2. The Scientific Method
Science is a cyclic process to determine the best
explanation of a phenomena.
observe /
experiment
? explain
3. The Scientific Method
Explanations, called hypotheses, are “tested”
with controlled experiments in a laboratory,
and/or systematic collection of data in the
uncontrolled ‘real world.’
more experiments
experiments repeated experiments
speculation Hypothesis theory
real world repeated real
observations world observations
more real world observations
4. The Scientific Method
Usually, multiple explanations are
possible and each needs to be evaluated.
? Explanation 1
Explanation 2
Explanation 3
5. For example: CO2, CH4, and the transmission of
heat and light through air
Carbon dioxide (CO2) and methane (CH4) hinder the
transmission of heat (long wave radiation) through air
Ch4 Co2
long wave radiation
6. For example: CO2, CH4, and the transmission of
heat and light through air
• The temperature of the Earth has warmed as the
concentration of CO2 and CH4 have increased
• “Proof” that human contributions of those gasses are the
cause is not possible. It will never be possible, even if all
the ice melts.
Co2
Ch4
other factors
(volcanoes,
planetary cycles…)
7. “Proof” is in the eye of the beholder
• Science supports or refutes hypotheses with
evidence.
• Scientific evidence is
ALWAYS subject to
interpretation.
• It is the weight of multiple lines of evidence
that is sometimes accepted as “proof.”
8. plate
tectonics…
… is the best explanation of multiple lines of evidence, e.g.:
– earthquakes along lines of contact
– sea floor spreading
– rock record of organism interactions
… has been extensively studied and supported
… is accepted as theory
10. Technology
• The application of knowledge for practical purposes;
the modification of materials to meet human needs.
• Cooked food, smelted ores, alcohol, pharmaceuticals.
11. Philosophy
• The application of scientific theory, developed over
time with extensive experimentation and observation,
to explain the behavior of matter.
• Plate tectonics, evolution, global warming.
12. A very brief history of science
Greek philosophers (~2500 yrs ago)
13. history of science, continued
• Aristotle (384 – 322 BC)
explained matter as composed of four elements:
• Air
• Fire
• Water
• Earth
in different combinations with variable temperature and moisture
content – to yield solids, liquids, and gases with different
properties.
• Dominated for ~2000 years
14. history of science, continued
Alchemy (500-1600 AD)
– A mystical blend of chemistry,
magic, and religion
– Gold, seen as the purest form of
matter, was the goal
– Several metals are still identified
with their planetary symbol, first
assigned by alchemists
– Planted the roots of
experimental science, especially
chemistry
15. Other Chemistry GREATS
Robert Boyle – Boyle’s Gas Law (which lead to the Ideal Gas Law)
http://en.wikipedia.org/wiki/Boyle%27s_law
In a closed system with fixed mass and temperature, pressure and volume are
inversely proportional—meaning that as one goes up, the other goes down.
Antoine Lavosier – Law of the Conservation of Mass
http://en.wikipedia.org/wiki/Conservation_of_mass
In a closed system, mass is neither created nor destroyed, though it can take
different forms.
Robert Dalton – Dalton’s Atomic Theory
http://en.wikipedia.org/wiki/John_Dalton#Atomic_theory
• All matter is composed of tiny, indivisible particles called atoms.
• All atoms of a particular element are identical, but the atoms of one element differ
from the atoms of any other element.
• Atoms of different elements combine with each other in certain whole-number
proportions to form compounds.
• In a chemical reaction, atoms are rearranged to form new compounds; they are not
created, destroyed, or changed into atoms of any other elements.
All links IYW
16. history of science, continued
Learn more about Alchemy
http://www.rsc.org/chemsoc/visualelements/pages/alchemist/a
http://en.wikipedia.org/wiki/Alchemy
And the history of Chemical Science
http://en.wikipedia.org/wiki/History_of_chemistry
All links IYW
Editor's Notes
Hello. This is the first screencast and is intended to provide some basic background on science and chemistry that is not included in the book. An essential understanding of the scientific method is critical for all citizens in the modern world and this screencast briefly review the benefits and limitations of science before we get started with the semester. The objectives for this week are for you to be able to: Briefly describe the scientific method including an essential history of chemical science; Appreciate the values and limitations of science; Begin to construct a framework for understanding chemistry’s role in modern society.
Science is cyclic process of hypothesis development and testing
A phenomena, problem, or question is identified and reasonable explanations/answers are formulated. The key to the scientific method is figuring out how to test those hypotheses. Tests are meant to check the limits of the hypothesis as a feasible explanation. In a laboratory, conditions can be controlled and experimental tests can establish clear findings relating one phenomena to another. However, in the real world, we cannot control conditions so much as we can recognize them. Observational studies are inherently weaker than experimental studies because of that lack of control, but in the real world, observation is , EXAMPLES!
All reasonable explanations must be considered. Most often, multiple factors are contributing to a particular outcome and the real puzzle is determining the relative weight of each factor. The puzzle is further complicated if those factors (possible explanations) influence each other. For example, what killed the dinosaurs? Was it just an asteroid impact? More research has found that dinosaurs were already on the decline. The weather changing and mammals were stealing eggs and otherwise impairing dinosaur populations. This case is a good example of how there are usually not just multiple possible explanations, but truly a combination of factors that make clear “cause and effect” relationships elusive.
In the laboratory, it can be clearly demonstrated that the concentration of carbon dioxide (CO 2 ) and methane (CH 4 ), each have an unusual ability to hinder the transmission of heat (long wave radiation) through air.
In the real world, we can see that the surface temperature of Earth has warmed as the concentrations of CO 2 and CH 4 have increased. There is extensive evidence that the concurrence of these trends is not just “coincidental, ” but other things have changed at the same time, so a definitive conclusion that human caused contributions of those gasses are totally responsible is not possible, or even likely.
Scientific evidence can be strong or weak, and it can support of refute particular ideas about the world, but it always needs to be interpreted. Science is intended to support or refute hypotheses, allowing scientists to continually improve their understanding of a phenomena. The truth is that science can never “prove” that a hypothesis will hold in every situation, every time.
“ Theories” such as plate tectonics grow and change as scientific evidence accumulates and the general explanation is not refuted but rather refined, and widely considered “proven.”
Science is used in two realms: Technological (factual) Philosophical (theoretical)
Technology is based on fact – it is t he application of knowledge for practical purposes; the modification of materials to meet human needs. Cooked food, smelted ores, alcohol, pharmaceuticals.
Philosophy is based on theory – it is the a pplication of theory, developed over time with extensive experimentation and observation, to explain the behavior of matter.
Greek philosophers (~2500 yrs ago) speculated and observed but did not experiment or “test” what they believed.
Aristotle (384 – 322 BC) explained matter as composed of four elements: Fire Water Air Earth in different combinations with variable temperature and moisture content – to yield solids, liquids, and gases with different properties. Dominated for ~2000 years
Alchemy (500-1600 AD) A mystical blend of chemistry, magic, and religion gold was thought to be the purest form of matter different methods were used to (try to) produce gold… none succeeded, but many substance were identified techniques, such as extraction and distillation, were developed and interest in human health was sparked : “internal alchemy” Several metals are still identified with their planetary symbol, first assigned by alchemists Planted the roots of experimental science, especially chemistry
We are skipping a lot of important detail, but these great thinkers were ahead of their time and paved the way for modern chemistry. We’ll learn more about these principles and the errors within as we learn more about atoms, and how they make substances next week, and we’ll be hearing about gas laws and the conservation of mass later in the term.
