Kingwood College Respiratory Care department
RSPT 1325 Respiratory Care Sciences Unit 2: Chemistry for Respiratory Care
Lecture notes by Elizabeth Kelley Buzbee AAS, RRT-NPS, RCP
READING:
Egan’s Fundamentals of RC: Chapter 11
1.
Define some basic terms:
Atom: the smallest subdivision of a substance that still holds the properties* of
that substance. Each atom contains a center nucleus with protons and neutrons.
The proton has a + charge while the neutron has no charge.
*Physical properties are measurable properties that we can sense or measure:
smell, taste, color, as well as boiling and freezing points.
Chemical properties will describe the element’ ability to interact with other
atoms, or elements. [reference: Marieb pp. 26]
Circling the nucleus are the electrons with - charges which have a weight that is
1/1000 of the proton or of the neutron. The number of electrons is always equal
to the number of protons in the atom.
element
Number of
Number of
proton
Electrons?
barium
56
copper
29
iron
26
Trick: to remember this: proton + attract electrons - because
opposites attract.
Element: a general term for the 106 different types of atoms [only 92 are
natural, the rest created in particle accelerators.]
The difference between one element and another is the actual makeup of the
atoms of these substances. The number of protons and neutrons in the center of
the atom and the number of orbiting electrons will change the element
drastically.
The atomic number is equal to the number of protons in the nucleus of an
atom. Below you can see the small difference between Helium and Carbon and
the huge difference between these common elements and plutonium.
The atomic mass is equal to both the proton and neutrons in the nucleus.
Go here to see the periodical table: http://en.wikipedia.org/wiki/Periodic_table
The element, oxygen, has an atomic number of 8, which means that the atom has
8 protons in its nucleus.
It has an atomic mass of 16 because there are an equal mass of protons and
neutrons in the 0xygen atom’s nucleus.
element
Oxygen [O]
Carbon [C]
Calcium [Ca]
Chloride [Cl]
Sodium [Na]
Atomic
number
8
6
20
17
11
how many protons in this
atom?
Number of
Electrons?
Mass and weight: the mass of an element does not change, but the actual
weight varies based on the position of the element in the atmosphere. An atom of
oxygen weighs more at sea level than it does on the space lab because of gravity.
Its mass is always the same.
Gram molecular weight [GMW]
we tend to speak of the weight of various elements in terms of gram molecular
weight [GMW] mass in grams = to its molecular weight
The function of Avogadro’s number [6.02 x 10 23]
There are 6.02 x 10 23 particles contained in each 1 gram atomic weight. This will
convert the elements from extremely tiny to something large enough to study [pp
Kacmarek pp. 19]
One mole of any substance contains exactly 6.02 x 10 23 particles of that
substance. [Marieb pp. 30]
Isotopes: Most elements have various forms in which they have same protons
but the number of neutrons varies. Oxygen has three isotopes: One with 8,
another with 9, and a third with 10 neutrons. 99% of all 02 atoms are in the first
isotope.
Isotopes of an element have the same atomic numbers [protons only], but they
may have different atomic masses [protons + neutrons] because the number of
neutrons varies.
Many heavy isotopes are unstable and will degrade into more stable forms. This
degradation is called radioactivity. It seems that the ‘glue’ that holds atoms
together is harder to maintain in larger elements.
Isotopes that degrade like this are called radioisotopes and the time required for
a radioisotope to degrade ½ of its activity is called its half-life. (Marieb pp. 28)
The atomic weight of an element is based on the average of the relative weights
of all the isotopes in the element.
Electron shells
The electrons [-] orbit the nucleus of the atom in shells numbered 1-7. Electron
shell # 1 is closest to the center with electron shell 7 farthest away. See pg. 167.
The inner shells must fill before the electrons move to the next shell.
Each shell can hold only a limited number of electrons,
 the first shell can holds only 2 electrons,
 the second & 3rd hold 8,
 and the 4th & 5th shells hold 18
 while the 6th & 7th hold 32.
But all they need to be stable is 8 in the outer shell
element
Atomic How many electrons are in
Would this
number
the outer layer?
be reactive?
Oxygen [O]
8
Carbon [C]
6
Calcium [Ca]
20
Chloride [Cl]
17
Sodium [Na]
11
The electrons of the outer layers are more likely to interact with other atoms
because they are not held as tightly to the nucleus as the inner shells electrons are
held.
An outer shell that contains less than 8 electrons will more easily gain, loss or
share electrons with another atom.
Valence: describes the reactivity of a given atom. An atom with a valence of -1 is
an atom that will accept one more electron. An atom with a valence of +2 is one
that will lose two electrons. Valence is based on the outer shell of the atom which
is the one that is responsible for reactivity by losing or gaining electrons.
This is how various elements can combine into molecules.
element
Valence of the outer
Means this element can:
shell
Oxygen
-2
Accept 2 electrons
Hydrogen
+/-4
zinc
+1 or +2
phosphorus
-4
magnesium
+2
chloride
-1
Noble gases are those elements that have complete outer shells so that they do
not interact with other elements. They have the max number or they have 8
electrons in their outer shell.
the trick to remembering valence: the outer shell that is -2 is the
one that is missing 2 electrons, so that it can accept 2.
The outer shell that has a valence of +2 is the one that has 2 extra
electrons to give away.
90% of the body is made up of only 4 elements: carbon, oxygen, hydrogen and
nitrogen.
element
Approx.
body
mass
oxygen
65%
Carbon
18%
hydrogen
9%
Nitrogen
3%
functions
Major component of both organic and inorganic
molecules, the gas [02] is necessary for energy
production ATP [aerobic metabolism]
Primary component of all organic molecules
Component of all organic molecules, as a ion H+ affects
the pH of the body. pH is the log of the H+
Genetic material
The other 10% of the body consists of a dozen or more trace elements.
Molecules and combinations
Few atoms exist in the free state for very long. They tend to combine, and
recombine into molecules.
A molecule is a combination of two or more atoms. It can be a molecule of two
like atoms such as 02 which are two oxygen atoms or it can be a combination of
two different elements.
Combinations of two or more different elements are called compounds. NaCl is
an example of a compound of Na [sodium] and chloride Cl. Compounds cannot
be separated into their basic building blocks without breaking bonds.
These elements are combined and recombined in various formulations to create
different substances: for instance: H20 is made up of 2 hydrogen and 1 oxygen
atom, while C02 is one carbon atom with 2 oxygen atoms.
It is important to remember that a compound can
have radically different chemical and physical
properties from the single elements making up these
molecules.
A cup of cream, dash of salt, an egg, 3 tablespoons of sugar
and ½ teaspoon of vanilla are mixed and cooked over the
stove to create pudding. The pudding is a compound of these various substances
and is no longer milk, egg, sugar nor is it vanilla. It is pudding.
The oxygen [O2] we breathe is a combination of 2 atoms of oxygen. We cannot
utilize an atmosphere made of triple 0xygen atoms [O3] because our cells cannot
use this ozone. A single oxygen atom [O] is the infamous 02 radical which causes
so much damage to the body.
As the cell uses up 02, oxygen radicals result. This is the basis for the
phenomenon: 02 toxicity; the buildup of 0xygen radicals damages the lung tissue
creating scar tissue. So…. different combinations of a single element, like oxygen,
will have drastically different properties.
Organic elements
Elements that combine into molecules and compounds that make
up all living [plants, animals, microbes] are carbon-based, so will
always have carbon atoms in their molecules. Note that both the
carbohydrate and the protein molecules contain a backbone of
carbon atoms. Carbon atoms can bond at 4 different sites
Protein molecule
Carbohydrate molecule
Excellent page for visualizing organic molecules
http://www.chemguide.co.uk/basicorg/conventions/draw.html
Physical Combinations
Elements that are combined chemically are called molecules, but 2 or more
compounds can be mixed in physical combinations without undergoing chemical
bonding. Substances in mixtures can be removed from the mixture by straining
or filtration
Solutions are homogenous mixtures of 2 or more compounds. These can be
gases, liquids or solids. The air we breathe is a solution of gases. The sea is a
solution of water, sand, microbes & salt.
Solutions are solutes that dissolve into solvents. In the body the single
largest and most important solvent is water. Solutions are usual clear because the
compounds are in atomic and molecular form. They do not settle out, nor bend
light.
Collides are mixtures of slightly larger compounds in solvents. While these
parts aren’t big enough to settle out, they can bend light and appear milky or
cloudy. A property of collides is that they can revert between solid
[gel] and liquid [sol] state. Jell-O is an example of a collide.
Sputum is a collide; as the water evaporates from it, sputum moves
from the sol to the gel state- it thickens.
Suspensions are heterogeneous mixtures of 2 or more compounds which are
large sometimes visible solutes. Blood is an example of a suspension, the
large compounds such as red and white cells are suspended in the fluid of the
blood plasma. These huge compounds make blood opaque and can settle out.
Types of chemical bonds
As stated earlier, compounds result because atoms with outer shells of less than 8
electrons gain, loss or share electrons with other atoms.
Ionic bonds: these chemical bonds result from the exchange of electrical
charges. These bonds result in the creation of ions which are charged particles
Remember that the electrons have – charges. When an atom accepts extra
electrons [anion] , this results in an increase in over all – charges for that atom.
Atoms that lose electrons [cation] results in overall + charges.
Because opposite charges attract, the two atoms are now have an
ionic bond.
An example of an ionic bond is NaCl.
The single Na atom has an outer shell with only 1 electron, so that it easily gives
this one up to become the cation, Na+
Chloride [Cl-] needs only one more electron to fill its outer shell, so it gains the
one lost by the Na+ and become the anion Cl-. The bond between these two is due
to the Na+ and Cl- ions attractions to one another.
Covalent bonds
These bonds are created by two atoms sharing electrons in their outer shells.
When two atoms share only one bond the relationships is represented by the
following symbol __ if the atoms share more than one electron their bond would
be represented by the symbol ==.
Covalent bonds can be polar or nonpolar based on the configuration of the actual
molecule.
Hydrogen bonds
Are too weak to hold entire compounds together, but these bonds do occur inside
some of the larger molecules. This bonding is due to attraction of negative and
positive charges.
Patterns of chemical reactions
Sythesis reaction: When atoms combine we have sythesis reaction.
Sythesis reactions form the constructive bonding or anabolic actions of the body.
Anabolic chemical reactions tend to use up energy.
4H + C
CH4
In the above example, 4 hydrogen atoms combined with a single carbon atom to
become the molecule methane
Decomposition reaction When a compound pulls apart into
separate elements we have a decomposition reaction. Catabolic reactions are used
break down protein into amino acids, carbohydrates into simple sugars. Breaking
bonds tends to release energy
AB
A+B
Exchange reactions: These are combinations of sythesis and
decomposition reactions. In an exchange reaction bonds are broken and
‘partners’ are changed with new bonds created.
AB + C
AC + B
Oxidation reduction reaction
These are also combinations of sythesis and decomposition reactions. In
oxidative portion of the reaction that loses an electron is called the donor and it
has been oxidized, while the other portion of the reaction that gains an electron is
called the acceptor and is considered reduced.
Cellular respiration is an example of oxidation-reduction reactions.
C6H1206 + 6O2
6C02 + 6H2O + ATP
Basically, glucose & oxygen converts into carbon dioxide, water and energy for
the cell. The cell uses the energy and the water and C02 are waste products
All the chemical reactions in the body, both catabolic and anabolic,
are called metabolism.
Factors that will effect chemical reactions in the body
usually result from atoms smashing into one other
1. temperature: most chemical reactions happen faster when the
elements are moving faster as they do when the temperature is up.
2. size: smaller particles [molecules or elements] will react more quickly
than larger ones will
3. concentration: the greater the concentration of an element the more
likely the molecules or the atoms with reaction with one another
4. Catalysts: A substance that quickens or starts a reaction without
changing itself is a catalyst. Because the catalysts doesn’t change a few
molecules of a given catalyst can be available for thousands of reactions
in rapid succession.
Because there is a limit to how hot the body can get, a huge number of
body’s reactions happen only due to the presence of a catalyst. Most of the
enzymes in the body are catalysts.
The role of water in the body’s chemistry
1. Water is considered the universal solvent and most organic
reactions cannot happen except in solution in water.
2. Water will disassociate some molecules because of its polarity.
3. Water will cool off reactions in the body
4. Water reacts with some substances by breaking them down. This is
called hydrolysis. “Water-breakdown”
Reversible chemical reactions
Some chemical reactions are reversible. This is designated by a double arrow
A famous example of an extremely unstable reaction is the C02 [carbon dioxide]
and H20 [water] reaction: the hydrolysis of C02
CO2 + H2O
H2C03
HCO3- +
H+
As C02 builds up in the system and comes into contact with water, the resulting
carbonic acid (H2C03) disassociates into more and more bicarb (HCO3-) and
H+.
As more and more bicarb and H+ accumulate, the action moves back toward the
creation of more C02 and water
This reaction is moved back and forth attempting to create equilibrium. The
amount of C02 in the body is one of the determinants of how much H+ is in the
body. H+ determines the pH of the body.
In the renal cell, in an effort to swing the reaction in one direction, to create more
H+ the hydrolysis of C02 can be speeded up by more than 3,000 x by the
addition of a catalyst, the enzyme, carbonic anhydrase.
pH of the body
pH is a measurement of acidity of a substance. The pH of the body is determined
by the number of free H+ present in the body. More H+ in the body, the more
acidic it is. The pH of pure water is 7.0.
When we add C02 to this water, we see that free H+ build up. This drops the pH
to a lower number. The more H+ in the body the lower the pH will be.
An acid is a number lower than water’s pH and a base is higher than water’s. The
range of pH is from zero to 14 with 7.0 in the absolute middle. The relationship
between 1 pH unit changes represents a 10fold change in H+ concentration. It is
logarithmic relationship. Remember the Henderson-Hasselbalch equation?
Blood pH
Because blood is mostly water, the normal pH of arterial blood is 7.35 to 7.45.
Because there is more C02 in the venous blood than in arterial blood, the pH of
venous blood is 7.34 to 7.37.
Urine pH
The normal pH of urine is very low [about 5] because one of the jobs of the renal
system is to capture free H+ and send them out of the body.
For most chemical reactions in the blood to happen as they should, the pH needs
to stay within very narrow parameters. Many substances cannot pass the cell
membrane if the pH is not with normal limits & many drugs will not work in an
acidic or alkaline pH.
Hydrolysis of C02 is the bases for the statement that “C02 makes acid.” As the
patient’s blood C02 rises, the reaction moves to the right and more H+ are
created.
On the other side of the coin, because C02 can be released at the lungs during
exhalation, we can get ride of excessive H+ by breathing faster and deeper.
Increasing the VE drops the C02 which drops the H+ level which raises the pH of
the blood. In fact, we breathe to get rid of C02, not to raise our 02 levels.
Remember the patient with hypoxic drive who has chronic hypercapnea? Because
his brain no longer notices the high C02, he is forced to breathe to keep his Pa02
between 55-65 mmHg.
Buffers
A substance that captures free H+ is called a buffer. HC03- can capture a free H+
to become H2Co3, which is a weak acid but this substance is too unstable to stay
carbonic acid.
Note that HCO3- can capture H+ because it has a place on its outer shell for an
ionic bond. Other buffers in the kidneys will capture H+ and force them out of
the body into the urine stream.
The blood’s pH is the result of the concentration of Carbonic acid and
bicarbonate. Carbonic acid and C02 have a linier relationship so that we can
convert PaC02 into carbonic acid by multiplying it by .03.
pH = 6.1 + log of
[
HC03(PaC02 x .03)]



As HC03- rises, the pH tends to rise
As PaC02 rises, the H2C03 rises, so the pH tends to drop
If both HCO3- and PaC02 rise, the pH may not change at all…this
is the basis for compensation of metabolic or respiratory problems
by throwing something else out of range.
States of matter
All substances exist in one of three states of matter: liquid, solid and gas.
The effect of temperature on states of matter
Most substances move between these three states with temperature changes.
Physical properties of a substance always include its boiling and its freezing
point.
The boiling point of a liquid is the temperature at which all of the substance
turns into a gas. It boils off into a gas.
Before a liquid boils off, individual molecules close to the surface may became
vaporous [gas] before the actual boiling point is reached. This is called
evaporation.
The freezing point of a substance is the temperature at which the substance
turns from a liquid to a solid.
Sublimation is the movement of a solid directly into a gas without going
through the liquid state.
Temperature
The kinetic energy and the intermolecular attraction of a substance determines
its state of matter. Generally the substance with the highest kinetic is more likely
to exist as a gas or a liquid. As the temperature rises, the kinetic energy of a
substance rises.
Absolute zero is the point at which a substance should have no kinetic energy—
theoretically.
The intermolecular attraction of molecules tends to hold them together in more
static states such as liquids or solids. Conditions such as polarity and weak
hydrogen bonds can hold like molecules together.
The units of temperature include: Fahrenheit [F] Celsius [C] & Kelvin [K]
These scales of temperature vary based on where zero is found.
Normal body temperature is considered 98.60 F, but is 370C.
 C =5/9 (F -32)
 F = [9/5 C] + 32.
Calculate these
Temperature in C
Temperature in F
98.6
40
32
Kelvin scale contains absolute zero, which is a point at which there is no longer
kinetic activity and the molecules are completely still.
K = C + 273
Temperature changes for various substances:
substance melting
Boiling point
0C
100 C
water
-218.8 C
-183 C
02
-57.6 C
-78.5 C
C02
-210 C
-192 C
Nitrogen
At sea level, water melts [goes from solid to liquid] at a temperature of zero
degrees C. At what temperature Fahrenheit, does water melt?
At what point in Fahrenheit dose 02 melt?