BIOCHEMISTRY Worksheet #1 (Module 2)

These exercises help to “cement” the information in our brain so we can use that learning in our other tasks, both
in life and in this course. When we exercise our thinking outside of reading and speaking, we remember better and
accomplish more.

Goal of this activity

To solve problems with atoms, molecules, and chemistry that are critical to maintaining life (biology)

Steps for Success with this activity

1. Look through the entire document, making note of what you have seen or heard previously. Rely on your
prior learning! Use that learning to build more.

2. Please remember that biology makes chemistry EASY! We learn applications of the chemical laws that seem
difficult. Actually, learning bio-chemistry will help you succeed in chemistry!

3. Work through the problems in any order.

a. Have the Periodic Table document open as you work.

b. Typically, the problems with the Periodic Table are important to understand prior to the work with
carbon molecules, but do them in the order that makes sense to you.

c. Sometimes starting with the last page will help you see the reason to learn the 1st page.

4. Healthy frustration is the foundation of real learning, so be patient with yourself and ask your professor if
you have questions. Bring all questions and inconsistencies to the Tech Live sessions.

TOPICS and ACTIVITIES

Compare atoms, elements, chemical bonds, and molecules (OpenStax, Concepts of Biology, section 2.1)

1. Define the following terms:

a. Matter – Matter is anything that has mass and occupies space. It can exist in various forms, including
solid, liquid, and gas.

b. Elements – Elements are substances that consist of only one type of atom. They are the fundamental
building blocks of matter and are defined by their unique atomic number.

c. Atoms – Atoms are the basic units of matter. They consist of a nucleus, which contains protons and
neutrons, and electrons orbiting the nucleus.

2. Application questions for the above terms:

a. Which of these groups have the largest number of members?

Atoms have the largest number of members since they make up all elements and, by extension, all
matter.

b. Which of these are the smallest in size? Atoms are the smallest in size among the listed terms.

3. Within an ATOM, differentiate Elementary Particles (e.g., protons, neutrons, and electrons

Elementary Particle Charge Size (approximate) Location
Proton +1 Very small Nucleus

Neutron 0 Very small Nucleus

Electron -1 Very small Electron

cloud(outside

nucleus)

Worksheet #1, page 2 BIO 1000 – Module 2

4. Application questions for the above table:

a. Which of these particles play a role in bonding?

Electrons play a significant role in chemical bonding. They are involved in forming chemical bonds by
being shared or transferred between atoms.

b. What is the job of the 3rd particle? When do we see that have an impact on an atom? The third
particle is the neutron, which is electrically neutral. Neutrons contribute to the stability of the atomic
nucleus and help prevent protons in the nucleus from repelling each other due to their positive
charges. Neutrons do not have a direct impact on the chemical properties of an atom but are crucial
for the atom’s overall stability.

5. Comparing atomic bonds: ionic, covalent, and hydrogen-bonding (see OpenStax, Concepts of Biology, Figure
2.5, and extra practice sheet for electron dot diagrams)

a. BASIC RULE for CHEMICAL BONDING:

 The goal of any bond is to be more STABLE (i.e. use less ENERGY).

 This is described by the OCTET RULE.

b. STEPS:

STEP 1: How many electrons are in the outer orbit? (use the Periodic Table)

STEP 2: Determine if the outer shell is full.

• Use the octet rule (except for Helium, on the top row).

• If the outer shell is FULL, it will neither accept any more electrons, nor will it give up any
electrons.

• COOL TRICK HERE: look at the Periodic Table.

o All of the atoms in the far-right column have FULL outer shells. (see column 18)

o They are called “Noble Gases” for this reason; they do NOT react (e.g., form bonds) under
normal circumstances.

STEP 3: If the outer shell is not full, decide whether the electrons will be “stolen” or “shared”.

• This depends how near the atoms are to one another on the Periodic Table. WHY?

• We call this the difference in “electronegativity.” If the atoms are further apart on the Periodic
Table, then the atom with an almost-full outer shell will be able “steal” another atom’s
electron(s) from its almost-empty outer shell.

• Opposite sides of the Periodic Table often means: LARGE or SMALL difference in electronegative.
WHY?

STEP 4: Draw the compound, showing the shared or stolen electrons (see OpenStax, Concepts of
Biology, Figure 2.5, and extra practice sheet for electron dot diagrams)

STEP 5: Determine the strength of the bond

• If the electrons are “stolen,” the bond is IONIC, and easier to break.

• If the electrons are “shared,” then the bond is COVALENT and much more difficult to break.

c. Application questions:

• Which has a stronger bond? SODIUM CHLORIDE (NaCl) or METHANE (CH4) Circle or highlight the
correct answer. . Sodium chloride (NaCl) has a stronger bond. It is an ionic compound, and
ionic bonds are generally stronger than covalent bonds. Methane (CH4) forms covalent bonds.

Worksheet #1, page 3 BIO 1000 – Module 2

• Explain why the above is true, according to step 5 Ionic bonds are stronger than covalent bonds
because they involve the transfer of electrons from one atom to another, leading to the
formation of ions with opposite charges that are strongly attracted to each other. In the case of
sodium chloride (NaCl), sodium donates an electron to chlorine, forming Na+ and Cl- ions,
which have a strong electrostatic attraction. Covalent bonds involve the sharing of electrons,
and the electrons are not fully transferred, resulting in a weaker bond.

d. ONE FINAL IDEA: After a molecule is formed, molecules are sometimes “pulled” toward each other.

• Hydrogen bonds are one example of this type of association between different molecules.

• Water is one of the most famous examples of Hydrogen Bonding, shown in OpenStax, Figure 2.7

Worksheet #1, page 4 BIO 1000 – Module 2

PRACTICE with drawing IONIC BONDING

1. Make an electron dot diagram of the atoms in the ionic compound.

2. Draw the BEFORE model on this paper. Next, show IONIC BONDING by moving the valence electron(s).

3. Draw the AFTER model. Use arrows to show the electrons being transferred and indicate the charge of
each atom.

PRACTICE with drawing COVALENT BONDING

1. Draw the electron dot diagrams of the atoms in each compound. RECOMMEND: use different colors for
each atom (or different “code”)

2. Then draw the line diagram to show each pair of shared electrons.

Worksheet #1, page 5 BIO 1000 – Module 2

Now that we have built the bonds, we can compare the bonds: ionic, covalent, and hydrogen-bonding.

Type of bond DEFINITION LOCATION of ELECTRONS STRENGTH

IONIC Involves the transfer of

electrons

Electrons are transferred Strong

COVALENT Involves sharing of

electrons

Electrons are shared Weaker than ionic

HYDROGEN-

BONDING

A type of covalent bond

where a hydrogen atom

is attracted oxygen or

nitrogen

Between hydrogen and

highly electronegative atom

like oxygen or nitrogen

Weakest

Describe the properties of water that are critical to maintaining life

1. Water is a POLAR molecule due to its bond type. What does this mean? Draw it below. (OpenStax, Fig. 2.7)

Water being polar means that it has an uneven distribution of charge. The oxygen atom in
water is more electronegative than the hydrogen atoms, so it attracts the electrons in the
covalent bonds more strongly. This results in a partial negative charge on the oxygen atom and
partial positive charges on the hydrogen atoms. This polarity gives water unique properties.

2. Because of its polarity, water has unique properties that support life on Earth. Name these four (4)
properties of water:

a. Cohesion: Water molecules stick together due to hydrogen bonding, allowing for surface tension
and capillary action.

b. Adhesion: Water can adhere to other substances, facilitating transport in plant tissues.

c. High specific heat: Water can absorb and store a large amount of heat, helping to regulate

temperature.

d. Universal solvent: Water can dissolve a wide range of substances, making it essential for

biological processes.

Describe the ways in which carbon is critical to life: Carbon is essential to life because of its ability to form diverse
and complex molecules. Life on Earth is based on organic compounds, which are primarily composed of
carbon atoms.

Life on Earth is also based on CARBON; often we call this “organic.”

A carbon atom can bond with 4 other atoms.

1. Draw the simplest carbon molecule: Methane (CH4) (OpenStax, Fig. 2.13)
CH4 consists of a carbon atom bonded to four hydrogen atoms.

2. Carbon can also make long-chain fatty acids; draw here. (OpenStax, Fig. 2.14)

Long-chain fatty acids are molecules with a carbon backbone and multiple hydrogen atoms attached. They are an

Worksheet #1, page 6 BIO 1000 – Module 2

essential component of lipids.

Contrast the four major types of biological macromolecules and their functions

1. CARBOHYDRATES are made of what three (3) things?

Carbohydrates are made of carbon, hydrogen, and oxygen


2. Always with a ratio of atoms at : : (such as glucose, C6H12O6)

The ratio of carbon, hydrogen, and oxygen atoms in carbohydrates is typically 1:2:1, as seen in glucose
(C6H12O6).

Worksheet #1, page 7 BIO 1000 – Module 2

3. LIPIDS include the following things:

Lipids include fats, oils, phospholipids, and steroids.


4. PROTEINS are made of individual parts called amino acids and have diverse functions.

5. NUCLEIC ACIDS include DNA and RNA. These are our genetic material (both genome and
message).