Biology Unit 2 Topic 1 Definitions and Vocab

matter

anything that takes up space and has mass

mass

the quantity of matter in an object

weight

the force of gravity on mass

atom

smallest component of an element that still retains its properties

element

substance that can't be further broken down without changing its properties

atomic nucleus

the center of the atom, contains protons and neutrons

atomic mass

the mass of an atom, protons + weighted average of neutrons in all isotopes existing in nature

proton

positively charged subatomic particle found in the nucleus, number determines the element of the atom

electron

a negatively charged subatomic particle found rapidly circling the nucleus in orbitals

neutron

neutrally charged subatomic particle found in the nucleus, responsible for isotopes

orbitals

regions around the nucleus where electrons are found

valence orbital

the outermost orbital from the nucleus, empty spots in this orbital determine the atom's ability to bond

isotopes

variants of an element with differing numbers of neutrons

compound

molecule with two or more elements in fixed proportions

chemical formula

shows type and proportions of atoms in a compound

noble/inert

an atom from an element that has a full valence orbital and thus doesn't bond

bonds

ways for atoms to exchange electrons to fill their valence orbital/become stable

covalent bond

a chemical bond where atoms share one or more pairs of electrons

molecule

the smallest amount of a substance that retains its properties

ionic bond

a chemical bond where one atom transfers an electron to another atom, creating one positive ion and one negative ion that attract each other

energy

the ability to do work, cannot be created or destroyed

thermal energy

a form of energy that must be added or removed from a substance to change its state of matter

chemical reaction

one or more substances change (form and break bonds) to produce one or more different substances

metabolism

chemical reactions that occur to provide energy for the body

physical change

a change in a substance that does not change its chemical makeup

chemical change

a change in a substance that produces one or more new substances (a chemical reaction)

polar molecules

covalently bonded molecules where electrons are shared unequally

solubility

the ability of a substance to dissolve in another substance

hydrogen bond

attractive force between water molecules caused by water's polarity that leads to many special properties of water

special properties of water

cohesion, adhesion, heat capacity, evaporative cooling, density of ice, solubility

cohesion

attractive force that holds molecules of a single substance together, the ability of a substance to stick to itself

adhesion

attractive force between particles of different substances

capillarity

attraction between molecules resulting in rise of the surface of a substance when in contact with a solid

heat capacity

the ability of a substance to absorb and release thermal energy with minimal change in energy

evaporative cooling

the process where, as a liquid evaporates, its remaining surface cools due to energy absorption

density

amount of mass per unit of volume

density of ice

result of hydrogen bonding in solid water, allows ice to float

solution

mixture in which one or more substances are evenly distributed in another substance

solute

a substance that is dissolved in a solution

solvent

the substance that solutes are dissolved in in a solution

hydrophobic

does not easily dissolve in water

hydrophilic

dissolves easily in water

aqueous solution

a solution where water is the solvent

acidity

relative measure of available hydrogen -1 atoms (protons) in an aqueous solution

alkalinity

relative amount of available hydroxide atoms in an aqueous solution

acid

a solution with more available protons (hydrogen) than hydroxide ions and a pH <7

base

a solution with more available hydroxide ions than protons (hydrogen) and a pH >7

neutral

solution with an equal amount of available hydrogen and hydroxide and a pH of 7

pH scale

logarithmic scale used to compare concentrations of single protons and hydroxide in an aqueous solution

buffers

compounds within the body that neutralize small amounts of ingested acids or bases