chapter 2: the chemistry of life

element

simplest form of matter with unique properties

atomic number

number of protons in the nucleus

minerals

inorganic elements extracted from soil by plants

electrolytes

mineral salts needed for nerve/muscle function

ion

charged particle with unequal number of protons/electrons

ionization

transfer of electrons to achieve a stable valance shell

anion

gains electrons (negative charge)

cation

loses electrons (positive charge)

electrostatic attraction

ions of opposite charge attract each other

free radicals

short-lived particles with unusual electron counts

antioxidants

chemicals that neutralize free radicals

isotopes

varieties of an element differing neutron number

radioisotopes

unstable isotopes that decay and emit radiation

radioactivity

decaying to stable isotopes and releasing radiation

physical half life

time for 50% of radioisotope to decay

biological half life

time for 50% to disappear from the body

radiation does units

sievert (Sv)

alpha particle

2 protons + 2 neutrons; can not penetrate body

beta particle

free electron; penetrates a few mm

gamma particle

penetrating; crazy dangerous rays

Molecule

chemical particle composed of two or more atoms united by a chemical bond

Compound

molecule composed of two or more different elements

Molecular formula

identifies constituent elements and how many atoms of each are present

Structural formula

identifies location of each atom

Isomers

molecules with identical molecular formulae but different arrangement of their atoms

Chemical bonds

Forces that hold atoms together within a molecule or attract one molecule to another

Ionic bonds

Attractions between anions and cations; Electrons donated from one atom to another

Single covalent bond

one pair of electrons are shared

Double covalent bonds

two pairs of electrons are shared; each C=O bond

Nonpolar

Electrons shared equally

polar

Electrons shared unequally

Hydrogen bond

a weak attraction between a slightly positive hydrogen atom in one molecule and a slightly negative oxygen or nitrogen atom in another

Van der Waals forces

weak, brief attractions between neutral atoms

Mixtures

substances physically blended but not chemically combined

solvency

the ability to dissolve other chemicals

cohesion

the tendency of molecules of the same substance to cling to each other

adhesion

the tendency of one substance to cling to something else

chemical reactivity

the ability to participate in chemical reactions

thermal stability

helps to stabilize the internal temperature of the body

hydrophillic

substances that dissolve in water

hydrophobic

substances that do not dissolve in water

calorie (cal)

the amount of heat that raises the temp. of 1g of water 1C

solutions properties

particles under 1nm; do not scatter light; pass through most membranes; will not separate

colloids

mixtures of proteins and water

colloid properties

particles between 1-100nm; scatter light; particles too large to pass through the membrane; will not separate

suspension properties

particles exceed 100nm; too large to pass through membranes; cloudy or opaque; will separate

emulsion

suspension of one liquid in another

Acid

proton donor (releases H+)

base

proton acceptor (accepts H+; some release OH-)

pH

measure derived from the molarity of H+

buffer

chemical solutions that resist changes in pH

normal blood pH

7.35-7.45

acidosis

below 7.35

alkaosis

above 7.45

molarity

number of moles of solute/liter of solution

energy

capacity to do work

potential energy

energy stored in an object, not currently doing work

chemical energy

potential energy in molecular bonds

free energy

potential energy available to do work in a system

kinetic energy

energy of motion, doing work

heat

kinetic energy of molecular motion

electromagnetic energy

the kinetic energy of moving “packets” of radiation (photons)

chemical reaction

process in which a covalent or ionic bond is formed or broken

chemical equation

symbolizes the course of a chemical reaction

decomposition reaction

large molecule breaks down into smaller ones

synthesis reaction

process of two or more small molecules combine to form a larger one

exchange reaction

two molecules exchange atoms or group of atoms

reversible reaction

reaction that can go either direction

law of mass action

direction of reaction determined by relative abundance of substances

equilibrium

ratio of products to reactants is stable

concentration

more concentrated, more collisions, faster rate

temperature

higher temperature, greater collision force, faster rate

enzyme

speeds up reaction without permanent change to itself

particle size

smaller move faster

metabolism

all chemical reactions of the body

catabolism

energy releasing (exergonic) decomposition reactions

anabolism

energy storing (endergonic) synthesis reaction

oxidation

chemical reaction when a molecule gives up electrons; releases energy

electron acceptor molecule

oxidizing agent

reduction

chemical reaction when a molecule gains electrons; gains energy

molecule that donates electrons

reducing agent

macromolecules

large organic molecules with high molecular weights

polymers

macromolecules made of a repetitive series of monomers

monomers

identical or similar subunits

polymerization

joining monomers to form a polymer

dehydration synthesis

how living cells form polymers

hydrolysis

how living cells break polymers

carbohydrates

hydrophilic organic molecule

Carbohydrate formula

(CH₂O)_n, n= carbon atoms

disachharide

sugar molecule made of two monosaccharides

sucrose

table sugar; glucose + fructose

lactose

sugar in milk; glucose + galactose

maltose

grain products; glucose + glucose

oligosaccharides

short chain of 3 or more monosaccharides (up to 10)

polysaccharides

long chains of monosacchariedes (at least 50)

glycogen

energy storage in cells

starch

energy storage in plants (digestible)

cellulose

structural molecule in plants (indigestible)

glycolipids are found

external surface of cell membrane

glycoprotiens are found

external surface of cell membrane; mucus