1. Unit 2
BASIC CHEMISTRY
NOTES

2. Chemical reactions underlie all body processes - movement, digestion, pumping of your heart, and even your thoughts. Knowing basic chemistry will help you understand body functions (physiology) and the role of food and medicine in the body.

3. MATTER v. ENERGY MATTER has mass (weight) and takes up space.
*Can be changed physically (chewing food with teeth) or chemically (digestion of food in stomach)
ENERGY is massless and does not take up space; it is the ability to do work; cannot be created or destroyed, but can be converted.
* Kinetic energy - when energy is actually doing work
* Potential energy - when energy is inactive or stored

4. forms of energy
Chemical - stored in bonds of chemicals; all body activities are powered by the chemical energy harvested from food
Electrical - results from movement of charged particles (ions); nervous system uses electrical energy to send signals
Mechanical - directly involved in moving matter; muscle movement
Radiant - travels in waves; x-rays, IR, light, radio, UV
Thermal - heat energy; all energy conversions in the body release heat (important in speed of chemical reactions)

5. Levels of organization
Atom
Molecule
Cell
Tissue
Organ
Organ System
Organism

6. periodic table of elements
Organized according to atomic structure and chemical characteristics

7. Remember: Like charges repel, opposites attract.
subatomic particles
Protons - in nucleus; + charge; mass is 1amu
Neutrons - in nucleus, no charge (neutral); mass is 1 amu
Electrons - tiny particles that orbit around nucleus; negative charge; 1/1800 amu

8. atomic number - number of protons
atomic mass number - sum of protons and neutrons
isotopes - element with same number of protons and electrons but vary in number of neutrons; same chemical properties
atomic weight - mass number of most abundant isotope

9. Radioisotopes - heavier isotopes that are unstable and tend to decompose to become more stable
Radioactivity - spontaneous atomic decay; involves ejection of particles (alpha or beta) or electromagnetic energy (gamma rays) from the atom’s nucleus; damaging to living cells

10. medical imaging

11. CT (computed tomography) - x-ray tube rotates around body, different tissues absorb the radiation in varying amounts (contrast medium can also be used)

12. PET (positron emission tomography) - Pt given injection of radioisotopes tagged to biological molecules (like glucose)

13. MRI (magnetic resonance imaging) - uses a magnetic field 60,000 times stronger than the earth’s; causes hydrogen molecules to spin; energy is released and translated to a visual image; very useful for view of soft tissues

14. Sonography (ultrasound imaging) - high frequency sound waves are reflected and scattered by body tissues, producing echoes; computer constructs a visual image; inexpensive and safe, but not good for looking at air-filled structures or those protected by bone

15. common elements in body
See Table 2.1 in Textbook for Role in Body
Major (96.1%)
O - 65%
C %
H - 9.5%
N - 3.2%
Lesser (3.9%)
Ca - 1.5%
P - 1.0%
K - 0.4%
S - 0.3%
Na - 0.2%
Cl - 0.2%
Mg - 0.1%
I - 0.1%
Fe - 0.1%
Trace (less than 0.01%)
Cr, Co, Cu, F, Mn, Mo, Se, Si, Sn, V, Zn

16. chemical bonds and rxns
Valence electrons - electrons in the outer shell of an atom; determines reactivity with other elements
Inert (or stable) elements, such as He, have a full outer shell
Chemically active elements, such as H, C, O, and Na, will tend to gain, lose, or share electrons to reach a stable state.

17. ionic bond
electrons are completely transferred resulting in negatively (anions) and positively (cations) charged ions; the opposite charges attract and stay close together - salts

18. covalent bond
electrons are shared so that each atom fills its valence shell at least part of the time

19. Carbon - the building block of life
Carbon is able to bond with up to four other elements or form double and triple bonds with other carbon atoms. Because of the unique bonding properties, there are millions of different organic chemicals. Each one has unique properties (functions). Most matter in your body that is not water is made of organic compounds.

20. hydrogen bonds
extremely weak bonds formed when H atom bound by a polar atom is attracted to another polar atom, and the H atom forms a bridge between them; common between water molecules

21. Decomposition Reactions Exchange (Single Replacement) Reactions
types of reactions
Synthesis Reactions
A + B --> AB
anabolic; important for growth and repair
Decomposition Reactions
AB --> A + B
catabolic; digestion of food (proteins, sugars)
Exchange (Single Replacement) Reactions
AB + C --> AC + B and AB + CD ---> AD + CB
Ex.: phosphate transferred from ATP to glucose in cells