WEEK 1: 9 JAN THRU 15 JAN; LECTURES 1-4

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1 Learning objectives Basics: No recitation problems. Handled in ALEKs and week one homework problems but will be part of quiz. Measurement o Metric units, Unit Conversion within metric o Significant figures, use of rounding in calculations (accuracy, precision) States of matter (gas, liquid, solid) & Density Properties of matter (chemical, physical, intensive, extensive) Definition of elements, compounds, mixtures Basic atomic structure Understand the basic Structure of atom (protons, neutrons, electrons in atoms and ions) Given an atomic symbol (neutral or ion), be able to determine the number of protons, neutrons and electrons Know the definition of Isotope, be able to give examples, recognize isotopes. Be able to use average atomic mass and isotope ratios for an element to solve problems. Know the definition of Atomic mass, be able to use it to get molar mass of compounds or to find isotope ratios. Know definition of mole (Mole = N A = ). Be able to use it to make connections between experimental properties (macroscopic ) and molecular level properties. Introduction to Energy Difference between kinetic and potential energy (can you make up your own examples?) Know units of energy and order of magnitude of different kinds of energies (photon energy, etc.) Know what is meant by electrostatic energy. Be able to use Coulomb's Law to describe the interaction of charged particles. Be watching for electronic energy, i.e., the energy of an electron. What is the First Law of Thermodynamics? Watch for how the potential energy of electrons gets converted to kinetic energy (a photon). What is meant by the system? The surroundings? What does the sign of energy mean? o + means energy (= q + w) into the system (endothermic = q into system) o means energy (= q + w) out of the system (exothermic = q out of the system) Notice State functions (like P, T V) as we encounter them and keep the definition of state function in mind. Why is it useful to know that these are state functions? Energy: Light as energy Describe the wave nature of light, wavelength, and frequency using the equation c = λν What is meant by the particle nature of light? Calculate the energy of a photon using the equation E = hν Be familiar with types of radiation and their relative energies in the electromagnetic spectrum (Which have long wavelengths? Which have short? Which have high energy, which have low?) Describe the relationship between color of visible light and its relative energy in the electromagnetic spectrum Describe the relationship between wavelength and energy of a photon using the equation E = hc/λ Perform calculations involving the total energy of multiple photons using the equation E T = n(hc/λ) Week 1 CHEM 110 Student Packet - Spring

2 Homework Problems Due: Thurs. Jan. 17 before recitation 1A. What is the change in internal energy for each the following situations? The grey box represents the system in C and D and the arrows indicate the direction of the change I. q = 3.4 J into system and w = 6.3 J done on the system II. q = 6.5 J out of the system and w = 2.2 J done by the system III. IV. q = 4.7 J w = 1.9 J q = 3.4 J w = 6.3 J 1B. Which of these represents an exothermic process? 2A. The following pictures show charged particles separated by a distance d. Which of the following have attractive interactions? Which have repulsive interactions? I II III 2B. Assuming the distance d is the same for all of these, rank them in order of increasing electrostatic potential energy. 3. Rank the interactions between the particles shown below in order of increasing electrostatic potential energy. I. d II. 1 2 d III. 2d Week 1 CHEM 110 Student Packet - Spring

3 4. Chlorine exists primarily as 37 Cl and 35 Cl and has an average atomic weight of The abundance of Cl with atomic weight of 35 is A. 23% B. 91% C. 77% D. 45% E. None of the above is within 10% of the correct answer 5. How many protons, neutrons and electrons are present in O? A. p=8, n=9, e=10 B. p=8, n=9, e=8 C. p=8, n=9, e=6 D. p=9, n=8, e=11 E. p=9, n=8, e=9 6. X and Y are two species, each consisting of one nucleus and a number of electrons. The two species are found to contain the same number of protons, the same number of neutrons, and different numbers of electrons. Which of the following statements about X and Y is correct? A. X and Y are both neutral atoms. B. X and Y are isotopes of one another. C. The two have different atomic numbers. D. At least one of the species is an ion. E. There is no correct answer above since A D are all incorrect. 7. A radio station broadcasts on a frequency of 99.5 kilocycles/s. What is the wavelength of this radiation in km? A km B km C What is the energy possessed by one mole of x ray photons if the wavelength of the x ray is m? A J B J C J D J E J 9. Green light of wavelength 516 nm is absorbed by an atomic gas. What is the energy difference between the two quantum states involved in the transition? A J B J C J D J E J 10. Which photon has an energy that is greater than the energy of a blue photon? A. microwave photon B. radio photon C. green photon D. infrared photon E. ultraviolet photon 11. A He-Ne laser (λ = 633nm) is used to heat up a sample. How many photons are needed to transfer 12 J of heat to the sample? A B. 12,000 C D E Week 1 CHEM 110 Student Packet - Spring

4 Recitation Worksheet 1. In the lab a substance is studied and the following observations are made. At room temperature (20 C) the substance has the following properties: 1. It is a solid that is shiny and silver in color. 2. It has a density of g/cc 3. It is malleable (it can be pounded into a flat sheet.) 4. It is ductile (it can be pulled into a thin wire). 5. It is a good electrical conductor. The substance is subjected to some further experiments and these additional observations are made. 6. It melts at 649 C 7. It boils at 1105 C. 8. It burns in air, glowing with an intense white light. 9. It reacts with bromine to give a brittle white solid Which of these characteristics are physical properties, and which are chemical properties? 2A. How many protons, neutrons and electrons are present in 235 U 4+?What does the 4+ indicate? What does the number 235 indicate? 2B. Which of these species has 45 neutrons? A. 80 Kr B. 80 Br C. 78 Se D. 79 Kr E. 80 Rb 3. Natural uranium mined from the Earth contains the isotopes uranium-238, uranium-235 and uranium-234. The majority ( %) of all the atoms in natural uranium are uranium-238. Most of the remaining atoms (0.72%) are uranium-235, and a slight trace (0.0055%) are uranium-234. Determine the average atomic weight of uranium. 4. Which of the following processes has a positive value for E and which are endothermic? i. A system absorbs 50 kj of heat from the surroundings and does 30 kj of work on the surroundings. E = q + w Draw pictures using a box to represent the system and use arrows to show if energy is going into the system or out of the system Week 1 CHEM 110 Student Packet - Spring

5 5. Rank these in order of increasing electrostatic potential energy. I an electron that is 2.8 nm from a +2 cation II an electron that is 2.8 nm from a 2 anion III an electron that is 2.8 nm from a proton A. I < III < II B. I = II < III C. II < III < I D. II < I < III E. III < II = I Hint: draw a picture to help you with this What is the frequency of the wave shown below assuming it is light (electromagnetic radiation)? What is the frequency of light with an energy of 124 kj/mol? 8. A particular microwave photon has a wavelength of 0.01 m, a photon of green visible light has a wavelength of 520 nm and a photon of gamma radiation has a wavelength of 8 pm. Rank these forms of electromagnetic radiation in order of increasing energy and frequency. Frequency (ν): Energy (E): What general trend do we see? 9. Which one of the following photons is higher in energy than a green photon? A. Microwave photon B. ultra-violet photon C. Red photon D. Radio frequency photon Challenge question: 10. An Argon laser gives off pulses of green light (wavelength = 514 nm). If a single pulse from the laser has a total energy of 10 mj how many photons are in the pulse? Week 1 CHEM 110 Student Packet - Spring