atom

basic unit of matter

nucleus

center of the atom

holds the protons and neutrons

proton

positively charged particle in an atom

has mass

identifies atoms of a particular element

neutron

no charge

has mass

can lead to isotopes of an element

electrons

negatively charged particles in an atom

determine chemical behavior

valence electrons

the electrons in the outermost electron orbital

electron orbital (shell)

area outside of the nucleus in an atom that holds the electrons

atomic number

the number of protons in the nucleus of an atom

identifies an element

atomic mass

the number of protons and neutrons in the nucleus of an atom

ion

an atom that has an unequal number of protons and electrons

neutral atom

atom that has an equal number of protons and electrons

isotope

atoms of the same element that vary by mass

(difference is due to the number of neutrons)

covalent bond

bond formed between atoms that share electrons to fill their outermost electron shell

ionic bond

when one atom gives up an electron to another atom

Creates positive and negative ions that attract each other

polar covalent bond

covalent bond where the electrons are not shared equally and create slightly positive and negatively charged ends of the molecule

compound

substance composed of two or more different elements

molecule

substance composed of two atoms bonded together

acid

a substance that releases hydrogen ions into solution

pH 0-6.9

the lower the number the stronger it is

base

a substance that releases OH- ions into solution

pH 7.1-14

The higher the number the stronger it is

Buffer

substance that bind H+ ions, or release them to maintain homeostasis

pH

measure of the H+ ions and OH- ions in a solution

solvent

substance that dissolves another material

solute

substance that is dissolved in a solution

solution

one substance dissolved in another

concentration

• amount of solute dissolved in the solvent

cohesion

attraction between the water molecules, stick together, surface tension

adhesion

attraction among molecules of different substances, water to sticking to other molecules