Distance Chemistry 100X

The scientific method

The Scientific MethodScience is a cyclic process to determine the best

explanation of a phenomena.

explain observe / experiment ?

The Scientific MethodExplanations, called hypotheses, are “tested” with controlled experiments in a laboratory, and/or systematic collection of data in the uncontrolled ‘real world.’

Hypothesis

more experiments

more real world observations

experiments repeated experiments

real worldobservations

repeated real world observations

speculation theory

The Scientific Method

Explanation 1Explanation 2Explanation 3?

Usually, multiple explanations are possible and each needs to be evaluated.

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

Co2Co2Ch4

Ch4

long wave radiation

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.

Co2Co2 Ch4

Ch4

other factors(volcanoes, planetary cycles…)

• 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.”

“Proof” is in the eye of the beholder

… 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

plate tectonics

…

IMAGE SOURCE http://asiasociety.org/files/issn-science2.jpg

Technology

• The application of knowledge for practical purposes; the modification of materials to meet human needs.

• Cooked food, smelted ores, alcohol, pharmaceuticals.

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.

A very brief history of science

Greek philosophers (~2500 yrs ago)

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

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

history of science, continued

Robert Boyle – Boyle’s Gas Law (which lead to the Ideal Gas Law)http://en.wikipedia.org/wiki/Boyle%27s_lawIn 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 Masshttp://en.wikipedia.org/wiki/Conservation_of_massIn a closed system, mass is neither created nor destroyed, though it can take

different forms.

Robert Dalton – Dalton’s Atomic Theoryhttp://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.

Other Chemistry GREATS

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Learn more about Alchemy

http://www.rsc.org/chemsoc/visualelements/pages/alchemist/alchemy.html

http://en.wikipedia.org/wiki/Alchemy

And the history of Chemical Science

http://en.wikipedia.org/wiki/History_of_chemistry

history of science, continued

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