Chapter 1: Introduction to Chemistry Section 1.3: Scientific Methods

The Scientific Method Systematic study Method of verification Common among all scientists

Steps of the Scientific Method

Observations Qualitative Data Quantitative Data The five senses Numerical information

Qualitative or Quantitative? The substance is yellow The unknown has a boiling point of 123 degrees Celsius Sulfur has a pungent odor Sodium Nitrate has a density of 2.26 g/cm3

Hypothesis Remember the Tale of Two Chemicals? Testable statement or predication Based on observations Tentative explanation of events

Experiments Set of controlled observations that test the hypothesis Must be carefully planned and conducted Test one variable at a time

Variable Quantity or condition that can have more than one value Examples?

Two Variables Independent Variable Dependent Variable The one you plan to change Should be the only thing affecting the dependent variable Dependent Variable The one you did not change Changes in response to independent variable

Control Valuable to experiment Standard for comparison Helps you better understand the behavior of independent and dependent variables

Conclusion 1st: Analyze the data gathered during the experiment. 2nd: Apply analysis to your hypothesis 3rd: Make a judgment based on the information

Hypothesis: Never proven, only supported by an experiment Theory: Must be supported by many, many experiments Scientific Law: a relationship in nature that has been proven by many scientists many times without exceptions