The Scientific Method

Scientific Method Scientific Law Scientific Method and Law Theories and Laws Why Dinosaurs Disappeared The Hellenic Market Four-Element Theory Drunken Goldfish Science and Morality

Using the scientific method requires that one be a good observer. observationinference involves a judgment or assumption uses the five senses

The Skeptical Chemist Robert Boyle Published “The Sceptical Chymist” scientific speculation …stated that scientific speculation was worthless unless it was supported experimental evidence by experimental evidence. scientific method This principle led to the development of the scientific method. (in 1661)

“My mother the eye doctor” Observation or Inference? One player is holding a bat.The player holding the bat is talking.One of the teams is called the “Reds.” One player is wearing a catcher’s mask. One player is a catcher.Names are written on the uniforms.The players in the picture are on opposite teams.The adult is the umpire.The piece of paper is a note from the mother of the batter.The adult is holding a piece of paper.The mother of the batter is an optometrist or opthalmologist (an eye doctor).

Data Observations are also called data. There are two types of data. qualitative dataquantitative data descriptions; measurements; no numbersmust have numbers

Parts of the Scientific Method Identify an unknown. Make a hypothesis (a testable prediction). Experiment to test the hypothesis. Draw a valid conclusion.

A Scientific Experiment procedure the order of events in an experiment; the “recipe” Experiments must be controlled; they must have two set-ups that must differ by only one variable. The conclusion must be based on the data. variable any factor that could influence the result

A Controlled Experiment?

Scientific Method Observations Hypothesis Experimentation –Controlled (one variable changed at a time) –Collect data (quantitative and qualitative) –Analyze data (graph, statistics…trends) Form valid conclusion. After many experiments…form a theory.

Scientific Law vs. Scientific Theory Law of Gravity A theory tries to explain why or how something happens. A law states what happens. Theory of Gravity Atomic Theory Collision Theory of Reactions

Theory vs. Natural Law Scientific theoryNatural law Experiment Hypothesis analyze additional data analyze initial observations

Make observation Ask question Develop hypothesis Develop hypothesis Test hypothesis with an experiment Test hypothesis with an experiment Analyze data and draw conclusions Analyze data and draw conclusions Hypothesis IS supported Hypothesis IS supported Hypothesis is NOT supported Hypothesis is NOT supported Develop theory Develop theory Test hypothesis with further experiments Test hypothesis with further experiments Revise hypothesis Revise hypothesis Wysession, Frank, Yancopoulos, Physical Science Concepts in Action, 2004, page 8 Scientific Method

Results confirmed by other scientists – theory validate theory. Data do not support hypothesis hypothesis – revise or reject hypothesis Stages In The Scientific Method OBSERVING collecting data measuring experimenting communicating TESTING predicting experimenting communicating collecting data measuring THEORIZING constructing models predicting communicating PUBLISH RESULTS communicating FORMULATING HYPOTHESES organizing and analyzing data classifying inferring predicting communicating

Reviewing Concepts What is Science? How does the scientific process start and end? How are science and technology related? What are the branches of natural science? Explain the advantages and disadvantages of subdividing science into many different areas. Why do scientists seek to discover new laws of the universe?

Reviewing Concepts Using a Scientific Approach What is the goal of scientific methods? How does a scientific law differ from a scientific theory? What are scientific models useful? What are three types of variables in a controlled experiment? Does every scientific method begin with an observation? Explain.

Scientific Law Laws of nature never change. Charles’s Law V 1 V 2 T 1 T 2 =

Theories and Laws The Earth is flat… Speeding kills (Audubon, Germany); theory No explanation of why…but the theory is if you drive at 120 mph and crash, an ambulance won’t need to be called (only next of kin). seat belts save lives… LAW LAW: 65 mph and wear seat belt

Why Dinosaurs Disappeared Dinosaurs MeteorEarth Dust Cloud Moon is formed Ice Age - Glaciers RIP Meteor Crater Sun blocked Evidence… A theory…

The Original Metric Reference H2OH2O H2OH2O = 1 meter = 1 kilogram = 1 liter Length Mass Volume 1 kg 1/10 m 1/10,000,000

The Hellenic Market FireWater Earth Air ~ ~

Four Element Theory Plato was an atomist Thought all matter was composed of 4 elements: –Earth –Water –Fire –Air –Ether (close to heaven) ‘MATTER’ FIRE EARTHAIR WATER Hot Wet Cold Dry Relation of the four elements and the four qualities

Scientific Method and Law

Combustion & Phlogiston Phlogiston Theory Combustion Theory Burning Magnesium Metal in an Open Container Burning Magnesium Metal in a Closed Container Lighting a Bunsen Burner Flame Temperature Distribution

Phlogiston Theory (a) When an object burns it gives off a substance called phlogiston. (b) When the space surrounding the burning object is filled with phlogiston, the object will no longer be able to burn. Phlogiston theory of burning Dorin, Demmin, Gabel, Chemistry The Study of Matter, 3 rd Edition, 1990, page 4

Combustion Theory Modern theory of burning (c) When an object burns, it uses up a substance (oxygen) in the surrounding space. (d)When the space surrounding the burning object has too little oxygen in it, the object will no longer be able to burn. Antoine Lavoiser Dorin, Demmin, Gabel, Chemistry The Study of Matter, 3 rd Edition, 1990, page 4

Phlogiston Theory of Burning 1. Flammable materials contain phlogiston. 2. During burning, phlogiston is released into the air. 3. Burning stops when… …object is out of phlogiston, or …the surrounding air contains too much phlogiston.

Burning Magnesium Metal in an Open Container Dorin, Demmin, Gabel, Chemistry The Study of Matter, 3 rd Edition, 1990, page 77

Burning Magnesium Metal in a Closed Container Dorin, Demmin, Gabel, Chemistry The Study of Matter, 3 rd Edition, 1990, page 77