Chapter 2: The Chemical Level of Organization

matter

anything that takes up space and has mass

element

a pure substance that is distinguished from all other matter by the fact that it cannot be created or broken down by chemical means

atom

the smallest quantity of an element that retains unique properties of that element

proton

heavy subatomic particle having a positive charge and found in the atom’s nucleus

neutron

heavy subatomic particle having no electrical charge and found in the atom’s nucleus

electron

subatomic particle having a negative charge and nearly no mass; found orbiting the atom’s nucleus

atomic number

the number of protons in the nucleus of the atom

mass number

the sum of the number of protons and neutrons in the nucleus

periodic table of elements

arrangement of the elements in a table according to their atomic number; elements having similar properties because of their electron arrangements compose columns in the table, while elements having the same number of valence shells compose rows in the table

all elements in the body come from:

food you eat, air you breathe

compound

a substance composed of 2 or more elements joined by chemical bonds

isotope

a different form of an element distinguished by number of neutrons

radioactive isotope

unstable, heavy isotope that gives off subatomic particles, or electromagnetic energy, as it decays; also called radioisotopes

electron shell

area of space a given distance from an atom’s nucleus in which electrons are grouped

every element present in the human body contains how many electron shells?

between 1 and 5

how many electrons can each shell hold?

the first shell can hold 2, all others can hold 8

valence shell

an atoms outermost electron shell

if an atom is stable, this means that its valence shell:

is full, has 8 electrons

if an atom is reactive, what does that indicate about its valence shell?

it’s not full, has fewer than 8 electrons

octet rule

an atom will give up, gain, or share electrons with another atom so that it ends up with 8 electrons in its own valence shell

bond

a weak or strong electrical attraction that hold atoms in the same vicinity

molecule

a grouping of 2 or more atoms held together by chemical bonds

compound

a molecule made of atoms of 2 or more different elements

ionic bond

an ongoing, close association between ions of opposite charges

ion

an atom with an electrical charge

cation

a positively charged ion

anion

a negatively charged ion

covalent bond

atoms share electrons in a mutually stabilizing relationship

covalent bonds are ________ than ionic bonds

stronger

polar molecule

a molecule containing regions that have opposite electrical charges

hydrogen bonds

dipole-dipole bond in which a hydrogen atom covalently bonded to an electronegative atom is weakly attracted to a second electronegative atom

kinetic energy

the form of energy powering any type of matter in motion

potential energy

the energy of position, or the energy matter possesses because of its motion

where is potential energy stored in the human body?

the bonds between atoms and molecules

exergonic reactions

chemical reactions that release more energy than they absorb

endergonic reactions

chemical reactions that absorb more energy than they release

mechanical energy

stored in physical systems; directly powers the movement of matter

radiant energy

emitted and transmitted as waves of varying lengths rather than matter

electrical energy

supplied by electrolytes in cells and body fluids; contributes to the voltage charges that help transmit impulses in nerve and muscle cells

reactant

one or more substances that enter into the reaction

product

one or more substances produced by a chemical reaction

synthesis reaction

a chemical reaction resulting in the joining of components that were formerly separate

decomposition reaction

chemical reaction that breaks down something larger into its constituent parts

exchange reaction

type of chemical reaction in which bonds are both formed and broken, resulting in the transfer of components

what are some factors that influence the rate of chemical reactions?

properties of reactants, temperature, concentration, pressure, catalysts

enzyme

a catalyst composed of protein or RNA that works by lowering the level of energy required for a chemical reaction

concentration

the number of particles in a space

arrange the states of matter in order from most to least reactive

gas, liquid, solid

activation energy

the threshold level of energy needed to break the bonds in reactants

catalyst

a substance that increases the rate of a chemical reaction without undergoing any change itself

organic compound

a substance containing both carbon and hydrogen

inorganic compound

a substance not containing both carbon and hydrogen

which inorganic compounds are essential for human life?

water, salts, acids/bases

mixture

a combination of 2 more more substances, each of which maintains its own chemical identity

what are the 3 types of liquid mixtures?

solutions, colloids, suspensions

what are some functions that water performs in the body?

lubricates and cushions joints and organs, protects cells and organs from physical trauma, absorbs and dissipates heat to regulate body temperature

solution

homogeneous liquid mixture in which a solute is dissolved into molecules within a solvent

colloid

liquid mixture in which the solute particles consist of clumps of molecules large enough to scatter light

suspension

a liquid mixture in which a heavier substance is suspended temporarily in a liquid but settles out over time

sedimentation

the separation of particles from a suspension

dehydration synthesis

aka condensation reaction; one reactant gives up a hydrogen atom and another gives up a hydroxyl group in the synthesis of a new product, releasing water as a byproduct

hydrolysis

a molecule of water disrupts a compound, breaking its bonds; the water molecules split into hydrogen and oxygen atoms. one portion of the broken compound bonds with the hydrogen atom, the other portion bonds with the hydroxyl group

salts

substances formed through ionic bonds that, when dissolved in water, dissociate into ions other than hydrogen or hydroxyl groups

acids

substances that release hydrogen ions in a solution

strong acids

compounds that ionize completely, or release all their hydrogen ions in a solution

weak acids

compounds that do not ionize completely; some of their hydrogen ions remain bonded within a compound in solution

bases

substances that reduce the acidity of a solution by releasing hydroxyl ions in solution, or accepting hydrogen ions already present in a solution

strong bases

release most or all of their hydroxyl ions

weak bases

release only some hydroxyl ions or absorb only a few hydrogen ions

buffer

a solution of a weak acid and its conjugate base; neutralizes strong acids in body fluids

what is the normal pH range of human blood?

7.35 to 7.45

pH

negative logarithm of the hydrogen ion (H⁺) concentration of a solution

the pH scale ranges from:

0 to 14

a pH below 7 is:

acidic

a pH above 7 is:

basic

a pH of 7 is:

neutral

how many electrons does carbon have in its valence shell?

4

how do carbon atoms typically fill their valence shells?

covalent bonds

functional group

a group of atoms linked by strong covalent bonds and tending to function in chemical reactions as a single unit

macromolecule

any large molecule

carbohydrate

aka saccharides; a molecule composed of carbon, hydrogen, and oxygen

polysaccharides

compound consisting of more than two carbohydrate monomers bonded by dehydration synthesis via glycosidic bonds

monosaccharides

monomers of carbohydrate; also known as a simple sugars

disaccharides

pairs of carbohydrate monomers bonded by dehydration synthesis via a glycosidic bond

name three important polysaccharides for human function

starch, glycogen, cellulose

name five important monosaccharides for human function

glucose, fructose, glacatose, deoxyribose, ribose

name three important disaccharides for human function

sucrose, maltose, lactose

which cells can only use glucose as fuel for essential functions?

neurons, spinal cord, peripheral nervous system, red blood cells

lipid

class of nonpolar organic compounds built from hydrocarbons and distinguished by the fact that they are not soluble in water

triglyceride

aka fat; lipid compound composed of a glycerol molecule bonded with three fatty acid chains

glycolipids

sugar-fat compounds found in cell membranes

lipoproteins

compounds where hydrophobic triglycerides are packahed in protein envelopes for transport in body fluids

saturated fatty acids

straight, rigid fatty acid chains that have no double carbon bond anywhere along their length and therefore contain the max number of hydrogen atoms; solid or semi-solid at room temperature

unsaturated (monosaturated) fatty acids

kinked at their singular double carbon bond, therefore unable to pack together tightly; liquid at room temperature

trans fats

created when unsaturated fats are chemically treated to produce partially hydrogenated fats

polysaturated fatty acids

contain two or more double carbon bonds; liquid at room temperature

phospholipid

a bond between the glycerol component of a lipid and a phosphorous molecule

steroid (sterol)

lipid compound composed of four hydrocarbon rings bonded to a variety of other atoms and molecules

prostaglandin

lipid compound derived from unsaturated fatty acid chains and important in regulating several body processes

protein

an organic molecule composed of amino acids linked by peptide bonds