Chemistry Review Flashcards

Chemistry: The Science of Matter

Chemistry is the science that deals with the structure and behavior of matter.

The Scientific Method

The scientific method is a systematic approach to gaining knowledge. Although there isn't one single way to conduct science, it generally involves these steps:

• Observation and Data Collection: Gathering information. Example: Scientists observed that South American manganese miners exhibited Parkinson's-like symptoms.

• Initial Hypothesis: Forming a testable explanation based on observations. Example: The symptoms in manganese miners and Parkinson's sufferers may share a common cause.

• Systematic Research and Experimentation: Conducting experiments to test the hypothesis. Example: Research revealed that manganese interferes with dopamine, a crucial brain chemical for muscle control. High manganese levels could lead to movement problems.

• Hypothesis Refinement: Refining the hypothesis based on experimental results. Example: Researchers hypothesized that Parkinson's sufferers have low dopamine levels. Brain studies confirmed this.

• Publication of Results: Sharing findings with the scientific community.

• Confirmation or Refutation: Other scientists repeat the research to validate or disprove the conclusions. Example: Other scientists confirmed the dopamine research results.

• Search for Useful Applications: Exploring practical applications of the findings. Example: Researchers sought compounds that could penetrate the brain and convert into dopamine, leading to the discovery of Levodopa (L-dopa).

• Development and Refinement of Applications: Further testing and modification to improve applications. Example: Addressing side effects of L-dopa like nausea and blood pressure issues by co-administering it with levocarbidopa.

The scientific method is an iterative process, with the cycle continuing as new observations are made and applications are refined.

Measurement and Units

• A value from a measurement incudes a unit and a number describing a quantity.

• Units are quantities defined by agreements so people can compare events or objects.

Base Units (International System of Measurement)

• Length: meter (m) - the distance that light travels in a vacuum in 1/299,792,458 of a second.

• Mass: kilogram (kg) - the mass of a platinum-iridium alloy cylinder stored in France.

• Time: second (s) - the duration of 9,192,631,770 periods of radiation emitted by cesium-133 during a specific energy level transition.

• Temperature: kelvin (K) - 1/273.16 of the temperature difference between absolute zero and the triple point of water.

Derived Units

• Cubic meter: 1 cubic meter = 1000 liters

• 1 L = 10^{-3} m^3

• 10^3 L = 1 m^3

Common Units and Abbreviations

• Length: meter (m)

• Mass: gram (g)

• Volume: liter (L or l)

• Energy: joule (J)

Scientific (Exponential) Notation

Numbers in scientific notation follow the format: a
umber 10^b, where:

• a is the coefficient (a number with one nonzero digit to the left of the decimal point).

• b is the exponent (a positive or negative integer).

• 10^b is the exponential term

Example: 5.5
umber 10^{21} carbon atoms in a 0.55 carat diamond.

• Coefficient: 5.5

• Exponential term: 10^{21}

• Exponent: 21

Uncertainty:

The coefficient reflects the uncertainty. It's generally assumed to be plus or minus one in the last reported position, unless stated otherwise. E.g., 5.5
umber 10^{21} suggests a range from 5.4
umber 10^{21} to 5.6
umber 10^{21}.

Magnitude:

The exponential term indicates the number's size.

• Positive exponents: large numbers (e.g., 2.2
  umber 10^4 = 22,000).

• Negative exponents: small numbers (e.g., 5.6
  umber 10^{-4} = 0.00056).

Converting Decimal to Scientific Notation:

1. Move the decimal until there's one nonzero digit to its left, counting the shifts.

2. Write the result as the coefficient times 10^b, where b is positive if you moved the decimal left, and negative if you moved it to the right. (e.g., 22,000 becomes 2.2
   umber 10^4; 0.00056 becomes 5.6
   umber 10^{-4}).

Metric Prefixes

Converting Scientific Notation to Decimal:

• Move the decimal in the coefficient right if the exponent is positive, and left if negative.

• The exponent's number indicates how many positions to shift the decimal (e.g., 2.2
  umber 10^4 becomes 22,000; 5.6
  umber 10^{-4} becomes 0.00056).

Advantages of Scientific Notation:

• Convenience: Shorter representation of very large or small numbers (e.g., electron mass as 9.1096
  umber 10^{-28} g).

• Clarity in uncertainty: Better conveys the uncertainty in a value.

Exponential Term Operations:

• Multiplication: Add exponents (e.g., 10^3
  umber 10^6 = 10^9).

• Division: Subtract exponents.

• Raising to a Power: Multiply exponents (e.g., (10^4)^3 = 10^{12}).

Length Conversions

• 1 km = 0.6214 mi

• 1 mi = 1.609 km

• 1 m = 3.281 ft

• 1 ft = 0.3048 m

• 1 in. = 2.54 cm = 25.4 mm

• 1 cm = 0.3937 in.

• 1 mm = 0.03937 in.

Volume Conversions

• 1 mL = 0.03381 fl oz

• 1 fl oz = 29.57 mL

• 1 gal = 3.785 L

• 1 L = 1.057 qt = 0.2642 gal

• 1 qt = 0.9464 L

Mass and Weight

Mass: Measure of the amount of matter in an object. Property of matter that leads to gravitational attractions between objects and therefore gives rise to weight.

• Matter is anything that occupies volume and has mass.

Weight: Measure of the force of gravitational attraction between an object and the Earth.

Mass Conversions

• 1 oz = 28.35 g

• 1 lb = 453.6 g

• 1 kg = 2.205 lb

• 1 Mg = 1000 kg = 1 t

Temperature Scales

• Celsius: Freezing point of water is 0^
  umber C, boiling point is 100^
  umber C.

• Fahrenheit: Freezing point of water is 32^
  umber F, boiling point is 212^
  umber F.

• Kelvin: Absolute scale where 0 K is absolute zero. Freezing point of water is 273.15 K, boiling point is 373.15 K.

Reporting Values from Measurements

Values should include

• Precision: describes how closely a series of measurements of the same object resemble each other; related to reproducibility.

• Accuracy: A measurement’s relationship to the property’s true value.

Measurements should contain all certain digits plus one estimated (uncertain) digit.