Chapter 1

Science Skills

Science and Technology

• “Science” derives from Latin scientia, meaning “knowledge”

• Science: a system of knowledge and the methods used to find that knowledge.

• Technology: the use of knowledge to solve practical problems.

• Difference: Science expands knowledge; technology applies knowledge.

Physical Science

• Science: divided into social and natural

• Natural science: 3 branches—physical, Earth and space, life

• Physical science: a branch of natural science that focuses on non-living things

• 2 main areas: chemistry and physics

Chemistry and Physics

• Chemistry: the study of the composition, structure, properties, and reactions of matter

• Physics: the study of matter and energy and the interactions between the two through forces and motion

Earth Sciences

• Geology: the study of the origin, history, and structure of earth.

• Astronomy: the study of the universe beyond Earth, including the sun, moon, planets, and stars

Life Sciences

• Biology: the study of living things

• Bios: Greek for “life”

• -ology: “study of”

Scientific Method

• Definition: an organized plan for gathering, organizing, and communicating information.

• Goal: to solve a problem or to better understand an observed event

Steps in the Scientific Method(1) Make observations

(2) Ask a question

(3) Form a hypothesis

(4) Test the hypothesis/collect data

(5) Analyze data

(6) Conclusions

Definitions

• Observation: information obtained through the senses

• Hypothesis: a proposed answer to a question

• Scientific theory: a well-tested explanation for a set of observations or experimental results

• Note: Theories are never proved• Scientific law: a statement that

summarizes a pattern found in nature

Models

• Model: a representation of an object or event

• Models make it easier to understand things that might be too difficult to observe directly

Scientific Notation

• Scientific notation: a way of expressing a value as the product of a number between 1 and 10 and a power of 10.

Example 1

• Example: speed of light

• Numeric value: 300,000,000 m/s

• In scientific notation: 3.0 x 108 m/s

Example 2

• Example: speed of a snail

• Numeric value: .00086 m/s

• In scientific notation: 8.6 x 10-4 m/s

• Note: If the number you begin with is less than 1, your exponent will be negative.

Multiplying in Scientific Notation• Rule: Multiply the numbers that appear

before the multiplication signs and ADD the exponents.

• (3.0 x 108m/s) x (5.0 x 102s)• Step 1: Multiply: 3 x 5 = 15• Step 2: Add exponents: 108 + 102 =

1010

• “Raw” answer: 15 x 1010 m• Final answer: 1.5 x 1011m

Dividing in Scientific Notation• Rule: Divide the numbers that appear

before the exponential terms and SUBTRACT the exponents.

• 1.5 x 1011m

3.0 x 108 m/s• Step 1: Divide numbers 1.5/3 = 0.5• Step 2: Subtract exponents11-8 = 3• Raw answer: 0.5 x 103s• Final answer: 5.0 x 102s

Practice Problem # 1

• (7.6 x 10-4 m) x (1.5 x 107 m) = ?• Step 1: Multiply the numbers that

appear before the multiplication signs.

• 7.6 x 1.5 = 11.4• Step 2: Add the exponents. • 10-4 + 107 = 103 • Raw answer: 11.4 x 103 m2

• Final answer: 1.14 x 104 m2

Practice Problem # 2

• 0.00053 / 29• Step 1: Convert to scientific notation• 5.3 x 10-4 / 2.9 x 101 • Step 2: Divide the numbers that appear

before the exponential terms • 5.3 / 2.9 = 1.8• Step 3: Subtract the exponents• 10-4 – 101 = 10-5

• Answer: 1.8 x 10-5

Bell-ringer

• What is a Kelvin?

Units of Measurement

• For a measurement to make sense, it requires both a number and a unit.

• Scientists do not measure in inches, feet, and degrees Fahrenheit.

• Scientists use a set of measuring units called SI

SI Definitions

• Length: the straight-line distance between two points

• Mass: the quantity of matter in an object or sample

• Volume: the amount of space taken up by an object

• Density: the ratio of an object’s mass to its volume (D = m/v)

SI Base Units

• Length meter (m)

• Mass kilogram (kg)

• Temperature Kelvin (K)

• Time second (s)

• Amount of substance mole

Significant Figures

• Significant figures: all the digits that are known in a measurement, plus the last digit that is estimated.

• The fewer the significant figures, the less precise the measurement is.

• The precision of calculated answer is limited by the least precise measurement used in the calculation.

Significant Figure Problem

• A piece of iron weighs 34.73 grams. Its volume is 4.42 cubic centimeters.

• (a) What is its density? • Answer: D = m/v = 34.73/4.42• (b) How many significant figures should

the answer contain? • Answer: 3• Why: Because the least precise

measurement (volume) has 3 significant figures.

• Final answer: 7.86 g/cm3

Measuring Temperature

• Thermometer: an instrument that measures temperature.

• Fahrenheit: water freezes at 32o and boils at 212o.

• Celsius: water freezes at 0o and boils at 100o.

• Note: A degree Celsius is almost twice as large as a degree Fahrenheit.

Converting between C and F

• Celsius: (oF- 32) x .55

• Fahrenheit: (oC x 1.8) + 32o

Practice Problem 1

• Question: 32oC is equivalent to what Fahrenheit temperature?

• Answer: 89.6oF

Practice Problem 2

• Question: 95oF is equivalent to what Celsius temperature?

• Answer: 34.7oC

Kelvin

• The SI base unit of temperature is the kelvin (K).

• A temperature of 0 K [absolute zero] refers to the lowest possible temperature that can be reached (over 500 below 0 in oF).

• In oC, this temperature is -273.15.

Converting between C and K

• K = oC + 273

• See Figure 19 on p. 20.