Chemistry - Chapter 1 Flashcards

1.1 What Is Chemistry, and What Can Chemistry Do for You?

• Chemistry helps answer questions about everyday phenomena.
  • Why boiling water bubbles and produces steam.
  • How tea leaves change the water's color.
  • Why sugar makes tea sweet and tea itself is bitter.
  • The effect of methyl bromide on the ozone layer.
  • How gasoline burns and pollutes, and the function of catalytic converters.
  • Why some old books crumble while others remain intact and if damaged books can be saved.
• Chemists study the structure of matter and its changes.
  • Matter can be solid, liquid, or gaseous.
• Chemistry is defined as the study of the structure and behavior of matter.
• Chemists develop new materials and drugs.
  • Lighter and stronger airplanes.
  • Environmentally friendly disposable cups.
  • Efficient anti-pollution devices.
  • Drugs to fight cancer, control allergies, and promote hair growth.
• Chemists' creations have had mixed reviews, such as the use of CFCs and durable plastics.
• Most chemists have a strong social conscience, working to create safer chemicals and clean up the environment.
• Introductory chemistry focuses on teaching basic principles and skills needed for understanding the physical world.

1.2 Suggestions for Studying Chemistry

• Chemistry includes many topics that need to be learned cumulatively.
• Being organized and diligent is crucial for studying chemistry.
• There is no single correct way to study chemistry; the technique depends on the student's level, time available, strengths, and attitude.
• Use the Review Skills sections in the textbook to identify and review necessary skills from earlier chapters.
• Read each chapter before it is covered in lecture to provide a knowledge skeleton.
• Attend class meetings, take notes, and participate in class discussions to be actively involved.
• Reread the chapter, marking important sections and working practice exercises.
• Examples in each chapter show how to do tasks that will be asked on exams. The examples are followed by Exercises.
• Apply the 15-minute rule: If you spend more than 15 minutes on an idea or problem and still do not understand it, ask for help.
• Use chapter objectives as a focus of study.
• Write out responses to objectives that begin with "Explain…" or "Describe…".
• Write out stepwise procedures that work best for you.
• Use the computer-based tools that accompany the course.
• Work some problems at the end of the chapter after completing all the previous steps.
• Ask for help when needed, whether from the instructor or a study group.
• Review for the exam by reading the list of objectives and working end-of-chapter problems.

1.3 The Scientific Method

• There is no one correct way to do science; different disciplines and scientists have different approaches.
• Most scientific work shares common characteristics, which can be seen in the story of how scientists discovered the first treatment for Parkinson's disease.
  • Observation and collection of data: Scientists observed that South American manganese miners were developing symptoms similar to those of Parkinson's disease.
  • Initial hypothesis: The symptoms of the manganese miners and Parkinson's sufferers had a common cause.
  • Systematic research or experimentation: Study of the manganese miners' brain chemistry showed that manganese interferes with the work of dopamine.
  • Refined hypothesis: Brains of Parkinson's sufferers had low levels of dopamine. Brain studies confirmed this.
  • Publication of results: Other scientists repeated the research and confirmed the conclusions.
  • Search for useful applications: A drug that would elevate the levels of dopamine in the brain was sought.
  • Levodopa, or L-dopa, was found to meet these requirements.
• The development of applications often leads to another round of hypothesizing and testing to refine the applications.
  • L-dopa caused remission of Parkinson's disease in about one-third of patients and improvements in another one-third, but there were problematic side effects.
  • L-dopa is now given with levocarbidopa to inhibit its conversion to dopamine outside the brain.
• The cycle of hypothesis, experimentation, and finding new applications continues.

1.4 Measurement and Units

• The practice of chemistry demands both accuracy and clarity.
• A measurement is always reported as a value, a quantitative description that includes both a number and a unit.
• Units are quantities defined by standards that people have agreed to use to compare one event or object to another.
• The French invented the metric system in the 18th century, based on a more consistent, systematic, and carefully defined set of standards.
• The International System of Measurement (SI) was set up in 1960 to provide a very organized, precise, and practical system of measurement.
• The SI system is constructed using seven base units, from which all other units are derived.
  • Meter (m) for length.
  • Kilogram (kg) for mass.
  • Second (s) for time.
  • Kelvin (K) for temperature.
  • Mole (mol) for amount of substance.

SI Units Derived from Base Units

• Many properties cannot be described directly with one of the seven SI base units.
  • Volume is derived from the base unit for length, the meter.
  • Volume can be defined as length cubed, so cubic meters, m^3, can be used as a volume unit.
  • Chemists prefer to use the liter as the base unit for volume. A liter (L) is 1/1000 (or 10^{-3}) of a cubic meter, so there are 1000 (or 10^3) liters per cubic meter.
    • 1 L = 10^{-3} m^3 or 10^3 L = 1 m^3

SI Units Derived from Metric Prefixes

• SI base units and derived units are not always a convenient size for making measurements, so prefixes are attached to the base units to multiply or divide the base unit by a power of 10.
• Common metric prefixes include:
  • giga (G): 1,000,000,000 or 10^9
  • mega (M): 1,000,000 or 10^6
  • kilo (k): 1000 or 10^3
  • centi (c): 0.01 or 10^{-2}
  • milli (m): 0.001 or 10^{-3}
  • micro ($\mu$): 0.000001 or 10^{-6}
  • nano (n): 0.000000001 or 10^{-9}
  • pico (p): 0.000000000001 or 10^{-12}
• A kilometer is 10^3 meters. The abbreviation for kilometer is km: 1 kilometer = 10^3 meter or 1 km = 10^3 m.
• A micrometer is 10^{-6} meters. The abbreviation for micrometer is $\mu$m. The symbol $\mu$ is the Greek letter mu: 1 micrometer = 10^{-6} meter or 1 \mu m = 10^{-6} m.

More about Length Units

• Although scientists rarely use the centuries-old English system of measurement, it is still commonly used in the United States to describe quantities in everyday life.
• A kilometer is a little more than 1/2 mile.
• The distance between the floor and a typical doorknob is about 1 meter.
• The width of the fingernail on your little finger is probably about 1 centimeter.
• The diameter of the wire used to make a typical paper clip is about 1 millimeter.

More About Volume Units

• A liter is slightly larger than a quart.
• There are 4.93 milliliters in a teaspoon, so when the label on the bottle of a typical liquid children's pain reliever suggests a dosage of one teaspoon, the volume given will be about 5 milliliters.
• There are 29.57 milliliters per fluid ounce (fl oz). A typical bottle of nail polish contains 0.5 fl oz.
• Another common volume unit is the cubic centimeter, cm^3, which is equivalent to a milliliter. 1 cm^3 = 1 mL

Mass and Weight

• Mass and weight are related but not identical.
• Mass is a measure of the amount of matter in an object.
• Weight is a measure of the force of gravitational attraction between an object and a significantly large body, such as the earth or the moon.
• Mass can be defined as the property of matter that leads to gravitational attractions between objects and therefore gives rise to weight.
• In the SI system, units such as gram, kilogram, and milligram are used to describe mass.
• The accepted SI force unit is the newton, N. If your mass is 65 kg, your weight on the surface of the earth is 637 N.

Temperature

• Temperature is a measure of the average motion of the particles in a system.
• For the Celsius scale, the temperature at which water freezes is defined as 0 °C, and the temperature at which water boils is defined as 100 °C.
• For the Fahrenheit scale, the temperature at which water freezes is defined as 32 °F, and the temperature at which water boils is defined as 212 °F.
• There are 180 °F between freezing and boiling water (212 - 32 = 180), so a degree Fahrenheit, °F, is 1/180 of the temperature difference between freezing and boiling water.
• There are 180 °F per 100 °C, or 1.8 °F per 1 °C.
• The unit of measurement in the Kelvin scale is called the kelvin, K. The value 0 K is defined as absolute zero, the lowest possible temperature.
• Absolute zero is 0 K, -273.15 °C, and -459.67 °F.
• The kelvin is defined so that its size is equal to the size of a degree Celsius.
• The highest temperatures in the universe are thought to be inside some stars, where theory predicts temperatures of about 10^9 K (a billion kelvins).

1.5 Reporting Values from Measurements

• All measurements are uncertain to some degree.

Accuracy and Precision

• Precision describes how closely a series of measurements of the same object resembles each other.
• Accuracy describes how closely a measured value approaches the true value of the property.

Describing Measurements

• Scientists report all of the certain digits and one estimated (and thus uncertain) digit.
• The surface of a liquid in a graduated cylinder is usually slightly curved. The surface is called a meniscus. Scientists follow the convention of using the bottom of the meniscus for their reading.
• Scientists assume that the number in the last reported decimal place has an uncertainty of $\pm$1 unless stated otherwise.
• Sometimes, it is necessary to use trailing zeros to show the uncertainty of a measurement.
• The conventional practice is to report all of your certain digits and one estimated digit unless you are told to do otherwise.

Digital Readouts

• Electronic balances have a digital readout that reports the mass of objects to many decimal positions.
• You should report all of the digits on the display unless told to do otherwise.