Chapter 1 Notes: Chemistry in Our Lives (Collected Section-by-Section Overview)

Section 1: Chemistry and Chemicals

  • Chemistry is the study of matter (anything that has volume and takes up space).

    • Focuses on composition, structure, properties, and reactions.

    • Occurs all around us all the time (e.g., cooking, cleaning with bleach, hair processing, starting your car).

  • Substances have the same composition and properties wherever they are found.

    • All things you can see around you are made up of chemicals.

    • Examples of chemicals in everyday products:

    • Toothpaste

    • Soaps/Shampoos

    • Cosmetics/Lotions

    • Food

    • Water

  • Common chemicals in toothpaste and their functions:

    • Calcium carbonate: used as an abrasive to remove plaque

    • Sorbitol: prevents loss of water and hardening of toothpaste

    • Sodium lauryl sulfate: loosens plaque

    • Titanium dioxide: makes toothpaste white and opaque

    • Sodium fluorophosphate: prevents formation of cavities by strengthening tooth enamel

    • Methyl salicylate: gives toothpaste a pleasant wintergreen flavor

  • Practice question (conceptual):

    • "Fruit, Milk, Sunlight, Breakfast cereal — Which of the following does NOT contain a chemical?"

    • Note: In chemistry, everything is made of chemicals; this is a trick question used to emphasize that all matter is chemical.

  • Quick reminder: Chemicals around us are studied in context of everyday examples and consumer products.

Section 2: Scientific Method

  • Scientific Method overview: a general framework for how scientists think and work.

    • Process is described as a series of steps; individuals may vary in how they apply them.

    • Everyone can act like a scientist.

  • Core steps (Section 2):
    1) Observations: (Is the question) Make an observation and ask questions; do background research.
    2) Hypothesis: A tentative explanation or proposed answer to the question. (the statement)
    3) Experiments: Design and perform experiments to test the relationship between hypothesis and observation; if results fail, redesign; if results do not support the hypothesis, modify the hypothesis and plan new experiments.
    4) Conclusion: If experiments produce consistent results, the hypothesis is considered true.

  • Law vs. Theory (scientific terminology):

    • Law: An observation that consistently holds true; does not explain why the observation occurs.

    • Example: Law of Gravity predicts that a book will fall if dropped, but does not explain why it falls.

    • Theory: A well-supported explanation of observations, based on many independent experiments.

  • Example applying the Scientific Method:

    • Cat allergy scenario:

    • Observation: You sneeze when visiting a friend who has a new cat and you haven't sneezed at their home before.

    • Hypothesis: You are allergic to cats.

    • Test: Visit other homes with cats to see if sneezing occurs.

    • Conclusion: If sneezing occurs at all homes with a cat, the hypothesis is supported (you are allergic to cats).

  • Practical example exercise from the slides:

    • Observation: Trainer records that you ran for 25 minutes on the treadmill.

    • Conclusion (from broader context): Scientific studies show that exercising lowers blood pressure.

    • Hypothesis: Your weight loss is due to increased exercise.

    • Identification task: Classify the given statements as observation, hypothesis, experiment, or conclusion.

Section 3: Studying and Learning Chemistry

  • Success in chemistry requires:

    • Good study habits

    • Connecting new information to prior knowledge

    • Rechecking what has been learned and what may have been forgotten

    • Retrieving information for exams

    • Studying in ways that promote long-term memory storage

  • Key idea: You need to study in a way that stores information in long-term memory.

  • Rehearsal Loop (memory model):

    • Sensory input → Sensory Memory → Short-Term Memory → Encoding → Long-Term Memory

    • Important notes:

    • Unattended information is lost

    • Unrehearsed information is lost

    • Retrieval can cause information to be lost over time

  • Four Methods of Retrieval Practice (examples):

    • Exit Tickets

    • Starter quizzes / Multiple choice quizzes / Short answer tests / Free write

    • Think, pair, share / Ranking & Sorting

    • Brain dump: Write or draw everything you know about a topic

    • Flashcards: Time-limited practice; include links between cards

    • Quizzing: Create practice questions and swap with a partner

    • Knowledge organizers: Templates for key information; include definitions, topic, examples, non-examples

  • Additional retrieval strategies:

    • After retrieving as much as you can, go back to the books and fill in missing information

    • Use knowledge organizers to learn new vocabulary and relate ideas across subjects

  • Strategies to improve learning and understanding:

    • Don’t simply reread textbooks or notes; it can create familiarity without true learning

    • Ask yourself questions while reading

    • Actively interact with material to store in long-term memory

    • Self-test with quizzes and practice problems

    • Use example problems from the text without notes

    • Study in regular intervals rather than cramming

    • Create a study plan and stick to it

    • Study different topics and relate new concepts to prior knowledge

Section 4: Key Math Skills for Chemistry

  • Section focus: Key math skills needed in chemistry (Section 4)

  • Coming into class you should be able to:

    • Identify place values

    • Use positive and negative numbers in calculations

    • Calculate percentages

    • Solve equations

    • Interpret graphs

    • Calculating an average is an extra topic listed by Dr. Tucker

  • Place value:

    • Definition: The position of a specific digit in a number.

  • Positive/Negative numbers in multiplication/division:

    • Rule: If both numbers have the same sign (both positive or both negative), the product or quotient is positive.

    • If the signs are different, the result is negative.

    • Examples (interpreting the slide content):

    • 2imes3=62 imes 3 = 6

    • (−2)imes(−3)=6(-2) imes (-3) = 6

    • 2imes(−3)=−62 imes (-3) = -6

    • (−2)imes4=−8(-2) imes 4 = -8

    • 6 ig/ (-2) = -3

    • (-8) ig/ 2 = -4

  • Addition of positive and negative numbers:

    • When adding two positives, the sum is positive.

    • When adding two negatives, the sum is negative.

    • When adding a positive and a negative, subtract the smaller magnitude from the larger magnitude; sign is that of the larger magnitude.

    • Examples:

    • 2+(−3)=−12 + (-3) = -1

    • 3−2=13 - 2 = 1

    • 2+(−3)=−12 + (-3) = -1

    • (−3)+8=5(-3) + 8 = 5

    • The larger magnitude determines the sign (negative for the first, positive for the second in these examples).

    • Additional example from slide: 2+3=52 + 3 = 5 and (−2)+(−3)=−5(-2) + (-3) = -5

  • Subtraction of positive and negative numbers:

    • Subtraction rules:

    • 7−(−3)=107 - (-3) = 10

    • 6−4=26 - 4 = 2

    • 4−6=−24 - 6 = -2

    • 18−12=618 - 12 = 6

    • 12−18=−612 - 18 = -6

    • −12−(−5)=−7-12 - (-5) = -7

    • Note: Subtracting a negative is equivalent to adding the positive: a−(−b)=a+ba - (-b) = a + b

  • Percentages:

    • Definition: Percentage signifies a fraction out of 100; Fraction = part/whole; Whole = 100 for a percentage.

    • Formula: ext{percent} = rac{ ext{part}}{ ext{whole}} imes 100 ext{%}

    • Example 1: A bullet weighs 15.1 g and contains 13.9 g of lead.

    • ext{Lead ext{percent}} = rac{13.9}{15.1} imes 100 ext{%} \approx 92 ext{%}

    • Example 2: A bullet contains 11.6 g lead, 0.5 g tin, and 0.4 g antimony. What is the % of tin?

    • ext{Tin ext{percent}} = rac{0.5}{11.6+0.5+0.4} imes 100 ext{%} \approx 4 ext{%}

  • Solving equations (two methods shown on slides):

    • Balancing method:

    • Example: 8a−5=118a - 5 = 11

    • Add 5 to both sides: 8a=168a = 16

    • Divide both sides by 8: a=2a = 2

    • Function machine method:

    • Example: 8a−5=118a - 5 = 11

    • Interpret as: apply x8, subtract 5, then go to 11, solve for a.

    • Another example from slides:

    • 10+6y=3410 + 6y = 34

    • Subtract 10: 6y=246y = 24

    • Divide by 6: y=4y = 4

  • Graphs and interpretation:

    • Represents the relationship between two variables.

    • Example described: Title: Volume of a Balloon versus Temperature.

    • Axes: Horizontal axis (x-axis) = Temperature (°C); Vertical axis (y-axis) = Volume (L).

    • Dots represent data points; a straight line indicates a direct relationship; as one variable increases, the other increases; or as one decreases, the other decreases.

    • Use the line to estimate volume at various temperatures; given example: When temp = 50 °C, volume = 26.5 L.

  • Averages (mean):

    • Process: Add all data points and divide by the total number of data points.

    • Example: Average of 23, 39, 24, 33, 28, 42.

Section 5: Writing Numbers in Scientific Notation

  • Purpose: A convenient way to express very large or very small numbers.

  • Structure: Has two parts – a coefficient and a power of 10.

    • Scientific notation format: x=aimes10nx = a imes 10^{n} where a is the coefficient and n is the exponent.

  • Examples of numbers in scientific notation (from table):

    • Volume of gasoline used in the United States each year: 5.5imes1011extL5.5 imes 10^{11} ext{ L}

    • Diameter of Earth: 1.28imes107extm1.28 imes 10^{7} ext{ m}

    • Average volume of blood pumped in 1 day: 8.5imes103extL8.5 imes 10^{3} ext{ L}

    • Time for light to travel from the Sun to Earth: 5.00imes102exts5.00 imes 10^{2} ext{ s}

    • Mass of a typical human: 6.8imes101extkg6.8 imes 10^{1} ext{ kg}

    • Mass of the stirrup bone in the ear: 3.0imes10−3extg3.0 imes 10^{-3} ext{ g}

    • Diameter of the Varicella zoster virus (chickenpox): 3.0imes10−7extm3.0 imes 10^{-7} ext{ m}

    • Mass of a bacterium (Mycoplasma): 1imes10−18extkg1 imes 10^{-18} ext{ kg}

  • Converting between scientific notation and regular notation:

    • Examples to convert to scientific notation:

    • A. 64,000 → 6.4imes1046.4 imes 10^{4}

    • B. 0.021 → 2.1imes10−22.1 imes 10^{-2}

    • Converting from scientific notation to regular notation:

    • 8.28imes10−4<br>ightarrow0.0008288.28 imes 10^{-4} <br>ightarrow 0.000828

    • 4.02imes103<br>ightarrow40204.02 imes 10^{3} <br>ightarrow 4020

  • Quick practice problems (as shown):

    • A. 64,00064{,}000; B. 0.0210.021, write each in scientific notation.

    • A. 8.28imes10−48.28 imes 10^{-4}; B. 4.02imes1034.02 imes 10^{3}, convert to regular notation.

  • Note: The slides show additional example computations and conversions; the essential idea is understanding the coefficient and exponent and how to move decimal places accordingly.

Quick reference: Key formulas and concepts

  • Scientific notation: x = a imes 10^{n}, ext{ with } 1
    less |a| < 10, ext{ and } n ext{ integer}

  • Percent formula: extpercent=racextpartextwholeimes100%ext{percent} = rac{ ext{part}}{ ext{whole}} imes 100\%

  • Addition/subtraction with signs examples: 2+(−3)=−1, 7−(−3)=10, (−12)−(−5)=−72 + (-3) = -1,\ 7 - (-3) = 10,\ (-12) - (-5) = -7

  • Multiplication/Division with signs: same signs -> positive; opposite signs -> negative

  • Place value: position of a digit in a number determines its value

  • Graph interpretation: data points, direct relationship, use line to interpolate; key example: temperature vs balloon volume

  • Conceptual workflow (scientific method): Observation → Hypothesis → Experiment → Conclusion

  • Theory vs. Law: Law describes what happens; Theory explains why

  • Retrieval practice strategies: exit tickets, quizzes, brain dump, flashcards, knowledge organizers, etc.

64,000—— 6.4 × 10 ^4

0.021——- 2.1 × 10 ^-2

0.000828

4020