Download Chapter 2 review key

Chapter 2 Review Sheet Key
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Answer each question as thoroughly as possible, as most of these will have more than question asked about it
on the test. For example, questions 1 and 2 below, if well-answered, cover every item on page one of the test.
Also, check out the review and standardized test prep at the each of the chapter.
There are 3 essays on the test. You must use complete sentences, proper grammar, punctuation, and spelling.
You need to include explanations or examples. This portion of the test is worth 16 points. Possible discussion
topics include:
Structure of an atom
The pH scale, acids and bases The molecules of life
The properties of water
Isotopes
Enzymes
Diversity of organic compounds
Solutions and suspensions
Chemical bonds
Ten of the following words will appear as “fill-n” items on the test. These will NOT be listed on the test, so get
to know them!
-ase
Atom
Activation energy
Bond energy
chemical
compound
cation
energy level
electrons
[H]+ ions
[OH]- ions
CO2
H20
covalent
Van der Wals forces
ionic
water
protons
neutrons
nucleus
macromolecule
polymers
monomers
polarity
Study your periodic table! Make sure you can identify the correct number of subatomic particles in any element
given to you (see page A-24 at the back of your book). Know the properties of each subatomic particle and
where each is located in an atom. Ex: On the periodic table, characteristics of each element are predictable.
for example, carbon (carbon-12, that is) has the atomic # 6 because it has 6 protons. It has an atomic mass of
12 amu’s because it also has 6 neutrons. These particles are located in the nucleus and make up the entire
atomic mass. There are 6 electrons orbiting around the nucleus, and these don’t add to the mass because
they are 1/1840th the size of a proton. They do balance the positive charges in the nucleus though, which is
why atoms are neutral unless they gain or lose and electron in the formation of ions.
1.
What is an isotope? Use specific examples. One of the most well-known elements having isotopes is
carbon. Carbon-12 is the most common isotope, is not radioactive, and appears on the periodic table along
with the other most common isotopes. It has an atomic mass of 12, because it has 6 protons and 6 neutrons
in the nucleus. Each of these has a mass of 1 atomic mass unit, which is why its atomic mass is 12. Carbon-14
is equally well-known. It is radioactive, and decays, becoming nitrogen-14. Carbon-14 still has 6 protons in
the nucleus (or it would not be carbon…it would be some other element!), but has 8 neutrons instead of six.
This is why it has a mass of 14 amu’s. (6 protons + 8 neutrons=14 nucleons)
3.
Draw a water 3-D water molecule showing its polarity.
O_
H+
H+
4.
How are compounds different than elements? Elements are composed of one type of atom, with
characteristic properties (solid, liquid, gas, density, melting point, etc.) Compounds are composed of more
than one type of atom, with physical and chemical properties different than any of the elements of which it is
made.
5.
Differentiate between ionic and covalent bonds, giving an example of each. Ionic bonds occur when
electrons are transferred between atoms. One element loses electrons, and another gains it. This creates an
imbalance between the positively charged nucleus and the electrons’ orbit. For example, when table salt is
formed, a sodium atom gives up its one valence electron and becomes positively charged (11 protons, 10
electrons). Chlorine accepts this electron and becomes negatively charged (17 protons, 18 electrons. These
opposite charges pull the ions together. In a covalent bond, which can be polar or nonpolar, electrons are
shared between atoms. Ethane, C2H4, is a carbon compound that is nonpolar. H20 is a polar covalent bond.
6.
Which electron(s) are involved in forming chemical bonds? Valence electrons
7.
Differentiate between a solution and a suspension. Both are mixtures. In a solution that is not
saturated, the solute dissolves so that it is not visible in the solvent. In a suspension, the particles of the
solute can be observed. A cell would be a good example of a suspension. If we add salt to a pot of boiling
water, is a solution.
8.
Describe the structures of each of the molecules of life.
Carbohydrates—small or large carbon compounds with the empirical formula CH20. Glucose is the
primary source of energy for most living things. Sugars and starches (large molecules made from simple
sugars) are carbohydrates, and may be structural, such as the cellulose in plants.
Proteins—are POLYMERS composed of MONOMERS called amino acids, of which there are 20.
Proteins can be structural. They can also control the rate of chemical reactions (enzymes), move substances
in and out of cells, and help fight disease.
Lipids—are better known as fats, and are a stored source of high energy (twice as much as carbs or
proteins). They are also found in cell membranes and as protective coverings. Fats, oils, waxes and some
steroids are lipids.
Nucleic acids—molecules that store and transmit genetic information, DNA and RNA are POLYMERS
composed of MONOMERS called nucleotides. Nucleotides contain nitrogen-containing bases that determine
the structure of each gene.
9. Identify the reactants and products in this equation: 6 CO2 + 6 H20  C6H12O6
CO2 + H20 are the reactants; C6H12O6 is the product
10.
Differentiate between acids and bases. Acids and bases are categorized based on their contribution to
a solution and their position on the pH scale, which goes from 1-14. Acids fall between 1 and 7 (neutral) and
are substances that increase the H+ concentration in solution. Bases fall between 7-14, and increase the OHconcentration in solution.