CHEM-101

Powerpoints from week ending

1/20/2012

An Introduction to Chemistry 101

Spring 2012

Instructor: Elizabeth Dillon Email: elizabethadillon@comcast.net Office Hours: by appointment Text: Chemistry, by Raymond Chang, 10th Edition, 2007, McGraw-Hill, Inc. Student Solutions Manual by Brandon J. CruickshankSupplies you will need: The texts. A hand held calculator with square roots, log, ln and exponential numbers. A notebook for classThe course in a nutshell: General Chemistry I is an intensive courseIt is intended to give students a broad survey of the field of chemistry and to help develop quantitative skills, familiarity with molecular structure and the periodic table for the science student wishing on transferring to a four-year college. Subjects covered include: atomic structure, chemical bonding acids and bases, gasses, solids and liquids and properties of solutions.

CHEM-101-006RLSpring 2012

Instructor’s addendum to the Course Syllabus

You must take responsibility for your own learning.  Your job as a student is to learn the concepts!  An active, responsible learner seeks not to limit what they should know, but embraces and conceptually consumes as much material as possible.  Knowledge is power; arm your self with it!

The Students Role in the Course

Instructors Role

As your instructor, I am here to guide your development and suggest what skills and knowledge might be useful,--- much like a sports team coach. The game’s outcome depends upon your skill, your level of effort and your dedication to the course.

Achieving SuccessSuccess in this class is directly proportional to the time you put into attending lecture and lab, working problems, and reading your notes and textbook. Working problems and reading through notes and the textbook every night will greatly aid in preparation for tests and quizzes.

Practice ProblemsProblems: Representative problems from each chapter can be found in the Departmental Syllabus. Doing these problems is an important part of the learning process because, what each problem is really asking is; do you genuinely understand the concept? If you can do these problems then you should understand the material. But, if you do not, at least you have a built-in indicator that you should take further steps to grasp the concept or concepts that you thought you understood but really did not.

Because you must take responsibility for your own learning, the problems are not to be handed in. They are a means for you to monitor your understanding of the material, your ability to give clear and lucid answers, and to apply all you have learned in a logical and rational manner.

Class InformationClass meetings: Wednesday and Friday mornings 8:00am- 9:45am in MAS 026. In accordance with the Brookdale Student Conduct Code you have the responsibility to conduct yourself in a mature manner at all times so as to ensure an environment conducive to learning. You are expected to attend class regularly and to arrive on time. Attendance will be taken by passing a roll sheet around. If you are late, you are expected to enter the classroom silently, take the first available seat and wait until after class to sign the roll sheet. Cell Phone Policy: When arriving to class please turn off your cell phone or put it in vibrate mode. You should place all your belongings on the floor and not on the desk when taking the exam.

GradingIn recent years, students have become increasingly focused on obtaining a certain grade in the course. Please remember, GRADES ARE NOT GIVEN BY THE INSTRUCTOR, THEY ARE EARNED BY THE STUDENT and are directly related to the student’s level of understanding of the material. Focusing on the grade before the learning is, shall we say, “putting the cart before the horse”. Just as the horse cannot pull a cart placed in front of it, the student who focuses on his grade in lieu of simply mastering the material will not achieve the desired result. It is therefore best to focus on learning and understanding the material rather than obtaining a certain grade.When you master the material the grade then follows!

Grading, continued…

Students are encouraged to read the popular press (newspapers and magazines) and find, read, and study articles related to chemistry. Your lecture grade will be based on your performance on four one hour examinations, worth 100 points each, a minimum of 5 quizzes of which one will be dropped and one critique ( 100pts).Exams are given during the last hour of class. Quizzes are given during the first 15 minutes of class or are take-home. There are no make-up quizzes/exams. If you are absent (or are late for class) and miss an exam or a pop quiz, a grade of 0 will be assigned.

I use the point system of grading. You can calculate your lecture grade at any time by dividing the points you have earned over the total possible points to date and multiplying by 100.

Grades• Your course grade is determined as follows: Lecture 80% Lab 20%Grades: A = 92 – 100(Excellent Understanding of Material) A- = 89 - 91.99(Very Good Plus Understanding of Material B+ = 86 – 88.99(Very Good Understanding of Material) B = 82 – 85.99(Good Understanding of Material) B- = 79 – 81.99(Satisfactory Plus Plus Understanding of Material) C+ = 76

– 78.99(Satisfactory Plus Understanding of Material) C = 70 – 75.99(Satisfactory Understanding of Material) D = 65 - 69.99 (Marginal Understanding of the Material F= 65 and below (Unsatisfactory Understanding of the Material)

• The CHEM-101 laboratory must be taken concurrently with the lecture. Laboratory grades from a previous semester will not be accepted.

• Note: You have to pass the lab to pass the course.

Begging for GradesAs indicated above, if your average is at least 92, you have an A; at least 86, a B+; at least 82, a B; at least 76, a C+ at least 70 a C, at least 65 a D; and below 65 is an F. These grade cutoffs are absolute -- for example, a 69.99 is a D, not a C. When transforming total scores to letter grades, "close" does not count.

Please do not embarrass yourself and me by begging for extra credit after final grades have been awarded. FINAL GRADES are ………. FINAL. Please remember that I grade your performance, not your personal worth.

Most professors receive numerous "begging for points" emails shortly after final grades are posted.  When I receive such emails I simply discard them without replying to them.  This may seem rude, but it is rude to beg for points, especially after I have clearly explained that such behavior is inappropriate and ineffective. 

Chapter 1

Chemistry The Study of Change

Chemistry is Important---

• It lies at the heart of :• Our efforts to produce new materials to make

our lives easier and safer• Our efforts to produce new sources of energy

that are abundant and non-polluting • Our efforts to understand disease that

threatens us and our food supply

Chemistry is good for you….

• Even if your eventual career does not require daily use of chemical principles

• Your life will be greatly influenced by your time in chemistry class

• You will become a better problem solver

Chemistry has a reputation for being tough.

• Chemistry deals with rather complicated systems that require some effort to figure out

• This might seem like a disadvantage…..but can be turned into an advantage!

•Recruiters for all types of companies maintain that the first thing that they look for in a prospective employee is the ability to solve problems.

•We will spend a good deal of time solvingvarious types of problems using a systematic logical approach that will serve you well in solving any kind of problem in any field.

With this in mind, let us begin our……

Study of Chemistry

• Chemistry is defined as the science that deals with the materials of the universe and the changes that these materials undergo

• More specifically chemistry deals with the composition, structure, properties and reactions of matter, especially of atomic and molecular systems.

• Chemistry is often called the “central science” because most of the phenomena that occur in the world around us involve

chemical changes

Solving Problems using a Scientific Approach

• One of the most important things we do on a daily basis is to solve problems

• Most decisions you make every day can be described as solving problems

Everyday Problems

• It’s 8:30 am Wednesday, which is the best way to drive to school to avoid traffic congestion?

• You have 2 tests on Monday, should you divide your study time equally or allot more time to one than the other?

• Your car stalls at a busy intersection and your little brother is with you. What should you do next?

• What process do we use to solve everyday problems?

• Although you have probably not thought about it before, there are several steps that almost everyone uses to solve problems

Solving Everyday Problems

• 1. Recognize the problem and state it clearly. Some information becomes known or something happens that requires action.

• 2. Propose possible solutions to the problem or possible explanations for the observation.

• 3. Decide which of the solutions is best or decide whether the explanation proposed is reasonable.

---To do this we search our memory for any pertinent information or we seek new information.

****Scientists (chemists) use the same procedure to study what happens in the world around us.

Remember………….

• Science is not simply a set of facts. It is also a plan of action a procedure for processing and understanding certain types of information.

• Science is observation, identification, description, experimental investigation, and theoretical explanation of natural phenomena.

• The process that lies at the center of scientific inquiry is the Scientific Method.

• The Scientific Method is not much different from solving everyday problems

Solving Everyday Problems and The Scientific Method

• 1. Recognize the problem and state it clearly. Some information becomes known or something happens that requires action. In science this is called an observation.

• 2. Propose possible solutions to the problem or possible explanations for the observation. In science this is called a hypothesis

• 3. Decide which of the solutions is best or decide whether the explanation proposed is reasonable. In science we perform an experiment

Scientific Method

Involves 3 Steps: 1. Make observations: Observations may be qualitative or quantitative

2. Formulate Hypotheses: A hypothesis is a possible explanation for an observation.

3. Perform experiments: An experiment is something we do to test the hypothesis.

Qualitative: do not involve a numberie. The sky is blue.Water is a liquid

Quantitative: involve a numberand a unit. Are called measurements.ie. Water boils at 100oC.This book weighs 4.5 lbs.

Through experiment we gather new information that allows us to decidewhether the hypothesis is supported by the new information we learned in the experiment.

Scientific Method

• Experiments always produce new observations and bring us back to the beginning of the process again

• To explain the behavior of a given part of nature we repeat these steps many times

• Gradually we accumulate the knowledge necessary to understand what is going on

• Once we have a set of hypotheses that agree with our various observations we assemble them into a theory that is often called a model

The Scientifc Method

A Theory

• Is a set of tested hypothesis that give an overall explanation of some part of nature

• It is an interpretation ….a possible explanation of why nature behaves in a particular way

***It is important to differentiate between an observation and theory.

Remember: -an observation is something that is witnessed and can be recorded-A theory is an interpretation (possible explanation) of why

nature behaves in a particular way

Scientists Never, Never, Ever…

• Stop asking questions just because they have devised a theory that seems to account satisfactorily for some aspect of natural behavior

ie. The discussion can not be out on the Theory of Global Warming!!

Scientists Always…..• Continue doing experiments to refine their theories• Theories (Models) are human inventions • they represent our attempts to explain observed

natural behavior in terms of our human experiences• We must continue to do experiments and refine our

theories to be consistent with new knowledge• Theories are refined by making a prediction and then

doing an experiment to see if the results bear out this prediction

observation

Hypothesis

Experiment

Theory

Prediction

Experiment

Theory Modified asNeeded

Laws• As we observe nature we often see that the same

observation applies to many different systems• Generally observed behavior is formulated into a

statement called natural lawie. Law of conservation of Mass- total weights of

materials is not affected by a chemical change Law- summary of observed (measurable) behavior ….it

tells what happensTheory- is an explanation of a behavior….it is our

attempt to explain why it happens

observation

Hypothesis

Experiment

Theory

Prediction

Experiment

Natural Law

Theory Modified asNeeded

Summary of the Scientific Method

Important Points to Remember

• Science does not always progress smoothly and efficiently

• Scientists are human: - they have prejudices - they misinterpret data - they can become emotionally attached to their theories and lose objectivity -they play politics• Science is affected by profit motives, budgets, fads,

wars and religious beliefsThe Scientific Method is only as effective as the

humans using it.

Matter• The “stuff” of which the universe is composed• Matter has 2 characteristics:1. it has mass2. it occupies space• Mass has a variety of forms: the air we breathe, gas we put

into our cars, the chair you sit in, the sandwich you eat, tissues in your brain that allow you to comprehend this material

• Matter appears to be continuous and unbroken.─ Matter is actually discontinuous. It is made up of tiny particles

called atoms• The various forms of matter are called states

1.51.5

Physical StatesPhysical Statesof Matterof Matter

3 States of Matter

1. Solid ie. Ice cube, diamond , iron bar

2. Liquid ie. Gasoline, water, alcohol, blood3. Gaseous ie. Hydrogen, helium, oxygen and the air we

breathe

SOLIDS

Shape • Definite - does not change. It is independent of its container.

Volume • Definite

Particles • Particles are close together. Theycling rigidly to each other.

Compressibility • Very slight–less than liquidsand gases.

A solid can be either crystalline or amorphous. Which one it is depends on the internal arrangement of the particles that constitute the solid.

Amorphous: without shape or form.

LIQUIDS

• Not definite - assumes the shape of its container.

Volume • DefiniteParticles • Particles are close together.

• Particles are held together by strong attractive forces. They stick firmly but not rigidly to each other.

• They can move freely throughout the volume of the liquid.

Shape

Compressibility • Very slight–greater than solids,less than gases.

GASESShape • No fixed shape.

Volume • Indefinite.

Particles • Particles are far apart compared to liquids and solids.

• Particles move independently of each other.

GASES

Compressibility • The actual volume of the gas particles is small compared to the volume of space occupied by the gas.– Because of this a gas can be

compressed into a very small volume or expanded almost indefinitely.

1.41.4

Classifying MatterClassifying Matter

Matter refers to all of the materials that make up the universe.

***Both Homogeneous and Heterogeneous mixtures can be separated by physical means into pure substances*** Compounds can be changed into elements by chemical means

Pure Substances

■ Matter that has a fixed composition and distinct properties.

- always the same composition - pure substances are always homogeneous

Examples

ammonia, water, and oxygen.

Elements

• cannot be broken down into other substances by chemical means

• can be found in the free state or the combined state with other elements

ExamplesFe, Al, O2, H2

Compounds

• substance composed of elements that can be broken down into those elements by chemical means

• always have the same combination of atoms

ExamplesH2O, FeS

Homogenous Matter

• Matter that is uniform in appearance and with uniform properties throughout

ice, soda, pure gold

Examples

Heterogeneous Matter

• Matter with two or more physically distinct phases present.

Examples

ice and water, wood, blood

Homogeneous

Heterogeneous

Phase

• A homogenous part of a system separated from other parts by physical boundaries.

In an ice water mixture, ice is the solid phase and water is the liquid phase.

Examples

Mixtures

• Matter containing 2 or more substances that are present in variable amounts.

• Mixtures are variable in composition. They can be homogeneous or heterogeneous

ExamplesWine, coffee, wood

Homogeneous Mixture (Solution)

• A homogeneous mixture of 2 or more substances.

• It has one phase.

ExamplesSugar and water. Before the sugar and water are mixed, each is a separate phase. After mixing the sugar is evenly dispersed throughout the volume of the water. Also air, salt water and brass.

Heterogeneous Mixture

■ A heterogeneous mixture consists of 2 or more phases.

• Contains regions that have different properties

ExamplesChocolate chip cookie, sand water, mud water or sugar and fine white sand. The amount of sugar relative to sand can be varied. The sugar and sand each retain their own properties.

Heterogeneous Mixture of One Substance

■ A pure substance can exist as different phases in a heterogeneous system.

Ice floating in water consists of two phases and one substance. Ice is one phase, and water is the other phase. The substance in both cases is the same.

Examples

SystemThe body of matter under consideration.

Examples

In an ice water mixture, ice is the solid phase and water is the liquid phase. The system is the ice and water together.

Physical Methods of Separation

• Distillation- means of separating 2 liquids or a liquid from a dissolved solid

- uses differences in boiling points

-involves vaporization and condensation of the liquid/liquids

• Filtration- used to separate a liquid from an insoluble solid

Measurements in Chemistry

• As you learned in our discussion on the Scientific Method, observations can be qualitative or quantitative

• Quantitative observations are called measurements• Measurements have two parts: 1. a number 2. a unitboth parts are necessary to make a measurement

meaningful

I saw a bug 5 long!

• The above statement is meaningless as is. • 5 what?• If it is 5 mm it is small• If it is 5 cm it is large• If it is 5m run for cover!

Unit is important, because it tells us the scale being used

Form of a Measurement

70.0 kilograms = 154 pounds

numerical value

unit

Formulating some questions

• How reliable are the numbers in a measurement?• How reliable is a measurement that results from

mathematical operations?• How can we conveniently express very large and very

small numbers?• What units do we need to express dimensions, mass

and volume?• How can we convert between related units of

measurement?

Scientific Notation

• The numbers associated with scientific measurements are often very large or very small

6022000000000000000000000.00000000000000000000625

• Very large and very small numbers like these are awkward and difficult to work with.

Scientific Notation

• Scientific Notation is a method for making very large or very small numbers more compact and easier to write

6.022 x 1023

6.25 x 10-21

Scientific Notation

• Expresses a number as a product of a number between 1 and 10 and the appropriate power of 10

• To determine the power of 10: - start with the number being represented and

count the number of decimal places the decimal point must be moved to obtain a number between 1 and 10

- when the decimal is moved to the left the exponent of 10 is positive

- when the decimal is moved to the right the exponent of 10 is negative

Write 6419 in scientific notation.

64196419.641.9x10164.19x1026.419 x 103

decimal after first nonzero digit

power of 10

Write 0.000654 in scientific notation.

0.0006540.00654 x 10-10.0654 x 10-20.654 x 10-3 6.54 x 10-4

decimal after first nonzero digit

power of 10

Scientific notation and calculators

• We write scientific notation as6.03 1023

• Calculators handle scientific notation by only inputting the exponent, using an EXP or EE key

• You should enter the mantissa (number between 1 and 10) as you would for a regular number, then press EXP or EE, then enter the exponent

Measurements

• Experiments are performed.• Measurements are made.

Features of Measured Quantities

• When we measure a number, there are physical constraints to the measurement

• Instruments and scientists are not perfect, so the measurement is not perfect (i. e., it has error)

• The error in the measurement is related to the accuracy and the precision of the measurement

Accuracy and Precision

• Accuracy – how close the measurement is to the “true” value (of course we have to know what the “true” value is)

• Precision - the degree to which the measurement is reproducible

• We express precision through how we write the number using significant digits

Accuracy and Precision

Significant digits or figures

• Significant digit – a digit that is either reliably known or estimated

• We write numbers with digits, and assume that the last digit is uncertain

• For example, in the number 1.23, there are three significant digits, and we assume that the last digit, the 3, is uncertain

Significant Figures

• The number of digits that are known plus one estimated digit are considered significant in a measured quantity

estimated5.16143

known

Reading a ThermometerReading a Thermometer

Temperature is estimated to be 21.2oC. The last 2 is uncertain.

The temperature 21.2oC is expressed to 3 significant figures.

Temperature is estimated to be 22.0oC. The last 0 is uncertain.

The temperature 22.0oC is expressed to 3 significant figures.

Temperature is estimated to be 22.11oC. The last 1 is uncertain.

The temperature 22.11oC is expressed to 4 significant figures.