Chapter 1: Introduction to Chemistry

What is chemistry? O The study of the composition of matter and the changes it undergoes. O What is matter? O Anything that has mass and occupies space.

What’s the Difference Between Mass and Weight? Mass Weight O 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 organisms O Analytical Chemistry: composition of matter O Physical Chemistry: mechanism, rate, and energy transfers in matter during changes

Which area of study matches each of the following? O Developing processes for efficient steel production O Studying how lack of calcium affects bone growth O Measuring amount of lead in drinking water O Researching differences between C 2 H 5 OH and CH 3 OH O Comparing energy differences needed to walk up or run up steps

Two Types of Chemical Research Pure Chemistry Applied Chemistry O 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 world O Energy, medicine, materials, biotechnology, agriculture, environment, universe O Helps prepare for a career O Many different jobs using chemistry O Helps create informed citizens

Antoine Lavoisier O “Father of Modern Chemistry” O Changed chemistry from observations to measurements O Determined that oxygen is needed to burn O Found and named elements O Wrote textbooks O Law of Conservation of Matter O Made very precise balance, great lab O Collaborated scientifically with peers

Scientific Method O Logical, systematic approach to a scientific problem O Observation: using senses to get information O Hypothesis: proposed explanation for an observation O Experiment: procedure to test a hypothesis

Variables in an Experiment Manipulated (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 proved O 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 Theory Hypothesis Scientific Law Observations May be revised May be modified Summarizes the results of many observations and experiments

Graphing in Chemistry O Graphs display data in a concise form. O Graphs predict trends in data. O Graphs allow extrapolation to points beyond data limits. O Line graphs very common. O Five major parts: title, independent variable, dependent variable, scales for each axis, legend (if needed)

Graph Title O ALWAYS y-axis name vs. x-axis name! O DO NOT use abbreviations in title except for vs. Velocity vs. Time

Independent (Manipulated) Variable O Controlled by experimenter O Includes time, depth, temperature O Placed on x-axis (horizontal axis)

Dependent (Responding) Variable O Directly affected by the independent variable O Changes in response to changes in independent variable O Placed 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 Units O Each axis needs a title and a unit. O Do not abbreviate titles. O Put the unit in parenthesis after the title. Voltage vs. Frequency

Legend O Only used when needed for clarity. O Short and concise.

Line of Best Fit Graphs O Frequently used in chemistry. O If data points do not form a straight line, line is drawn as an average through the points. O Draw 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.