INTRODUCTION TO CHEMISTRY CHAPTERS 1 AND 2

1.) WHAT IS CHEMISTRY?

The study of matter and the changes that matter undergoes.

2.) WHAT IS A SUBSTANCE?

Also known as a chemical, substance is matter with a definite composition.

3.) WHAT IS MATTER?

Any substance that has mass and takes up space.

4.) DEFINE MASS-

A measure that reflects the amount of matter.

5.) IS WEIGHT THE SAME AS MASS?

No, weight is a measure of the amount of gravitational force acting on matter.

6.) WHAT ARE SOME COMMON BRANCHES OF CHEMISTRY?

Organic BiochemistryInorganic IndustrialPhysical PolymerAnalytical TheoreticalThermochemistry

7.) WHAT IS THE SCIENTIFIC METHOD?

A systematic approach to problem solving used in scientific study.

8.) WHAT ARE THE SEVEN STEPS OF THE SCIENTIFIC METHOD?

1.) state the problem

2.) Gather information on the problem

3.) Form a hypothesis

4.) Perform experiments to test the hypothesis

5) Record and analyze data

6.) State conclusion

7.) Repeat the work

9.) WHAT IS AN EXPERIMENT?

A set of controlled observations that test a hypothesis.

10.) DEFINE HYPOTHESIS.

A tentative explanation for what has been observed.

11.) WHAT IS THE DIFFERENCE BETWEEN QUALITATIVE AND QUANTITATIVE DATA ?

Qualitative data is information that describes color, odor, shape or other physical characteristic. Quantitative data is numerical data.

12.) WHAT IS A VARIABLE?

Something that changes in an experiment.

13.) WHAT IS THE DIFFERENCE BETWEEN THE DEPENDENT AND INDEPENDENT VARIABLE?

The independent variable is changed by the experimenter. The dependent variable(s) are the changes that occur as a result of the changes in the independent variable.

14.) WHAT IS A CONTROL?

A standard for comparison.

15.) WHAT IS THE DIFFERENCE BETWEEN HYPOTHESIS, THEORY AND SCIENTIFIC LAW?

A hypothesis is a tentative explanation about what has been observed.

A theory is an explanation that has been supported by many experiments.

A scientific law describes a relationship in nature, but makes no attempt to explain the relationship.

16.) WHAT TYPE OF RESEARCH SEEKS TO GAIN KNOWLEDGE FOR THE SAKE OF KNOWLEDGE ITSELF?

Pure research

17.) WHAT DO WE CALL RESEARCH THAT IS UNDERTAKEN WITH THE INTENTION OF SOLVING A SPECIFIC PROBLEM?

Applied research

18.) WHAT IS TECHNOLOGY?

Technology is the practical use of scientific information and is the result of both pure and applied research.

19.) WHAT IS THE SI?

The modern metric system.

20.) WHAT ARE THE 7 BASE UNITS OF THE SI?

Dimension unit symbol

Length meter m

Time second s

Mass kilogram kg

Temperature Kelvin K

Amount of

substance mole mol

Electric current ampere A

Luminous intensity candela cd

21.) LIST COMMON METRIC PREFIXES:

Prefix symbol Numerical value in base units

Tera T 1 x 1012 = 1 Tera

Giga G 1 x 109 = 1 Giga

Mega M 1 x 106 = 1 Mega

Kilo K 1 x 103 = 1 Kilo

Hecto H 1 x 102 = 1 hecto

Deka Da 1 x 10 = 1 deka

Base unit

deci d 1 x 10-1 = 1 deci

Continued next slide

21.) LIST COMMON METRIC PREFIXES:

Prefix symbol Numerical value in base units

centi c 1 x 10-2 = 1 centi

milli m 1 x 10-3 = 1 milli

Micro μ 1 x 10-6 = 1 micro

nano n 1 x 10-9 = 1 nano

pico p 1 x 10-12 = 1 pico

21.) LIST COMMON METRIC PREFIXES:

Prefix symbol Numerical value in base units

centi c 1 x 10-2 = 1 centi

milli m 1 x 10-3 = 1 milli

Micro μ 1 x 10-6 = 1 micro

nano n 1 x 10-9 = 1 nano

pico p 1 x 10-12 = 1 pico

22.) WHAT ARE BASE UNITS?

These are the simplest units that can describe a dimension.

23.) WHAT ARE DERIVED UNITS?

Derived units are combinations of more than one base unit.

i.e., speed is m/s

density is g/cm3 or g/mL

24.) WHAT IS DENSITY?

Density is a ratio that compares the mass of an object to its volume. Density can be used to identify a substance.

Density = m/v

25.) WHAT IS THE WATER DISPLACEMENT METHOD?

1 mL = 1 cubic centimeter

For every 1 milliliter of water that is displaced there is 1 cm3 of volume.

26.) WHAT ARE THE THREE TEMPERATURE SCALES CURRENTLY IN USE?

Farenheit, Celsius, Kelvin

27.) CONVERSIONS FOR THE TEMPERATURE SCALES:

a.) To convert from Celsius to Kelvin:

Add 273 ie -39⁰C + 273 = 234K

b.) To convert from Celsius to Fahrenheit:

Tf = 9/5 Tc + 32 ie Tf = 9/5 ( -39) + 32 = -38.2⁰F

c.) To convert from Fahrenheit to Celsius:

Tc = 5/9 (Tf – 32) ie Tc = 5/9 ( -38.2 -32) = -39

28.) SCIENTIFIC NOTATION:

• Used to write extremely small or large #s ( more than 1000 or smaller than 1/1000)

• The # is written as a multiple of two factors: a number between 1 and 10 and ten raised to an exponent. The exponent represents the number of times the decimal is moved.

28.) SCIENTIFIC NOTATION:

• For example

• 7500000 = 7.5 x 106 If the decimal is moved left the exponent is positive. ( If the number is actually a large number the exponent is positive.) • 0.000075 = 7.5 x 10-5 If the decimal is moved right the

exponent is negative. ( If the number is actually a small number the exponent is negative.)

29.) SIMPLE MATH WITH #S WRITTEN IN SCIENTIFIC NOTATION:

* When adding or subtracting the exponents must be the same.• 6 x 103 + 2.5 x 104 6.0 x 103 + 25 x 103 = 31 x 103 or 3.1 x 104

* When you multiply you multiply the numbers and add the exponents• (6 x 102 )(3 x 103) = 18 x 105 or 1.8 x 106

* When you divide you divide the numbers and subtract the exponents• (6 x 103 )÷(2 x 102) = 3 x 10 or 30

30.) WHAT IS DIMENSIONAL ANALYSIS?

• A method used to convert between units while keeping the dimensions conserved.

31.) WHAT IS A CONVERSION FACTOR?

• Conversion factors are used to convert units. A conversion factor is a ratio in which the numerator and the denominator are dimensionally equivalent.

• Ie 1 ft = 12 inches 12 inches/ 1 foot

1 foot / 12 inches

32.) WHAT IS THE DIFFERENCE BETWEEN ACCURACY AND PRECISION?

Accuracy refers to how close a measured value is to an accepted value. Precision refers to how close a series of measurements are to one another.

33.) WHAT IS PERCENT ERROR?

The ratio of error to the accepted value.

34.) WHAT IS THE FORMULA FOR PERCENT ERROR?

% error = actual – accepted

accepted

35.) WHAT IS THE DIFFERENCE BETWEEN AN EXACT NUMBER AND A MEASURED NUMBER?

Exact #s have no uncertainty or error. Measured #s always have uncertainty and/or error.

36.) WHY DO MEASURED NUMBERS ALWAYS CONTAIN A LEVEL OF UNCERTAINTY?

• Error in measuring

• Instrument imperfection

•At some point estimation must be made

37.) WHAT ARE SIGNIFICANT FIGURES?

• The significant figures in any measurement are the digits known with certainty plus one digit that is uncertain.

38) WHAT ARE THE RULES USED TO DETERMINE IF A NUMBER IS SIGNIFICANT?

1.) zeros at the beginning of a number are not significant. i.e. 0.003 has one sig fig

2.) zeros within a number are significant. i.e. 2008 has four sig figs.

3.) zeros at the end of a number after a decimal point are significant. i.e. 10.040 has five sig figs.

4.) When a number is written in scientific notation, all of the #s before the x10n are significant. i.e.

4.00 x 106 has three sig figs.

38) WHAT ARE THE RULES USED TO DETERMINE IF A NUMBER IS SIGNIFICANT?

1.) zeros at the beginning of a number are not significant. i.e. 0.003 has one sig fig

2.) zeros within a number are significant. i.e. 2008 has four sig figs.

3.) zeros at the end of a number after a decimal point are significant. i.e. 10.040 has five sig figs.

4.) When a number is written in scientific notation, all of the #s before the x10n are significant. i.e.

4.00 x 106 has three sig figs.

39.) WHAT IS THE ATLANTIC PACIFIC RULE?

If the decimal point is present begin counting sig figs when you get to the 1st nonzero on the pacific side 0.002510.

If the decimal point is absent begin counting sig figs when you get to the 1st nonzero on the atlantic side. 1040000

40.)RULES FOR REPORTING THE PROPER NUMBER OF SIGNIFICANT DIGITS WHEN SIMPLE MATHEMATICAL OPERATIONS ARE PERFORMED.

a.) When multiplying and dividing, leave as many sig figs in the answer as there are in the # with the least number of sig figs.

2.4 x 3.65 x 8.776 = 76.87776 772 sf 3 sf 4 sf you can report 2 sf

40.)RULES FOR REPORTING THE PROPER NUMBER OF SIGNIFICANT DIGITS WHEN SIMPLE MATHEMATICAL OPERATIONS ARE PERFORMED.

b.) When adding or subtracting, leave the same number of decimal places in the answer as there are in the quantity with the least number of decimal places.

You report to the place value they have in common.

23.1 + 0.54 + 1.456 = 25.096 25.1

The place value all numbers have in common is the tenths place.

40.)RULES FOR REPORTING THE PROPER NUMBER OF SIGNIFICANT DIGITS WHEN SIMPLE MATHEMATICAL OPERATIONS ARE PERFORMED.

Remember when adding or subtracting numbers written in scientific notation you have to first rewrite the numbers so that they have the same exponent.

1.72 x 106 – 1.45 x 105

1.72 x 106 – .145 x 106 = 1.575 x 106 1.58 x 106

41.) ROUNDING RULES:

If the first digit to be dropped is less than 5, leave the preceding digit as it is.

If the first digit to be dropped is more than 5, increase the preceding digit by 1.

25.046 → 25.0

25.096 → 25.1

42.) WHAT ADVANTAGES DO GRAPHS OFFER?

Graphs help patterns to be more obvious and allow predictions to be made.

43.) WHAT ARE SOME COMMON TYPES OF GRAPHS?

Circle, bar and line graphs