Name______________________________
Date_____________________
ALE#1
1. Diamonds are forever, but are theories forever too? Explain in light of your
knowledge of the scientific process.
No. Theories remain until they are proven false. There is always the possibility,
however slight, that a new experiment or observation may bring the theory into question.
However, many current scientific theories have been tested and retested thousands of
times, with outcomes that always support the theory.
2. Can you use the scientific method to prove that Abraham Lincoln was the 16th
president of the United States? Explain your reasoning.
No. Abraham Lincoln was the 16th president. This is a FACT. It cannot be tested,
measured, or proven false.
3. Distinguish between and explain how scientists use each of the following: i.)
scientific theory, ii.) Hypothesis and iii.) Scientific law. Now explain how the
common person uses the word ‘theory” in every day usage.
i) A scientific guess about the answer to a question
ii) A hypothesis that has never been proven wrong, after extensive experimentation.
They are broadly accepted in the scientific community
iii) An observable phenomena that is invariably true. We do not arrive at laws
through scientific method.
Scientists use theories as the basic framework within which they derive their hypotheses.
For example, evolution is a scientific theory. It has been tested and retested and has
always been proven true. Within this theory, scientists derive hypotheses. For example,
one hypothesis might be: the pygmie humanoid remains recently found in Indonesia are
not of the species Homo sapiens, but instead descended from the more primitive Homo
erectus. This hypothesis assumes that the theory of evolution is true. DNA evidence can
be used to provide the experimental data to support or reject this hypothesis.
The word “theory” is used in everyday language to mean “a guess.” For example, I have
a theory about why students’ grades are poorer in spring: the weather gets better and they
spend less time studying.” Within the method of science, this is actually a hypothesis,
not a theory.
4. Design a controlled experiment to test the effect that age may have on the grade
point average of GRCC students. Include your hypothesis, prediction, variables,
control, and procedure.
hypothesis: age affects the grade point average of GRCC students
prediction: students over 30 years old have higher grade point averages than students
under 30 years old.
independent variable: age
dependent variable: grade point
experimental group: those over 30
control group: those under 30
controlled variables: all students attend GRCC.
procedure: all grade point averages for students over 30 years old will be averaged at the
end of the quarter. all grade point averages for students under 30 years old will be
averaged at the end of the quarter.
5. Darwin’s theory of natural selection is occasionally criticized by the layperson as
being “only a theory.” Comment on the validity of this statement in light of what you
know about the scientific method and how a hypothesis becomes a scientific theory.
Hint: Think about how our society uses the term theory, versus the scientific
meaning of a theory.
The layperson may say that natural selection is “only a theory”. What they mean is that
natural selection is just a guess. Those of us whom have studied science know that
natural selection is a scientific theory. This means that natural selection has been tested
and retested many times, in many different settings and places and times. There are
currently no other scientific theories to explain the divergence of species.
6. Often if a person can visualize a concept they will understand and remember the
concept. Here are some terms that are used regularly in chemistry and are important
to understand clearly. Create a diagram (or diagrams) that would help someone
understand what is meant by the following terms: matter, atoms, elements, chemical
bonds, molecules, and compounds.
answers will vary
7. Atoms consist primarily of three kinds of subatomic particles. Identify and describe
particles by completing the chart below.
Name of subatomic particle
electron
proton
neutron
Electric charge
negative
positive
neutral/none
8. Atoms are always electrically neutral, that is they are not positively or negatively
charged. From this fact, how do the number of protons compare to the number of
electrons in an atom?
They are equal in number
9. A lump of the element gold has different properties than a lump of the element
carbon. An atom of gold has different properties than an atom of carbon. How can
atoms of gold and carbon have different properties if all atoms consist of the same
subatomic particles? What determines the identity of an atom?
The number of protons determines the property of the atom or element. The number of
electrons can change (the atoms becomes an ion), and the number of neutrons can change
(the atom becomes an isotope), but the atom is still the same element. The # of protons
cannot change. You cannot change one element into another.
10. What is an ion? Provide several examples of some ions using chemical formulae and
written names.
An ion is an atom that has gained or lost an electron, resulting in a net positive or
negative charge. An example is the chloride ion: Cl- that becomes part of table salt: NaCl
by creating an ionic bond with a sodium ion: Na+.
11. Water consists of tiny particles called molecules. Each water molecule contains
___2__ atoms of hydrogen __________covalently_________ bonded to
____one____ atom of oxygen. In the space below draw one water molecule and label
the bonds. Your drawing should have an oxygen atom attached to two hydrogen
atoms. The bonds should be labeled as covalent bonds. Use figure 2.9 in your text as
a guide.
12. Distinguish between the following kinds of chemical bonds: covalent bond, hydrogen
bonds, and ionic bonds, giving an example of each.
An ionic bond forms when a positive ion is attracted to a negative ion. Example: Na+
plus Cl- makes NaCl.
A covalent bond forms when two atoms share electrons in their outermost shell in order
to fill that shell. Example: hydrogen gas, H2. Each H atom has one electron in its
outermost shell, which can hold a total of 2 electrons. By sharing their atoms, both atoms
can complete their shell.
Hydrogen bonds are electrical attractions between the slightly negative end of a molecule
with a hydrogen ion (H+), as in water. The oxygen end of a water molecule is slightly
negative and is attracted to the slightly positive hydrogen end of another water molecule.
13. Whirligig beetles are small insects that run around on water as if it were a hard
surface, and they stay completely dry. How are they able to do this?
Hydrogen bonding creates surface tension in water. The whirligig beetle is not massive
enough to break the force of this surface tension.
14. List the four life-supporting properties of water that result from the tendency of water
molecules to form hydrogen bonds. Discuss how each of these properties is
important to life.
Versatility of water as a solvent – it can dissolve many substances, such as salt. This is
important in the osmoregulation of our internal body fluids/organs.
Water’s cohesive nature. This is especially important in the movement of water withing
plants and trees.
Water’s ability to moderate temperature. Since most of our planet is covered in water,
the planet’s temperate remains in the moderate range, that is most favorable to life.
Ice floats – the density of ice is less than water, which means it will float on top of liquid
water. This insulates the water beneath, preventing it and all the organisms within it from
freezing.