CHEM 1320 Lecture Notes - Lecture 26: Pauli Exclusion Principle, Aufbau Principle

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limegerbil338

19 Mar 2018

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Quantum numbers: what versus why, mendeleev"s periodic law allows us to predict what the properties of an element will be based on its position on the table. 2. the electrons in atoms exist in orbitals: a description of the orbitals occupied by electron is called an electron con guration. B. the property of electron spin: spin: fundamental property of all electrons, all electrons have the same amount of spin. !1: orientation of the posit is quantized; it can only be up or down . Tuesday, april 4, 2017: electron"s spin: fourth quantum number, spin quantum number, not in the schrodinger, spin quantum number, ms, and orbital diagrams, values: plus or minus 1/2. !2: electron con guration: how the electrons are distributed among the various atomic orbitals in an. Tuesday, april 4, 2017 atom: valence electrons: outermost electrons, highest principal quantum number, most likely to be involved in reactions, core electrons: inner electrons.

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please answer questions 12- 18

Quantum mechanics is a very complex theory. A good way to help you remember it is to compare it to an apartment building. An apartment building has different floors, different apartments on each floor, and different rooms within each apartment. We can look upon the electrons of an atom as rather peculiar apartment dwellers. Electrons prefer the floor closest to the ground and the smallest apartments. Electrons also prefer to live one to a room until each room in an apartment has one occupant. The electrons will then pair up until each room has two. Each room in an apartment can hold two electrons Apartment buildings have several floors. The model we discuss has several floors, but only the first 7 floors will be occupied. All the electrons known today will fit within 7 floors of the building. Additional floors are available but will only be occupied in special situations. The floors in the apartment building are called shells in the electron model and are numbered 1-7. 1) According to what you have just read, what shell will be occupied first by electrons? 2 flers Each shell (or floor) in the model has one or more apartments, which are called subshells. These subshells are apartments of four sizes: s,p,d, and f. An s subshell (apartment) has only a single room. A p subshell has 3 rooms. A d subshell has 5 rooms, while an fsubshell has 7 rooms. An s subshell then will hold a maximum of 2 electrons according to the model. 2) A p subshell will bold a maximum of how many electrons? 3) How many will a d subshell hold? lo e lect@n)ã.ã 4) How many will an fsubshell hold? Iy cles tiou Each room in a subshell is called an orbital. From the previous question we know that a s subshell will consist of one orbital with a capacity (occupancy) of 2 electrons. 5) A p subshell will consist of 3 orbitals with a total subshell capacity of electrons. 6) A d subshell will have 7) Anf subshell will have orbitals and a total capacity of lo_ electrons orbi electrons. The first shell (floor) has only 1 subshell (apartment), which is an s subshell Because of its location on the first shell, it is called a ls subshell 8) How many orbitals(rooms) are there in the Is subshell? 9) How many electrons will the subshell hold?-- a. The second shell (floor) only has an s subshell (apartment) and a p subshell 10) If the s subshell is called 2, what do you suppose the p subshell is called? 11) How many orbitals (rooms) are in that p subshell? 12) How many subshells are in the second shell? 13) How many orbitals are there in the second shell? 14) How many electrons can occupy the second shell? 15) The third shell has 3 subshells: s.p andd 16) What are they called? 17) How many subshells are in the third shell? 18) How many orbitals are in the third shell?

I want to find the Kn value of Cu(II) and EDTA. I was given the formula kn= [ML4]/[ML3][L]. 12.3 ml of edta was used to tritrate 0.1194 grams of Copper in 50 ml of water. The indicator used was murexide.

At the core of general acid-base theories, there is the concept of âtransferâ of one entity to another. In the case of BrÃ¸nsted-Lowry acid base theory, the transferred entity is the proton, and their transfer processes are widely exploited in chemical methods. In addition to proton transfer, electron pairs can also be donated/shared between donors and acceptors. In this case, an atom/molecule, which can accept a pair of electrons, is referred to as a Lewis acid while the entity donating the pair of electrons is referred to as a Lewis base. The most prevalent Lewis acid-base systems involve metal complexes with vacant nd-orbitals, as well as electron deficient systems including B, Si, Ge, etc. The Lewis acid base theory is also known as the Hard-Soft acid base theory (HSABT) with âhardnessâ defined as small highly charged species that are weakly polarizable (Lewis acids). In contrast, âsoftnessâ is described by species that are larger and highly polarizable species with low charge (Lewis bases).
In the case of metal chemistry, Lewis acid-base theory provides a means to describe the ability of âligandsâ to coordinate to metal ions as well as the stability of metal-ligand complexes. Recall that coordination bonds are the donation/acceptance of lone pairs of electrons to empty metal orbitals to another atom; the definition of Lewis acid-base chemistry! The stability of Lewis acid-base complexes can be described through the stability constant which is analogous to the Ka that describes BrÃ¸nsted-Lowry acidities. Many metal ions can coordinate (bind) many Lewis base ligands in a step-wise fashion according to:
M + L = ML K1 = [ML]/[M][L] Eq. 1
ML + L = ML2 K2 = [ML2]/[ML][L] Eq. 2
ML2 + L = ML3 K3 = [ML3]/[ML2][L] Eq. 3
MLn-1 + L = MLn Kn = [ML4]/[ML3][L] Eq. 4
and for which the free energy for this dissociation reaction is given by:
ÎG0 = -RTLnKn Eq. 5.
where R is the gas constant and T is the temperature in Kelvin.
Figure 1: Left- EDTA. Right- Typical EDTA-transition metal complex.
The ethylene diamine tetraacetic acid ligand (EDTA, a Lewis base) provides a mechanism to probe the Lewis acid strength of various metal complexes (Figure 1). This multi-dentate ligand (multiple Lewis base sites on a single ligand) forms complexes with metals of the form:
Mn+ + Y4- = MYn-4 Eq. 6
K = [MYn-4]/[Mn+][Yn-4] Eq. 7
where Y4- is the EDTA ligand.
In this experiment, the Lewis acid strength for two different metals will be examined by measuring the stability constants for the metal-EDTA complex. Of specific interest is the how the Lewis acid strength of the metal ion correlates with:
1) atomic/ionic radii, 2) oxidation state, 3) electron configuration, and 4) polarizability.
You will determine the stability constants of both a Cu2+- and Zn2+-EDTA complexes as well as the corresponding free energy. Using these data, you will compare the relative Lewis acidities of both metals and describe differences in terms of the metal ion properties described above.
.
Chemicals
CuSO4
ZnSO4
EDTA
Murexide
Instruments
Buret
Experimental
You and your group will determine the concentration and ultimately the free energy of Cu(II) and Zn(II) using the hexadentate chelating ligand, EDTA.
You will be given a ~100 mM standardized solution of EDTA (check the label for exact concentration prior to beginning). You will need to weigh ~0.1 g per metal salt sample. Dissolve the metal salt into 50 mL of DI water. Add 2-3 drops of murexide to your metal. After properly preparing your buret with EDTA, titrate your metal with EDTA. Repeat for a total of 3 titrations per metal.
1. Approximately how much EDTA will you need for each titration assuming the metal-saltsâ masses are accurate?
2. What type of indicator is murexide and what color will its endpoint be?
Post-Lab Questions
1.
a) Using the equations given in the introduction and your titration results, what are the Kn of the EDTA-Copper complex? Show calculations.
b) Using the equations given in the introduction and your titration results, what are the Kn of the EDTA-Zinc complex? Show calculations.
2. What are the corresponding ÎG values for the EDTA-metal complexes? Show your calculations
3. Would copper be considered a hard or soft lewis acid? What about zinc? Describe what makes these metals hard or soft.
4. What trends would you predict for EDTA-metal complex Kn and ÎG values when:
a) going down a row of transition metals of the same oxidation state?
b) of the same transition metal with increasing oxidation state? (For example, Iron can exist as Fe(II), Fe(III), Fe(IV), and higher oxidation states)
5. Discussion (formal report style): Compare and contrast the concepts of Lewis and BrÃ¸nsted-Lowry acids and bases. Support these concepts with your data over the last two weeks and with research. Cite your sources.

CHEM 1320 Lecture Notes - Lecture 26: Pauli Exclusion Principle, Aufbau Principle

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