW OF THE ATOM
Considers the wave and particle nature of light simultaneously. Presents the most probable locations for finding an electron based on its wave function and its energy.
WAVE THEORY
A ______exitst between two fixed points.
There are only certain ______at which the wave can travel because the
ends are fixed. Set frequencies lead to set ______and
______energy values.
Waves can be defined by their number of ______These are areas when the wave
goes from ______in value.
0 nodes = the ______. It has the lowest frequency and the longest wavelength. This is known as the ground state in the atom. This is the n=1 level. Sometimes called the
______.
All other frequencies will be a multiple of the fundamental frequency.
} 1 node = the ______. The n=2 energy level (1 central node, 2 fixed nodes)
} 2 nodes = the ______. The n = 3 energy level (2 central nodes, 2 fixed nodes)
And so on…
HOW CAN THE ELECTRON’s POSTION or MOTION BE DESCRIBED?
y = the ______, which tells the 3-D coordinates of the e- position.
y is part of the SCHRODINGER equation.
- h 2 d2y = E y
2 m dx2
where h is a modification of Planck’s constant = h / 2p = 1.05457 x 10-34 Js
m = the mass of the particle
E is the energy of the wave function
and the d2 term means to take the 2nd derivative of the function
The solution of the calculus based equation results in 4 ______numbers, which tell us something about the electron’s behavior. More on these later.
y2 = the probability of finding an electron in a particular point in space called an ______.
Can be shown as a ______distribution. Where the highest point is the most likely distance from the nucleus to find the electron. When n= 1 this distance also coincides with the first “orbit” predicted by BOHR.
Probability density for n = 1 for the H atom
Unfortunately, the electron’s position and momentum cannot be known at the same time.
This is the ______principle.
D x · D mv = h / 4p
Where Dx is the uncertainty about the ______.
D mv is the uncertainty about the ______.
So, the more you know about the electron’s position, the less you can know about its movement (momentum). In macroscopic systems, this uncertainty is negligible.
QUANTUM NUMBERS
The solution set to the Schrodinger equation. Every electron in the atom can be defined by a unique set of quantum numbers.
Principle quantum number
Symbol:
What does it tell about the electron?
Values:
Angular quantum number
Symbol:
What does it tell about the electron?
Values:
*See orbital shapes handout and additional orbitals in 3D linked to wikispace.
Magnetic
Symbol:
What does it tell about the electron?
Values:
Spin
Symbol:
What does it tell about the electron?
Values:
ENERGY LEVEL DIAGRAMS
RULES for FILLING the DIAGRAM
· ______– “building up” - fill orbitals in lower energy levels before proceeding to the next level.
· ______- Place electrons in separate orbitals before pairing them within the same energy level. This minimizes energy by minimizing the repulsion between electrons.
· ______– every electron must have a different set of quantum numbers. Electrons in the same orbital must have opposite spins.
ELECTRON CONFIGURATION
· Shows the filled orbitals in short hand notation.
Ex. Mg
Ex. Cl
NOBLE GAS electron configuration: shows the noble gas core to simplify electron configuration.
· Focuses on valence electrons - the electrons in the outermost energy levels (not including d).
Ex. O
Ex. Br
Ex. U
How is electron configuration related to the periodic table?.
· Elements in the same ______have the same electron configuration.
· Put in columns because of ______.
· Similar properties because of electron configuration, allows us to predict trends.
· Noble gases have ______energy levels.
· Transition metals are filling the ______.
· Exceptions to filling rules:
Ex. Cr =
Ex. Cu=
· These have half filled orbitals.
· Scientists aren’t sure of why it happens. Leads to stability due to minimizing electron repulsions.
What experimental evidence exists to support the shell and subshell model (as an alternative to the Borh model)?
PES
*more info available on wikispace, AP central, and in PES lab.
Z EFFECTIVE AND IONIZATION ENERGY
Z effective and Ionization Energy based on POSITION on the periodic table.
Zeffective - is the ______experienced by an electronin a multi-electronatom.