Introduction to the
• By the end of this lesson, you MUST be able
• General Learning Outcome:
• Describe ideas used in interpreting the chemical nature
of matter, both in the past and present, and identify
example evidence that has contributed to the
development of these ideas
• Specific Learning Outcome:
− demonstrate understanding of the origins of the periodic
− distinguish between observation and theory, and provide
examples of how models and theoretical ideas are used in
What do we mean by a
• A chemical element is matter,
all of whose atoms are alike in
having the same positive charge
on the nucleus and the same
number of extra-nuclear
Where do/did the
elements come from?
• They exist in
How do we know
anything about them?
• Greek Philosophers investigating matter
• Early alchemists
• Scientific Revolution:
• Sir Francis Bacon
• Robert Boyle
• Antoine Lavoisier
• John Dalton
Where do the names of the
chemical elements come
• many sources:
• mythological concepts or characters
• places, areas, or countries
• properties of the element or its
• inability to combine
• names of scientists
• some miscellaneous / obscure names
• Using the chart provided by the
teacher, summarize the
contributions of each to the
development of current
chemical element theory.
• DUE DATE: ____________________
How have all of these ideas
come together to form our
modern view of chemistry?
• Scientists have been striving for centuries
to EXPLAIN matter!
• Observations: how scientists gather the
information they need to formulate theories and
• Theories: imaginings; creative ways to try to
explain why something happens
• Laws: descriptions and summaries of what has
been observed happening
• Science begins with observations of nature
• Anything you see, hear, smell, taste, or touch
is an observation
• Observations are performed by people, who
• senses are not as fine-tuned as people like to
• People are easily fooled - when they really want
something to happen, they often observe it
happening, whether it really happens or not!
How do you gain confidence
that your observation is
• tell others about it
• If other scientists can make the same
observation, we can be more confident
that an observation is correct
• Therefore, scientific observations must
• Otherwise, there is no way to tell if the
observation is correct.
How can we make our
• Formulate testable theories
• How can we do this?
• Experimental Design
• Make an observation
• Ask a question to guide research
• Create a hypothesis
• Test the hypothesis (with experiments)
• Make your conclusions
• Was your hypothesis correct?
• If so, move to theory
• Was your hypothesis incorrect?
• If not, start all over!
• Create a theory (based upon hypothesis – correct /
• Revisit/re-design/re-formulate as necessary
Example: The Columbus
Observation: as I look toward the horizon, it appears as if the Earth if
• Question: Is the Earth Round?
• Hypothesis: I predict that the Earth is round!
• Experiment: sail around the Earth in one direction until you return to the
• Conclusion: My hypothesis is correct!
• Theory: the Earth is round! One can sail around the Earth, heading in 1
direction, beginning at one point and returning to that same point
• What are some other factors that could account for my conclusion?
• I'd better give some strength to my theory…
• Other captains/vessels can (and should) make the same journey to
substantiate my conclusion) as new technology arises (satellite images,
space travel) we can look down onto Earth and see that it is in fact
• In small groups, read pages 460-463 in
appendix of your text.
• Define all bold terms
• Clarify the difference between
• Qualitative and quantitative observations
• Complete the Instant Practice
Questions on page 463
• Due date: _____________________