Chapter 2 Study Guide
Key terms and definitions to know:
1. Atom- the basic unit of matter.
2. Electron- a negatively charged, subatomic particle of an atom. (-)
3. Proton- a positively charged, subatomic particle of an atom. (+)
4. Neutron- a neutral subatomic particle of an atom (carry no charge).
5. Nucleus- the center of an atom that contains protons and neutrons.
6. Element- a pure substance that consists of only 1 type of atom; Represented by a 1 or 2 letter symbol
Ex: The element carbon’s symbol is C
7. Isotope- atoms of the same element that have different numbers of neutrons.(Protons are always the
same)
8. Mass number (or atomic mass)- the total number of protons and neutrons in the nucleus.
9. Atomic number- the total of protons in an atom (never changes).
10. Compound- a substance formed by the chemical combination of 2 or more elements in definite
proportions.
11. Ionic bond-bonding that occurs when 1 or more electrons are transferred from 1 atom to another.
12. Ions- positively and negatively charged atoms that result from ionic bonding.
13. Covalent bond- bonding that forms when electrons are shared between atoms.
14. Molecule- the structure that results from a covalent bond; the smallest unit of most compounds.
15. van der Waals forces- a slight attraction between oppositely charged regions of nearby molecules. (Gecko
feet sticking to a wall)
16. Polarity (polar molecule)- an uneven distribution of electrons between atoms; causes 1 end of a molecule
to be slightly positive, and 1 end slightly negative. (Water is a polar molecule)
17. Cohesion- attraction between molecules of the same substance; water is very cohesive.
18. Adhesion- attraction between molecules of different substances. (capillary action-example-water rising
from roots of plants into leaves and stems)
19. Mixture- material made of 2 or more elements or compounds that mix physically, but not chemically. (exsalt and pepper stirred together, or water and sugar)
20. Solution- a mixture of 2 or more substances in which the molecules of the substance are evenly
distributed.
21. Solvent- a substance in which something is dissolved to make a solution. (water and sugar-water is the
solvent)
22. Solute- the substance that is being dissolved to make a solution. (water and sugar-sugar is the solute)
23. Suspension- a mixture of water and nondissolved material. (blood)
24. pH scale- determines if a substance is an acid or base by measuring the concentration of Hydrogen ions in
solution. (pH up to 7= acid, pH above 7= base, pH of 7 is neutral)
25. Acid- a compound that forms Hydrogen (H+) ions in solution and has a pH below 7.
26. Base- a compound that forms Hydroxide (OH-) ions in solution and has a pH above 7.
27. Buffers- weak acids or bases that can react with strong acids or strong bases to prevent sharp, sudden
changes in pH.
28. Macromolecules- “giant molecules” made from thousands of smaller molecules.
29. Monomer- small unit that can fit together with other small units to form a polymer.
30. Polymer- large compound formed from many monomers.
31. Carbohydrates- macromolecule made up of carbon, hydrogen, and oxygen, usually in a 1:2:1 ratio; main
energy source used by living things; also used for structural purposes. (sugars and starches)
32. Monosaccharide- a single sugar molecule. (glucose, galactose, fructose)
33. Polysaccharide- a large sugar molecule formed from many monosaccharides. (cellulose, glycogen)
34. Lipids- macromolecule made mostly from carbon and hydrogen; usually not soluble in water, includes fats,
oils, and waxes; used to store energy
35. Nucleic acid- macromolecules including hydrogen, carbon, oxygen, nitrogen, and phosphorus; assembled
from monomers called nucleotides; store and transmit hereditary or genetic information. (DNA and RNA)
36. Nucleotide- monomer of nucleic acid, consists of 3 parts: a 5-carbon sugar, a phosphate group and a
nitrogenous base.
37. Proteins- macromolecule that contains carbon, hydrogen, oxygen, and nitrogen; polymers of molecules
called amino acids; controls the rate of reactions and cell processes, forms bones and muscles, transports
substances in and out of cell.
38. Chemical Reaction- a process that changes, or transforms one set of chemicals into another.
39. Reactants- the elements or compounds that enter into a chemical reaction.
40. Products- the elements or compounds produced by a chemical reaction.
41. Activation energy- energy that is needed to get a reaction started.
42. Catalyst- a substance that speed up a chemical reaction; lower activation energy.
43. Enzyme- proteins that act as biological catalysts; speed up chemical reactions; very specific, catalyzing only
1 reaction
44. Substrate- the reactants (elements or compounds that enter into reaction) of enzyme-catalyzed reactions;
bind to enzyme like a lock and key.
Section 1 : The Nature of Matter
1. Know the structure of an atom.
2. Atomic Number= the number of protons in an atom (never changes)
3. Atomic Mass= the number of protons + neutrons
4. What is an isotope?
An isotope is an atom of the same element that differs in the number of neutrons. Proton and electron
number always stays the same. Isotopes have the same number of electrons, so they have the same chemical
properties.
5. What is a compound? A compound is the chemical combination of 2 or more elements in definite
proportions. Example: sodium and chlorine combining to make table salt.
6. What are the 2 main types of chemical bonds?
1. Ionic bond- electrons are transferred from 1 atom to another.
2. Covalent bond- electrons are shared between 2 atoms.
7. What is a molecule? A molecule is the smallest unit of most compounds.
8. What are van der Waals forces? A slight attraction of oppositely charged regions of nearby particles.
Example: Gecko gripping onto smooth, verticle surfaces
Section 2: Properties of Water
1. What does it mean if a water molecule is polar? A polar molecule has an uneven distribution between of
electrons, causing one end to be slightly negative and one end to be slightly positive. (Like a magnet with
poles, oppositely charged ends of molecules of water are attracted to each other)
2. What is an example of a hydrogen bond? The attraction between the hydrogen atom (slightly positive in
charge) of 1 water molecule and the oxygen atom of another molecule (slightly negative in charge).
3. What is the difference in cohesion and adhesion? Cohesion is the attraction between molecules of the
same substance (Examples: water, which is very cohesive, allows some insects to walk on water and the
beading of water on smooth surfaces). Adhesion is the attraction between molecules of different substances
(Examples: the rising of water into a straw in a glass, the movement of water from a plant’s roots to stems and
leaves which is called capillary action).
Cohesion
Adhesion
4. Define mixture. A mixture is material composed of 2 or more elements that are physically mixed but not
chemically mixed. Example: salt and pepper mixed together; kool aid, sugar, and water mixed together
5. What are the 2 types of mixtures that can be made with water? How are they different? What is an
example of each? The 2 types are solutions and suspensions.
1. Soutions are mixtures of 2 or more substances in which the molecules of the substance are evenly
distributed. An example of a solution is sugar dissolved in water. Water is the solvent, sugar is the
solute.
2. Suspensions are mixtures of water and nondissolved material. An example of a suspension is blood,
which contains cells and other undissolved particles.
6. What is the pH scale and what does it measure? The pH scale is a measurement system that indicates the
concentration of H+ ions in solution. It decides whether or not a substance is an acid or a base.
7. What is an acid? What is a base? An acid forms Hydrogen (H+) ions in solution and has a pH below 7.
Examples include: stomach acid, lemon juice, and rainfall. A base (or alkaline) produces hydroxide (OH-) ions in
solutions and has a pH above 7. Examples include: soap, ammonia, and bleach.
8. What is a buffer and what is it’s purpose? A buffer is a weak acid or weak base that reacts with strong acids
or strong bases. It’s purpose is to prevent sharp, sudden changes in pH.
Section 3: Carbon Compounds
1. What is unique about carbon? Carbon compounds are found in all living things. Carbon can also bond to
other carbon compounds, giving it the ability to form chains that can almost be unlimited in length. Carbon
has the ability to form millions of different large and complex structures, making it very versitile.
2. What is a macromolecule? A macromolecule is a “giant molecule” formed by a process called
polymerization.
3. What is a monomer? What is a polymer? A monomer is a small unit that can fit together with other small
units to form a polymer. A polymer is a large compound made of many monomers. Remember these prefixes:
Macro=large
Mono=one
Poly=many
4. What are the 4 groups of organic macromolecules found in living things? The 4 groups are: carbohydrates,
lipids, nucleic acids, and proteins.
5. What is a carbohydrate? What is a monosaccharide and a polysaccharide? A carbohydrate is a compound
made up of hydrogen, oxygen, and carbon. Living things use carbohydrates as their main source of energy. A
monosaccharide is a single sugar molecule and a polysaccharide is a large sugar molecule made of many
monosaccharides.
6. What is a lipid? A lipid is a molecule made mostly from carbon and hydrogen. They are used to store
energy, and some are used for biological membranes. Lipids include fats, waxes, oils, and steroids.
7. What is a nucleic acid? A nucleic acid is a molecule containing hydrogen, carbon, oxygen, phosphorus, and
nitrogen. They are assembled from monomers called nucleotides. Nucleic acids store and transmit hereditary
or genetic information. (DNA and RNA)
8. What is a protein? A protein contains nitrogen, carbon, hydrogen, and oxygen, and is a polymer of
molecules called amino acids. Proteins control the rate of reactions and regulate cell processes, are used to
form bones and muscles, transport substances into or out of a cell, or help fight disease.
Macromolecules
Biological
Function
Macromolecule
Lipids
Proteins
Examples
(building block)

Carbohydrate
Monomer
 Glucose
short term
energy storage
Monosaccharides

Structural
support in plants
 long term energy
storage
 chemical
messengers
 Insulation
 Protects soft
organs
 catalyze chemical
reactions
 Structural
components(traits
)
 Transport
molecules
 Body defense
 Signaling
 Storage
1:2:1 ratio of C:H:O
Polysaccharides:
 starch (plants)
 glycogen(animals)
 cellulose (cell wall)
Fatty Acids




Amino Acids


- contain C, H, O, and N
.

Fat
Oil
Wax
hormones
Enzymes
Hemoglobin – transports O2
in blood
Insulin – regulates blood
sugar
Nucleotides
Nucleic Acids

Carries genetic
information


DNA
RNA
Section 4- Chemical Reactions and Enzymes
1. What is a chemical reaction? What are the parts of a chemical reaction? A chemical reaction is a process
that changes, or transforms, one set o chemicals into another. The elements of compounds that enter into the
reaction are called reactants. The elements or compounds produced by a chemical reaction are called
products.
2. Know that chemical reactions always involve changes in the chemical bonds that join the atoms in
compounds. Also, that a chemical reaction will either absorb, or give off energy.
3. Energy changes are important factors in whether or not a chemical reaction will occur. Chemical reactions
that release energy often occur spontaneously. Chemical reactions that absorb energy will not occur without a
source of energy.
4. What is activation energy? Activation energy is the energy that is needed to get the reaction started.
Activation energy is a factor in whether the overall chemical reaction releases energy or absorbs energy.
5. What is a catalyst and how does it affect activation energy? A catalyst is a substance that speeds up the
rate of a chemical reaction. Catalysts lower a reaction’s activation energy.
6. What is an enzyme? An enzyme is a protein that acts as a biological catalyst. Enzymes speed up chemical
reactions and lower activation energy.
7. Know that enzymes are very specific and generally catalyze only 1 chemical reaction. The enzymes name is
usually derived from the reaction it catalyzes. Example: The enzyme lactase, catalyzes the reaction that breaks
down lactose (milk sugar).
8. What is a substrate in an enzyme-catalyzed reaction? The substrate is the reactants in these reactions.
There is an active site where the substrate and enzyme bind like a lock and key. Enzymes can be affected by
temperature and pH. Enzymes can be turned off and on by proteins, and play essential roles in the body’s
chemical pathways.