Basic Principles of Science

What is Science?Accuracy and PrecisionUnits of Measurement

Scientific NotationSignificant Figures

What is Science?The effort to understand how the physical world works.

SCIENCE Astronomy Physics Neurology Chemistry Evolution

NOT SCIENCE Astrology Magic Palm Reading Alchemy Creationism

Science can only be applied to natural events. It cannot be used to support or disprove opinions, beliefs or the truly supernatural.

Because of this, science makes no comment on philosophy, religion, and morality.

What are Chemistry and Physics?

Chemistry is the study of the composition of matter and the changes that matter undergoes.

Physics is the study of the natural world, matter and energy and how the are related.

These two fields are closely related.

Accuracy and Precision

In science, measurements are vital for the advancement of knowledge. Because of this, numbers involved in raw or statistical data must be accurate and precise.

Accuracy is a measure of how close a measurement comes to the actual or true value of whatever is measured.

Precision is a measure of how close a series of measurements are to one another.

Question 1How accurate and/or precise was the dart thrower?

A. Accurate and Precise

B. Inaccurate and Precise

C. Accurate and Imprecise

D. Inaccurate and Imprecise

AnswerHow accurate and/or precise was the dart thrower?

A. Accurate and Precise

B. Inaccurate and Precise

C. Accurate and Imprecise

D. Inaccurate and Imprecise

Question 2How accurate and/or precise was the dart thrower?

A. Accurate and Precise

B. Inaccurate and Precise

C. Accurate and Imprecise

D. Inaccurate and Imprecise

AnswerHow accurate and/or precise was the dart thrower?

A. Accurate and Precise

B. Inaccurate and Precise

C. Accurate and Imprecise

D. Inaccurate and Imprecise

Units of Measurement

In science, measurements are made in an improved version of the metric system; the International System of Units (or SI Units) used and understood by scientists worldwide.SI BASE UNITS

Length (meters “m”) Mass (kilogram “kg”) Time (seconds “s”) Temperature (Kelvin “K”) Amount of Substance (moles “mol”)

SI UnitsConversion Scales

SI Units use a scale of 10 to change between prefixes

Question 3Convert the following measurements.

Sample A. 3,201 km to _____ mSample B. 133.8 ms to _____ s

1. 671 mL to _____ L2. 14 cm to _____ µm3. 5.08 m to _____ nm4. 1.2 kW to _____ mW5. 19,055 kJ to _____ MJ

Question 3Convert the following measurements.

Sample A. 3,201 km to 3,201,000 mSample B. 133.8 ms to 0.1338 s

1. 671 mL to _____ L2. 14 cm to _____ µm3. 5.08 m to _____ nm4. 1.2 kW to _____ mW5. 19,055 kJ to _____ MJ

AnswersConvert the following measurements.

Sample A. 3,201 km to 3,201,000 mSample B. 133.8 ms to 0.1338 s

1. 671 mL to 0.671 L2. 14 cm to 140,000 µm3. 5.08 m to 5,080,000,000 nm4. 1.2 kW to 1,200,000 mW5. 19,055 kJ to 19.055 MJ

Scientific Notation In science (and particularly chemistry) you

encounter very large or very small numbers. Examples: 1 gram of Hydrogen contains approximately

602,000,000,000,000,000,000,000 atoms A single atom of Gold has an approximate mass of

0.000 000 000 000 000 000 000 327 gram For this reason, a shorthand system for writing

sizable numbers is used. Scientific Notation is an expression of numbers

in the form m × 10n where m is between 1 and 10, and n is an integer.

Scientific Notation

To convert numbers into scientific notation, move the decimal until there is only one non-zero number in front of it. The number of moves is equal to the exponent.

Question 4Change these numbers to scientific notation.

Sample A. 3,071,000 to ________Sample B. 0.0014 to ________

1. 6500 to ________2. 0.000 2 to ________3. -137.7 to ________4. 1,200,009 to ________5. 0.000 636 to ________

Question 4Change these numbers to scientific notation.

Sample A. 3,071,000 to 3.071 x 106

Sample B. 0.0014 to 1.4 x 10-3

1. 6500 to ________2. 0.000 2 to ________3. -137.7 to ________4. 1,200,009 to ________5. 0.000 636 to ________

AnswersChange these numbers to scientific notation.

Sample A. 3,071,000 to 3.071 x 106

Sample B. 0.0014 to 1.4 x 10-3

1. 6500 to 6.5 x 103

2. 0.000 2 to 2 x 10-4

3. -137.7 to -1.377 x 102

4. 1,200,009 to 1.200 009 x 106

5. 0.000 636 to 6.36 x 10-4

Significant Figures

When measuring, the exactness of your measurements are very important. To determine which figures are important, we use the five rules of significant figures.

All the digits that can be known precisely in a measurement are significant figures.

Significant figures must be determined before converting numbers into scientific notation.

Rules of Significant Figures

1. All non-zero numbers (1-9) ARE significant.

2. All zeros between non-zeros ARE significant.Example: 1001 has four significant figures.

3. Leftmost zeros in front of non-zeros ARE NOT.Example: 0.000032 has two significant figures.

Rules of Significant Figures

4. Zeros at the end of a number and to the right of a decimal point ARE significant.Example: 450.0 and 1.020 have four significant

figures.NOTE – the number MUST have a decimal point

5. Zeros at the rightmost end of a number and are left of an 'understood decimal point' ARE NOT.Example: 1 000 and 60 000 have one significant

figure.

PLEASE NOTE THE DIFFERENCE

Question 5How many significant figures are in these numbers?

Sample A. 3002.0 has ________Sample B. 0.00 670 has ________

1. 223 has ________2. 1 000 000.0 has ________3. 0.05070 has ________4. 300. has ________5. 0.0 074 010 has ________

Question 5How many significant figures are in these numbers?

Sample A. 3002.0 has fiveSample B. 0.00 670 has three

1. 223 has ________2. 1 000 000.0 has ________3. 0.05070 has ________4. 300. has ________5. 0.0 074 010 has ________

AnswersHow many significant figures are in these numbers?

Sample A. 3002.0 has fiveSample B. 0.00 670 has three

1. 223 has three2. 1 000 000.0 has eight3. 0.05070 has four4. 300. has three5. 0.0 074 010 has five

Multiplying in Scientific Notation

When multiplying numbers in scientific notation, the first two integers multiplied as normal.

The exponents are added NOT MULTIPLIED. If the number at the front becomes larger than

10, move the decimal to the left and add one to the exponent.

The significant figures of your answer may not be greater than the SMALLEST number of significant figures in the factors.

Example(2.1 x 103) x (5.2 x 105)

Multiplying in Scientific Notation

(2.1 x 103) x (5.2 x 105)

multiply the first numbers 2.1 x 5.2 = 10.92adjust for significant figures 10.92 ~ 11add the exponents 3 + 5 = 8put together 11 x 108

adjust the first number 1.1 x 109

Dividing in Scientific Notation

When Dividing numbers in scientific notation, the first two integers divided as normal.

The exponents are subtracted NOT DIVIDED. If the number at the front becomes smaller than

1, move the decimal to the right and subtract one from the exponent.

The significant figures of your answer may not be greater than the SMALLEST number of significant figures in the quotients.

Example(3.5 x 106) / (5.6 x 102)

Dividing in Scientific Notation

(3.5 x 106) / (5.6 x 102)

divide the first numbers 3.5 / 5.6 = 0.625adjust for significant figures 0.625 ~ .63subtract the exponents 6 – 2 = 4put together .63 x 104

adjust the first number 6.3 x 103

CLASSWORKCalculate the answers to these problems

1) (4 x 106) / (2 x 102)

2) (1.5 x 102) x (4 x 107)

3) (3.7 x 10-3) / (-1.9 x 10-8)

4) (4.71 x 10-3) x ( 5.89 x 103)