CHEM125B Fall, 2006

Exam # 3 Dunnivant

Name (PRINTED) ____________________________________

There are 100 points.

The honor statement must be signed in order for your exam to be graded.

Closed book, closed Internet, closed notes, closed neighbor!

I have neither given nor received aid on this exam.

Signature ________________________

NOTES:

-Show all work for partial credit.

-Significant figures and units will be graded throughout the exam.

h = 6.63 x 10^-34 J•s

Avg.’s # = 6.022 x 10²³ anythings/mol

c = 2.998 x 10⁸ m/s

R = 1.097x10⁷ m^-1

E = hn

c = ln

DE = E_final - E_initial

E = C (1/n²)

C = R h c

1. (10 pts) List the complete spectrum of electromagnetic radiation from high energy to low energy. Beside each type of radiation, explain how it interacts with an atom or molecule.

HIGH ENERGY

LOW ENERGY

2. (10 pts) An electron in a hydrogen atom goes from a principal energy state of 1 to an excited state of 4.

Calculate the energy involved in this transition: __________________________

Is the change in energy state endothermic or exothermic? ___________________

Calculate the wavelength (in nm) of a photon emitted or absorbed by this transition: ________________

Is the photon emitted or absorbed? ____________

3. (10 pts) Draw and explain the experiment that first illustrated Plank’s quantization of photons (light).

4. (5 pts) Both the Bohr and Schrodinger explanation of electron transitions in an atom use an “n” level to describe the energy change. How did each scientist come up with “n”?

5. (5 pts) What do each of the quantum numbers mean/represent?

n

l

m_l

m_s

6. (5 pts) Explain why atomic size decreases as you go from left to right in the Periodic Table.

7. (5 pts) Explain the difference between an ionic and a covalent bond.

Give the chemical formula of an example of each type of bond.

8. (5 pts) What is the difference between a core and a valence electron?

9. (5 pts) Give the complete spectroscopic notation for P.

10. (5 pts each) Draw Lewis dot structures for the following. Also draw any resonance structures that can exist.

Nitrate

Electron domain name: __________

Molecular domain name: __________

Type of hybridization on N: __________

Ozone (O₃)

Electron domain name: __________

Molecular domain name: __________

Type of hybridization on the central O: __________

SF₆

Electron domain name: __________

Molecular domain name: __________

Type of hybridization on S: __________

11. (10 pts) What two qualities must a chemical have to bioconcentrate in biota.

_____________________

_____________________

Explain how bioconcentration (biomagnification) occurs for some pollutants.

12. (2.5 pts each) What is the purpose of Lewis dot structures?

What is the purpose of VSEPR theory?

What is the purpose of Valance Bond theory?

What do we mean by hybridization of bonds?

What is the purpose of the molecular orbital theory

What is the meaning of life?