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Matter, Atoms, and Bonds



a negatively charged ion


the smallest unit of an element that still retains the chemical properties of the element

atomic nucleus

the core of an atom that contains protons and neutrons

atomic number

the number of protons in an atom

atomic orbital

a region around the atomic nucleus where electrons are found


a positively charged ion

chemical equilibrium

a state of balance in which forward and reverse chemical reactions are happening at the same rate

chemical reaction

a process that occurs when two or more atoms form chemical bonds or when chemical bonds between atoms break

chemical symbol

a one- or two-letter symbol used to identify an element on the periodic table


a substance made of atoms of two or more elements bonded together in a certain ratio

covalent bond

a chemical bond that forms when atoms share electrons


a negatively charged subatomic particle that moves in orbitals around the atomic nucleus


the tendency of an atom to attract electrons


a substance that cannot be broken down into simpler substances by chemical reactions

equilibrium constant

a number that expresses the relationship between the amounts of products and reactants present when a reversible chemical reaction is in balance

hydrogen bond

a weak bond between two molecules that results from an attraction between a proton in one molecule and an electronegative atom in the other


a charged particle formed when an atom gains or loses electrons

ionic bond

a chemical bond that forms when valence electrons are transferred between atoms

London dispersion force

the weakest intermolecular force that forms due to attraction between molecules

mass number

a value that is equal to the number of protons and neutrons in an atom


any substance that occupies space and has mass


a group of two or more atoms bonded together


a subatomic particle that has no charge

nonpolar covalent bond

a covalent bond that forms when two atoms share electrons equally

octet rule

a rule that states that atoms react by gaining or losing electrons in order to form the most stable electron valence structure

polar covalent bond

a covalent bond that forms from an unequal sharing of electrons between atoms


a substance formed as the result of a chemical reaction


a subatomic particle that has a positive charge


a substance that reacts in a chemical reaction

valence shell

the outermost electron shell of an atom, where valence electrons are found