Class notes
BIOL 101 Chapter 2 Lecture Notes
- Course
- Biology 101
- Institution
- Delgado Community College
This is a comprehensive and detailed note on Chapter 2;the chemistry of life for Biol 101. An Essential Study Resource just for YOU!!
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Chapter 2: The Chemistry of LifeChapter 2 Learning Objectives:
• Identify the most abundant essential elements in living organisms.
• Describe the structure of atoms.
• Differentiate between atoms and molecules.
• Use the number of valence electrons in an atom to predict the number of bonds it
will form.
• Compare and contrast ionic, covalent, and hydrogen bonds.
• Explain how the structure of water affects its chemical properties.
• Explain how acids and bases affect pH.
• Differentiate between dehydration synthesis and hydrolysis.
• Compare and contrast the structures and functions of the four main classes of
organic molecules.
2.1 Atoms Make Up All Matter
A. Elements Are Fundamental Types of Matter
● A chemical element is a pure substance that cannot be broken down by chemical
means into other substances. Examples include oxygen (O), hydrogen (H), and
carbon (C).
● Matter is any material that takes up space, such as organisms, rocks, the oceans,
and gases in the atmosphere.
● Bulk elements are the elements that are required in the largest amounts because
they make up the majority of every living cell. The four most abundant bulk
elements in cells are:
o Carbon
o Hydrogen
o Oxygen
o Nitrogen
● Trace elements are elements that are required in smaller amounts.
● Elements are arranged in the periodic table in such a way that their chemical
properties repeat in vertical columns.
B. Atoms Are Particles of Elements
An atom is the smallest unit of matter that is unique to a specific element. Atoms are
composed of 3 subatomic particles.
List the particles, their charge, and location.
, Particle Charge Location in Atom
Proton Positive (+) In the nucleus (Much larger than the
electrons)
Neutron No charge In the nucleus (Much larger than the
electrons)
Electron Negative Outside the nucleus (Electrons move
around the electron cloud locations
where they are most likely are
orbitals)
Relative to protons and neutrons, electrons are very small. Most of the mass of an atom
is in the nucleus.
The charge is an electrical property that attracts or repels other subatomic particles.
Opposite charges attract, like charges repel.
-Positive and negative charges cancel each other: if there are the same number of
protons and electrons, the atom has no charge. (Will start with the assumption that
electron number+proton number)
Elements are pure substances consisting only of atoms with the same number of
protons in their nucleus.
● Define atomic number: number of protons in an atom: Examples: Carbon has
six protons. Oxygen always has 8 protons
2. Each element has a unique symbol, usually derived from Greek or Latin words.
The atomic number is shown above the symbol for each element.
C. Isotopes Have Different Numbers of Neutrons
● All atoms of an element have the same number of protons, but atoms can have
different numbers of neutrons and electrons.
What are isotopes? Atoms of the same element with different numbers of neurons
What is atomic mass? A number of protons and number of neurons
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