Scientific Method

Scientific Method
Introduction to Chemistry Lesson 2

Scientific Method The scientific method is a systematic approach used in scientific studies of the world around us. There are five basic steps Observation Literature Review Hypothesis Experimentation and Data Collection Conclusion

Observation An observation is the act of gathering information. Types of information can include Qualitative data Color, odor, shape, or other physical characteristic Anything that can be observed with the five senses Quantitative data Measurements of speed, mass, height, temperature, pressure, volume, and density These are numerical data

Literature Review Lets you discover what other scientists might know about your observation. This includes the experiments that have performed, the data collected, and their conclusions. This keeps you from repeating someone else’s work. It also may answer questions that you have.

Hypothesis A hypothesis is a tentative explanation for what has been observed. It is your best guess as to why your observation is occurring. Hypotheses are normally stated as an If…then statement. For example: If magnesium ribbon is burned in the presence of oxygen, then it will produce magnesium oxide, heat and a brilliant white light. All hypotheses should be tested using experimentation or further observation.

Experimentation An experiment is a set of controlled observations that test the hypothesis. Scientists must plan and set up one or more experiments in order to change one variable at a time. All the other variables must remain constant. Scientists also set up a control experiment where none of the variables are changed so that they can compare the results of the other experiments to the control to see how the results differ each time.

A variable is a quantity or condition that can have more than one value. The variable that is changed is the independent variable. The variable that remains constant is the dependent variable. The experiment should be set up in order to DISPROVE the hypothesis. Scientists write out every step they follow in the experiment so that other scientists are able to repeat the experiment if necessary and obtain similar, if not exactly, the same results.

Data Collection During the experiment scientist record any changes that they observe. These observations are called data. If the temperature increases, they write down the change in temperature at certain intervals of time. If a new substance is formed, they measure the mass of the substance and record it along with other quantitative and/or qualitative observations. The data and observations are then analyzed to see if they disprove or support the hypothesis.

Conclusion A conclusion is reached when scientists review the data that has been analyzed and apply the analysis to the hypothesis. The conclusion is a judgment based on the information obtained during the experiment. A hypothesis can never be proved, only failed to be disproven. If an experiment disproves a hypothesis, the hypothesis must be discarded or modified and then retested through further experimentation.

Models Models can be constructed based on analyzed data to give scientists a visual representation of what occurred during the experiment. Models can also be constructed based on the conclusion that is reached. Models can be tested and used to make predictions. If the model works and can be used to make accurate predictions, the is helps to support a hypothesis and fails to disprove the hypothesis. If a model cannot be used to make accurate predictions, it must be discarded and a new model constructed.

Publishing and Peer Review Science only moves forward when new knowledge is discovered and shared. If a scientist doesn’t publish his experiment and conclusion, then no one will know what was discovered. Peer review is the process where other scientists review your published work and try to obtain the same results that you obtained and reach the same conclusions that you reached. If they have any problems repeating your experiment or don’t come to a similar conclusion, they will probably publish their results and questions will be raised about your experimental practices.

Theory A scientific theory is an explanation that has been supported (failed to be disproven) by many, many, experiments. It states a broad principle of nature that has been supported over time. All theories are still subject to new experimentation and can be modified.

Scientific Law Scientific laws arise when many scientists come to the same conclusion about certain relationships in nature. These relationships are often represented mathematically to show the relationships between two or more variables. A scientific law arises after hundreds of years of experimentation that fails to cause modifications to a scientific theory.

Scientific Method