AP Biology Unit 1 Background Documents

terms 1 - 21: doc 1

atom

one particle of a chemical element / smallest unit of an element

element

a substance that cannot be broken down into a simpler substance

proton

positively charged particle in the nucleus of an atom; same mass as neutron

neutron

chargeless particle in the nucleus of an atom

electron

negatively charged particle outside the atomic nucleus

compound

two or more different types of atoms form this substance

molecule

a particle consisting of one or more of the same or different atoms held together by chemical bonds. this is the smallest unit of a compound that displays the chemical properties of that compound

bonding

interaction between two atoms

ionic bonding

bond where atom loses an electron to another. this happens between elements at complementary extremes of the periodic table

covalent bonding

bond where electrons are shared between atoms

valence electrons

electrons in the outermost shell of an atom

polarity

ability of a molecule to form charged “poles” that interact with other charges

hydrophobic

water-hating, nonpolar, insoluble in water, usually greasy or fatty

hydrophilic

water-loving, polar, soluble in water, or forms hydrogen bonds with water

amphiphilic

a molecule possessing both hydrophobic and hydrophilic properties within itself; ex, soaps and many proteins

transparency (water)

light passes through; light can pass thru cells to reach the chloroplast for energy, water dwellers can see to move

cohesion/adhesion/surface tension (water)

water sticks to itself/water sticks to stuff/hard to break surface'; columns of water can be “sucked upward,” light animals can walk on water

solvent properties (water)

many substances dissolve in water making it ideal for biochemistry; water’s polarity allows it to transport these molecules effectively; ex: sugars and nutrients are easily dissolved and carried in living things

heat capacity (water)

large amounts of energy absorbed before temp goes up; stable temp allows water to be a good habitat and a vehicle for energy transfer; ex: lakes will hold temp for months, preserving life inside

boiling & freezing (water)

high boiling point.

low freezing point.

ice floats, less dense.

ice more rigid.

water rarely boils in nature, surface ice insulates and stabilizes temp

cooling/evaporation (water)

heat energy release during evaporation cools water and nearby molecules; water is an effective coolant as it evaporates, maintains homeostasis; ex: sweat maintains body temp by evaporating from skin

intramolecular bonds

happen within molecules; they are ionic (weak) or covalent (stronger)—IN AQUEOUS ENVIRONMENTS

intermolecular bonds

happen between molecules. they are weak and have to do with charge or structure/size