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Tomorrow:◦ Start with Concept Check:

A one question quiz through iClicker covering the previous day’s material

Be sure to bring iClicker remote

◦ Before coming to lecture: Read material for Lecture 2:

Chapter 2: pp. 22-44

Scientific Notation◦ Using exponents to express

large and small numbers Converting between standard

notation & scientific notation

Significant Figures◦ How to count “sig figs”

When are zeros significant?

◦ 2 Separate Rules for use in calculations: Multiplication & Division

Addition & Subtraction

CHEM 2: An Introduction to Inorganic Chemistry

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My Expectations & Promises• Students will follow the course

policies and procedures as set out in the Syllabus

• Students will behave and communicate in a safe and professional manner according to the Lab Safety Protocol and Cabrillo Academic Integrity Statement.

• Students will come prepare to lecture and lab, follow a punctual schedule with high standards for achievement, taking responsibility for their education.

• Students will play an active roll in their learning. ASK QUESTIONS! Participate in discussion, seek additional resources and support when necessary.

• I will follow the course policies and approach student assessment objectively and systematically.

• Quizzes, Exams, and Lab Reports will be graded with feedback in a timely manner; grades will be updated frequently on CANVAS.

• Updates to the course schedule and due dates will be listed on the course website and announced in class.

• I will make every effort to make the course interesting, engaging, and challenging to all students enrolled.

• I will facilitate learning and critical thinking through practice problems, applied examples, simulations, and demonstrations.

Chemistry is the study of matter, its interactions and transformations, and the energy associated with those processes.

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CHEMISTRY:What once would have been magic, now is possible

Discovery & Innovation in Chemistry…Fuels development of new technologies

…Provides control of the Atomic scale

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Medical advances would not be possible without Chemistry

With great power comes great responsibility

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The Haber process: a reaction to convert hydrogen and nitrogen gas to ammonia and is carried out on a megaton, industrial scale worldwide. This single

reaction is responsible for the production of both explosives

and chemical fertilizers.

According to MIT Press, the Haber-Bosch process "has been of greater fundamental importance to the modern world than ... the airplane, nuclear energy, space flight, or television. The expansion of the world's population from 1.6 billion people in 1900 to today's seven billion [in 2012] would not have been possible without the [industrial] synthesis of ammonia."

Chemistry has cosmic implicationsOur understanding and perception of the Universe is drastically influenced by chemistry.

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Alchemy is not Science

Alchemy was the earliest attempts to practice

chemistry as a natural philosophy

Alchemists attempted

to change cheap

metals into gold,

through the

transmutation of

elements

Modern Chemistry

Modern Chemistry began with the

work of Antoine Lavoisier in the late

18th Century.

Lavoisier was one of the first chemists

to use quantitative measurements in

chemistry.

Lavoisier was an experimentalist –

testing his theories in the physical

world, rather than simply arguing them

philosophically.

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Results may support hypothesis

or requiremodification

of theory.

Theory createsnew questions

to answer. Hypotheses are

formed.

Experiment

Explanation or Theory

Scientific Method• Lavoisier was one of the first chemists to apply a modern Scientific Method to

his work.

• The scientific method is a cyclical process of experimentation or controlled observation and explanation, hypothesis and theory - to increase understanding about the universe:

Scientific Theory

The scientific method, hypotheses, and experimentation are used to develop theories about the nature of matter.

Theories are not absolute truths.

Theories are the best explanation of observed phenomena.

Theories are continually revised and updated.

A good theory not only explains the observed data, but also accurately predicts what future observations should be.

Many of the theories studied in this course are thought to be very close to the truth, because they have been tested numerous times over years, decades or centuries.

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Scientific Notation A tool for expressing incredibly large or incredibly small

numbers WITHOUT using lots of zeros.

◦ Scientific notation is the combination of a and anexponential of 10 (10x).

In proper scientific notation: The decimal part of the number is always expressed somewhere between 1 n < 10.

Example:

There are approximately 400,000,000,000 stars in our galaxy.

1011 = 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 x 10 = 100,000,000,000

x 1011

A positive exponent (n) means 1 multiplied by 10 n times.

To change a number that is 10 or greater to scientific notation: count how many times you must move the decimal to the left to change the number to something between 1 and less than 10. ◦ The number you counted is the number of factors of 10 you are

dividing out of the number and will be the exponent on the 10 in scientific notation.

Scientific Notation

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Scientific Notation

A negative exponent (-n) means 1 divided by 10 n times.

To change a number less than 1 to scientific notation: count how many times you must move the decimal to the RIGHT to change the number to something between 1 and less than 10. ◦ That number is the number of factors of 10 you are multiplying

into the number and the negative of that number will be the exponent on the 10 in scientific notation.

Examples of Scientific Notation

Express the following numbers in proper scientific notation:

254,000,000,000,000,000 = _______________

0.00009926 = _______________

0.0035 x 108 = _______________

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Examples of Scientific Notation

Express the following numbers in standard notation:

2.87 x 105 = ________________

8.91 x 10-7 = ________________

2.5378 x 103 = ________________

Scientific Notation on the CalculatorTo put an exponential number in your calculator, follow the examples below:

To enter 7.35 x 105, press:[7] [.] [3] [5] [EE] [5]

To enter 4.5 x 102, press:[4] [.] [5] [EE] [+/-] [2]

Note: If your calculator does not have the [EE] key, use the [EXP] key.

To read an exponential off of your calculator, follow these examples:

4.153 04 would be read as 4.153 x 104 or 41,530 8.1 02 would be read as 8.1 x 102 or 0.081

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Various calculator readouts of 8 x 103:

Important note: You must express numbers on paper with proper scientific notation to receive full credit!

Significant Figures

If you divide two numbers, like 1.20 g by 0.07023 mL, your

calculator will tell you that the answer is 17.08671507903

g/mL.

You probably know that you should round the number,

but where, and how do you decide?

The last digit in all measurements is ESTIMATED and determines the number of significant digits in the quantity.

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Uncertainty in Measurement

A digit that must be estimated is uncertain. A

measurement always has some degree of uncertainty.

It is IMPOSSIBLE to get an exact measurement of mass,

distance, time, etc.

Measurement to higher precision A measuring tool with finer markings will make it easier

to take measurements with more significant figures.◦ The measurements will be more precise (reproducible).

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What is the volume in the burette?

Each division is 0.1 mL.

Volume is read at the bottom of the meniscus.

Volume markings increase from top to bottom.

The precision of the Measuring Device influences the Measurement

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Rules for counting Significant Figures:

All non-zero digits are significant.

All zeros between significant digits are significant.

All leading zeros are NOT significant.

Ending zeros are significant if the number contains a

decimal point.

Concept Check:

Converting to Proper Scientific Notation

0.00795 x 10-6

Express the number above in PROPER scientific notation:

A. It already is in proper scientific notation.

B. 7.95 x 10-2

C. 7.95 x 10-3

D. 7.95 x 10-8

E. 7.95 x 10-9

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For multiplication and division, the answer will have the same

number of significant digits as the quantity with the least

number of significant digits.

550 x 321 =

5.1200 x 103 / 0.00205 =

Rules for significant figures in calculations:

Rules for significant figures in calculations:

For addition and subtraction, in numbers that have a decimal place,

the answer to the calculation will have the same number of decimal

places as the quantity with the fewest number of decimal places.

35.290 + 212.1 =

In numbers with no significant decimal places, the number that has

its last significant digit farthest to the left determines where the

answer will be rounded (see example).

768,350,000 – 143,250 =

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Summary of Significant Figure Rules

In ADDITION & SUBTRACTION: The number of significant figures in the starting numbers does NOT matter. It’s the number of

significant decimal places that matters.

In MULTIPLICATION & DIVISION: The final answer is limited by the starting number with the least number of significant figures.

“Sig Figs” - Additional Notes

Exact numbers and counting numbers have an infinite number of significant figures.

In a number in which some ending zeros are significant, but others are not, a bar (above the digit) may be used to indicate the last significant zero.

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Additional Examples: Significant figures in Calculations

(6.2 + 85.60) / 11.558 =

88,000 + 52 =