Chapter 2 Outline
Mrs. Verrastro
The branch of science that deals with the composition of substances and
The changes that occur in that composition
Biochemistry:The chemistry of living organisms. Important for understanding
I. Structure of Matter:
A. Matter:
Anything that has weight and takes up space
Matter exists in three forms
1. Solid
2. Liquid
3. Gas
B. Elements: All things are composed of elements, which are the most
Basic chemical substances. There are 110 recognized
Elements. 92 are naturally occuring on Earth.
C. Atoms:
Living organisms require about 20 elements. By weight
95% of the human body is composed of just 4 of these
1. Oxygen (O)
2. Carbon (C)
3. Hydrogen(H)
4. Nitrogen (N)
All chemical elements are composed of tiny particles called
atoms. An atom is the smallest complete unit of an
1. Nucleus : The central portion of an atom. It contains particles called
protons and neutrons. They have about equal weights, and
are relatively large. Protons are positively charged.
Neutrons carry no electrical charge and are therefore
2. Electrons: Outside the nucleus there are other charged particles –
electrons-that are in constant motion orbiting the nucleus.
Electrons are very small and have almost no weight. They
also carry a negative charge.
3. Atomic Number: The number of protons in an atom. The number of
protons equals the number of electrons. The atomic
number also tells you how many number of electrons are in
an atom.
4. Atomic Weight: The weight of an atom is determined from the weight
of the protons and neutrons inside the nucleus.
5. Isotopes: Atoms that have the same atomic number but different
atomic weights. (Ex. Carbon-6 and carbon-14)
II. Molecules and Compounds:
When two or more atoms bind together they form a molecule. If the
atoms are the same type, they form a molecule of that element (O2 = a molecule of
If atoms of different types combine, they form a molecule of a compound.
A molecule is described by a molecular formula. It includes the letter symbol for the
elements and the numbers of atoms of each present.
Ex. H2O=water CO2=Carbon dioxide CO=Carbon monoxide
III. Chemical Activity-interactions of atoms:
How atoms interact is determined by how many electrons they contain.
A. Chemical Bonding:
1. Atoms joining: Atoms can combine with other atoms by gaining,
losing, or sharing electrons. An atom’s electrons are arranged around the
nucleus in 1 or more shells (Like the rings of Saturn). Each shell has a
certain capacity.
1st Shell- Can hold only 2 electrons
2nd Shell- Can hold 8 electrons
3rd Shell-holds more, and fourth still more.
The first shell fills first, then the remaining electrons begin to fill the
second shell. If it gets filled, the remaining electrons start to fill the third
shell, etc. ( draw pictures here)
2.Stable/Inert Atoms: If the outer shell is completely filled, such as with
helium, the atom is stable. It is chemically inactive=inert. It will not react
with other atoms. If the outer shell if not filled, the atom is unstable and
wants to become stable. It can easily gain, lose, or share electrons to
become stable. That’s how atoms interact.
3. Ionic Bonding: Atoms gain or lose electrons to become stable. Once
the electrons move, the atoms are no longer electrically neutral. An atom
that gains an electron now has an extra negative charge, an antom that
loses an electron has one less negative charge, making it positive.
Ions- Atoms that have an electrical charge from gaining or losing
Anion- a negatively charged ion
Cation-a positively charged ion
B. Covalent Bonding:
Atoms can also bond by sharing electrons. Hydrogen has only 1
electron in its outer shell. It needs another to be stable. So two hydrogen
atoms can share their electrons. (co-as in cooperating, or together)
(Draw picture here)
C. Hydrogen Bonds:
A hydrogen bond is a weak bond formed between hydrogen atoms
and another atom. Examples include liquid water and DNA chains. These
bonds are easily broken and put back together.
IV. The Organic Compounds
Organic compounds contain carbon, hydrogen, and usually oxygen
as well. Covalent bonds are most common.
A. Carbohydrates
Carbohydrates are sugars and starches. They are important energy
sources for metabolic operations. They Contain Carbon,
Hydrogen, Oxygen -1:2:1 ratio.
A simple sugar, or monosaccharide, has from three to seven carbon
atoms. Glucose is the most important monosaccharide.
Disaccharides and polysaccharides form by dehydration synthesis.
They can be broken apart through hydrolysis.
Glycogen is the most important polysaccharide in our bodies; it is a storage form
of glucose.
B. Lipids
Lipids are fats, oils, and waxes. Contain Carbon, Hydrogen, and Oxygen
But with a lot less oxygen than carbohydrates
Fatty acids are an example of lipids and are important energy sources.
Fatty acids can be linked to a glycerol molecule by dehydration synthesis to form
diglycerides and triglycerides. Triglycerides are an important storage form for
Prostaglandins and some steroids function as hormones.
Cholesterol is a precursor of steroid hormones, and is an important component of cell
Cholesterol, phospholipids, and glycolipids are the structural lipids of the body.
C. Proteins
Proteins have two functional groups- Amine group (- NH2) and a Carboxylic
group (- COOH) with an R group (radical-which determines what amino acid to
Structural proteins in the human body contain twenty different amino acids in
significant quantities,but there are over 100,000 different proteins.
Contains Hydrogen, Oxygen, Carbon, Nitrogen, sometimes sulfur
Proteins are important as enzymes, structural components, hormones, regulators
of metabolic activity, and buffers.They also function in movement,
transportation of dissolved materials, and defense against disease and physical
Enzymes are proteins that lower the activation energy requirements for chemical
Enzyme names usually end with "-ase." Hydrolases, such as carbohydrases,are
important enzymes responsible for breaking down compounds.
D. Nucleic Acids
Nucleic acids store and process genetic information concerning the structure of
proteins. There are two types of nucleic acids, ribonucleic acid (RNA) and
deoxyribonucleic acid (DNA).
Nucleic acids are chains of nucleotides. Each nucleotide contains a phosphate
group, a sugar, and a nitrogen base.
In RNA, the sugar is ribose, and the nitrogen base may be adenine, guanine, cytosine,
or uracil.
In DNA, the sugar is deoxyribose, and the nitrogen bases are the same except for the
substitution of thymine for uracil.
Mrs. Verrastro
1. _______ Fatty acids
a. Carbohydrate
2. _______Polysaccharide
b. Lipid
3. _______ C,H,O in a 1:2:1 ratio
c. Protein
d. Nucleic Acid
9.________ NH2 and COOH
10.________ DNA and RNA
11.________C,H, and a small amount of O
12.________Radical Group
13.________ Structural component of muscle
14.________ Insulates the body
15.________Stores and process information
16.________Primary energy sources for our bodies