Transcript Chapter 2: Introduction to Chemistry

Chapter 2: Introduction to
Chemistry
A review
The basics:
• Chemistry is the science of the structure and
interactions of matter.
• Matter is anything that occupies space and has
mass.
• Mass is the amount of matter in an object.
• There are112 recognized chemical elements, each
designated by a chemical symbol.
• Elements are made up of atoms, the smallest units
of matter.
• Atoms are composed of protons (+), neutrons (0)
and electrons (-).
The main elements in the human
body:
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Oxygen (O) 65%
Carbon (C) 18.5%
Hydrogen (H) 9.5%
Nitrogen (N) 3.2%
Calcium (Ca) 1.5%
Phosphorus (P) 1.0 %
Other elements include: K, S, Na, Cl, Mg and Fe
Atomic number vs. Mass number
• The atomic number is
the number of protons
in an atom.
• A Cl atom has 17
protons, it has an
atomic number of 17.
• The mass number is
the number of protons
plus the number of
neutrons.
• Ex. Na has 11 p and
12 n, it has a mass
number of 23.
Chemical Bonds
• Ionic bonds – Positively charged ions and
negatively charged ions are attracted to each
other. Ex. Na and Cl ions.
• Covalent bonds – When neither of the
combining atoms loses are gains electrons,
but share them. Ex. H 0
• Hydrogen bonds – Polar covalent bonds
between H atoms and other atoms. But, are
considered weak. Join nitrogen bases
together in DNA.
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Chemistry and the Human Body
• Synthesis reactions: The
production of new and
larger molecules.
• Anabolism is the
collective term that
refers to the combining
of simple molecules
(amino acids) to form
larger molecules
(proteins)
2 Types of Chemical
Compounds
Inorganic
&
Organic
Inorganic Compounds
• Lack Carbon
• Are held together by ionic or covalent
bonds.
• Examples include water, salts and acids.
• The exceptions are 2-carbon containing
compounds CO and HCO 2
3
Organic Compounds
• Always contain carbon and usually
hydrogen.
• Always have covalent bonds.
• Examples include lipids, proteins, nucleic
acids, carbohydrates and ATP ( all
macromolecules )
Water
Water makes up 55 to 60
percent of lean adults and
is an excellent solvent.
Participates in chemical
reactions. Ex. Hydrolysis,
the process of breaking
down large nutrient
molecules into smaller
molecules. (digestion)
Water requires large
amounts of heat to change
from liquid to gas. This
makes water an excellent
cooling mechanism,
evaporation.
Water serves as a lubricant. It is a
major part of saliva and mucus.
Lubrication allows organs of the
thoracic and abdominal cavities
to slide over one another.
Lubrication is also needed at the
joints where bones, tendons and
ligaments rub against one
another.
Water absorbs and releases
heat slowly, this helps to
maintain homeostasis.
Acids, Bases and Salts
• Acids, bases and salts dissociate into ions in
water.
• Acids ionize into H ions (H+)
• Bases ionize into hydroxide ions (OH-)
• Salts ionize into either H+ or OH- ions
The pH Scale
• Acids range from 0–6
on the pH scale.
• Bases (alkaline) range
from 8-14.
• 7 on the pH scale is
considered neutral.
The body is sensative to even the
slightest changes in pH.
Anything outside of the normal
limits greatly disrupts the body’s
function.
Buffer systems are chemical
compounds that convert strong
acids and bases into weak acids
and bases.