1.03 Scientific Method January 10 1

1.03 Scientific Method

Dr. Fred O. Garces Chemistry 111 Miramar College

1.03 Scientific Method January 10 2

Science and the meaning of life

-where did we come from? -why are we here? -where are we going?

Ever since humans had the ability to think and reason, they have been trying to answer some basic fundamental questions.

Philosophers and theologians have tried to answer these questions using logic, reasoning and faith.

Scientist uses a more strict procedure called the “Scientific Method”

http://video.idahoptv.org/program/history-science/

1.03 Scientific Method January 10 3

Scientific Method Scientist try to answer very basic questions by careful observations which is followed by postulating (proposing) an explanation.

To systematically accumulate this knowledge, scientist employ the Scientific Method.

Scientific method is the framework for gaining and organizing knowledge.

1.03 Scientific Method January 10 4

How and Why do Scientist employ the Scientific Method

As stated earlier, the scientific method is the framework for gaining and organizing knowledge. In this way,

Scientist tries to make sense as to why- • Bag of potato chips expand as you drive up mountain. • There is an ozone hole in the south pole. • Salt disappears when added to water.

Acquisition of knowledge requires solving problems. Scientist solve many problems, the systematic way this is done is called the “Scientific method”.

1.03 Scientific Method January 10 5

Steps of Scientific Method

1 Making the observations (Data) 2 Formulating a “Hypothesis” 3 Performing the experiment 4 Assembling a theory

If a theory is able to correctly predict facts that have not been previous observed, we begin to have confidence in our theory

an attempt to explain existing laws

Testing

Predictions

Scientific Hypothesis(testable assumption)

Questions

Observations (gathering of facts)

after a large body of facts has been gathered dealing with a certain topic, it is often possible to a makea general statement that summarizes these facts briefly. This generalized stated is called a law.

A hypothesis or theory is tested by making predictions as to what might be expected to happen in cases that have not been observed as of yet

Law - tells us what happens; a summary of observed behavior.

Theory - a theory (model) is our attempt to explain why it happens; an explanation of behavior.

1.03 Scientific Method January 10 6

Theory Vs. Law: An example Law tells what happens. Theory (model) attempts to explain why it happens Example: 1. Sun rise

2. digity (god)

3. telescope

1. stars planets around earth

2 Orbit shouldn't change

3. Copernicus/Kepler

Planets revolve around each other

Law of Gravity

The story of how society believed planets were once gods… to the theory of Relativity.

The story of the development of the Modern Atomic Theory.

1.03 Scientific Method January 10 7

Development of the Modern Atom Theory

How did man come up with the idea of the atom ?

It took ~2400 years from when it was first conceived to the time when there were actual experiments providing evidence of the atom existence.

1.03 Scientific Method January 10 8

History of Chemistry and development of the Atomic Model

History of Atomic Structure The timeline of the progression of the development of the Modern Atomic theory.

Empedocles

Zeno

DemoritusLeucippus

R. Boyle

A. Lavoisier

J. Proust

J. Dalton

-500 -250 0 250 500 750 1000 1250 1500 1750 2000-500 -250 0 250 500 750 1000 1250 1500 1750 2000

Atomic Theory Timel ine

1.03 Scientific Method January 10 9

Greeks View of Matter

Empedocles 440 BC Earth-Air-Fire-Water (supported by Aristotle)

Scholars during the Greek Golden Years thought about matter.

Several ideas presented were Zeno of Elea

400 BC Matter can be infinitely divided.

A foresight Hypothesis: Two bold scholars proposed a radical explanation –

Democritus - 399 BC Leucippuus - 400 BC Matter composed of indivisible particles called atomos.

1.03 Scientific Method January 10 10

For the next 2000 years … Alchemist (practiced pseudo fake-science) in which they tried to convert lead (Pb) into gold (Au). Numerous failures resulted in forcing these alchemist to writing down their experiment procedure. This led to the lab notebook as we know it today.

A lot of their experiments consisted of systematically extracting metals from ore. This is known as metallurgy.

1.03 Scientific Method January 10 11

Break down the Greek’s Model

The Skeptical Chemist. In 1500, Sir Robert Boyle performed detailed experiment with gases. In his work, he found out that matter broke down to fundamental particles and no further. He formulated the idea of elements and initiated the break down of the Greek's model of the matter. Matter is not made of earth, air, fire and water.

He published the book;

the Skeptical Chemist.

1500 Robert Boyle

1.03 Scientific Method January 10 12

Careful measurements is very important. 1700 Antoine Lavoisier Father of modern chemistry (Law of conservation of mass.) Lavoisier made very careful measurements and concluded that mass is neither created nor destroyed. At the time, it was thought that when a substance was burned, the ashes were lighter than the starting material and therefore matter (stuff) could be destroyed; it is not conserved. Lavoisier however, did experiments in an enclosed container and noted that indeed matter is not destroyed, it is only changed. He argued mater is conserved.

1.03 Scientific Method January 10 13

If matter cannot be destroyed, what is the essence of matter ?

What are the classifications of matter? elements, compound, mixture, ...

What are the three (actually 4) states of matter? Solid, Liquid, Gas

How can the physical & chemical properties be distinguish in matter? Identity retain vs. new identity.

en.wikipedia.org/wiki/Higgs_boson

1.03 Scientific Method January 10 14

The Theory of the atom today: Planetary Model...Quantum Chem

1.03 Scientific Method January 10 15

Famous Last Words...

Albert Einstein "No amount of experiment can prove me right; a simple experiment may at any time prove me wrong."

In summary,

The scientific methods was, and is, responsible for developing the model of the atom and matter as we know it today.