Chapter 1: Introduction to Chemistry. What is chemistry? O The study of the composition of matter...
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Transcript of Chapter 1: Introduction to Chemistry. What is chemistry? O The study of the composition of matter...
Chapter 1: Introduction to Chemistry
What is chemistry?OThe study of the composition of matter and the changes it undergoes.
OWhat is matter?OAnything that has mass and occupies space.
What’s the Difference Between Mass and Weight?
Mass WeightO Measure of the
amount of matter in an object.
O Needs a balance.
O A force that measures the pull of gravity on an object.
O Needs a scale.
Five Areas of Chemistry
O Organic Chemistry: chemicals containing carbon
O Inorganic Chemistry: chemicals NOT containing carbon
O Biochemistry: processes in organismsO Analytical Chemistry: composition of
matterO Physical Chemistry: mechanism, rate, and
energy transfers in matter during changes
Which area of study matches each of the following?
ODeveloping processes for efficient steel production
OStudying how lack of calcium affects bone growth
OMeasuring amount of lead in drinking water
OResearching differences between C2H5OH and CH3OH
OComparing energy differences needed to walk up or run up steps
Two Types of Chemical Research
Pure ChemistryApplied
ChemistryO Pursuit of
chemical knowledge for its own sake
O “I’ll experiment and see what I discover.”
O Research for a practical goal or application.
O “I’m looking for a cure for cancer.”
Why Study Chemistry?O Explains the natural worldO Energy, medicine, materials,
biotechnology, agriculture, environment, universe
O Helps prepare for a careerO Many different jobs using
chemistryO Helps create informed citizens
Antoine Lavoisier
O “Father of Modern Chemistry”O Changed chemistry from
observations to measurementsO Determined that oxygen is needed to
burnO Found and named elementsO Wrote textbooksO Law of Conservation of MatterO Made very precise balance, great labO Collaborated scientifically with peers
Scientific Method
OLogical, systematic approach to a scientific problem
OObservation: using senses to get information
OHypothesis: proposed explanation for an observation
OExperiment: procedure to test a hypothesis
Variables in an ExperimentManipulated
(Independent) Variable
Responding (Dependent) Variable
O What the experimenter changes
O Often time or temperature
O Plotted on x-axis
O The variable observed in an experiment
O Plotted on y-axis
What’s the Difference Between a Theory and a Law?
Scientific Theory Scientific Law
O Well-tested explanation for a broad set of observations
O Cannot be provedO Theory of Relativity,
Big Bang Theory
O Concise statement summarizing results of many experiments and observations
O Laws of Gravity, Law of Conservation of Matter
Experiments
TheoryHypothesis
Scientific Law
Observations
May be revised May be modified
Summarizes the results of many observations and experiments
Graphing in Chemistry
OGraphs display data in a concise form.
OGraphs predict trends in data.OGraphs allow extrapolation to points
beyond data limits.OLine graphs very common.OFive major parts: title, independent
variable, dependent variable, scales for each axis, legend (if needed)
Graph TitleO ALWAYS y-axis name vs. x-axis
name!O DO NOT use abbreviations in title
except for vs.
Velocity vs. Time
Independent (Manipulated) Variable
OControlled by experimenterOIncludes time, depth,
temperatureOPlaced on x-axis (horizontal
axis)
Dependent (Responding) Variable
ODirectly affected by the independent variable
OChanges in response to changes in independent variable
OPlaced on y-axis
Scales for Each Axis
O Must include all data points.O Scale for each axis is dictated by
data values.O Axis scales are independent of each
other (both do not have to start on same number).
O Scales DO NOT have to start at zero!O Scale MUST be consistent on the axis
(same interval throughout).O DO NOT USE A BREAK ON THE SCALE!
Example of Scales
Breaks on Axis
DO NOT USE A BREAK ON YOUR GRAPH!
Axes Titles and UnitsO Each axis needs a title and a unit.O Do not abbreviate titles.O Put the unit in parenthesis after the
title.Voltage vs. FrequencyVoltage vs.
Frequency
Legend
OOnly used when needed for clarity.
OShort and concise.
Line of Best Fit GraphsOFrequently used in chemistry.OIf data points do not form a
straight line, line is drawn as an average through the points.
ODraw one thin line using a ruler.
Extrapolation O To infer or estimate by extending or
projecting from known information.O Can get information on points not
tested in lab.O Make dotted line with a ruler to
extend graph.