Unit 2 BASIC CHEMISTRY NOTES

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.

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

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)

Levels of organization Atom Molecule Cell Tissue Organ Organ System Organism

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

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

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

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

medical imaging

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

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

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

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

common elements in body See Table 2.1 in Textbook for Role in Body Major (96.1%) O - 65% C - 18.5% 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

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.

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

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

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.

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

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