13 Key Terms
- acid
- molecule that donates hydrogen ions and increases the concentration of hydrogen ions in a solution
- acidic
- possessing a pH < 7.0
- adhesion
- attraction between water molecules and other molecules
- alkaline
- possessing a pH > 7.0
- aliphatic hydrocarbon
- hydrocarbon consisting of a linear chain, branched chain, or non-aromatic ring of carbon atoms
- anion
- negative ion that is formed by an atom gaining one or more electrons
- aromatic hydrocarbon
- hydrocarbon consisting of closed rings of carbon atoms with alternating single and double bonds
- atom
- the smallest unit of matter that retains all of the chemical properties of an element
- atomic mass
- calculated mean of the mass number for an element’s isotopes
- atomic number
- total number of protons in an atom
- balanced chemical equation
- statement of a chemical reaction with the number of each type of atom equalized for both the products and reactants
- base
- molecule that donates hydroxide ions or otherwise binds excess hydrogen ions and decreases the hydrogen ions’ concentration in a solution
- buffer
- substance that resists a change in pH by absorbing or releasing hydrogen or hydroxide ions
- calorie
- amount of heat required to change the temperature of one gram of water by one degree Celsius
- capillary action
- occurs because water molecules are attracted to charges on the inner surfaces of narrow tubular structures such as glass tubes, drawing the water molecules to the tubes’ sides
- cation
- positive ion that is formed by an atom losing one or more electrons
- chemical bond
- interaction between two or more of the same or different atoms that results in forming molecules
- chemical reaction
- process leading to rearranging atoms among molecules
- chemical reactivity
- the ability to combine and to chemically bond with each other
- cohesion
- intermolecular forces between water molecules caused by the polar nature of water; responsible for surface tension
- compound
- substance composed of molecules consisting of atoms of at least two different elements
- covalent bond
- type of strong bond formed between two atoms of the same or different elements; forms when electrons are shared between atoms
- dissociation
- release of an ion from a molecule such that the original molecule now consists of an ion and the charged remains of the original, such as when water dissociates into H+ and OH–
- electrolyte
- ion necessary for nerve impulse conduction, muscle contractions, and water balance
- electron
- subatomic particle of inconsequential mass that resides outside of the nucleus in an electron orbital; has −1 charge
- electron configuration
- arrangement of electrons in an atom’s electron shell (for example, 1s22s22p6)
- electron orbital
- how electrons are spatially distributed surrounding the nucleus; the area where we are most likely to find an electron
- electron transfer
- movement of electrons from one element to another; important in creating ionic bonds
- electronegativity
- ability of some elements to attract electrons (often of hydrogen atoms), acquiring partial negative charges in molecules and creating partial positive charges on the hydrogen atoms
- element
- one of 118 unique substances that cannot break down into smaller substances; each element has unique properties and a specified number of protons
- enantiomers
- molecules that share overall structure and bonding patterns, but differ in how the atoms are three dimensionally placed such that they are mirror images of each other
- equilibrium
- steady state condition of balanced forward and backward progress in reversible chemical reactions
- evaporation
- change of water from liquid to gaseous state, often removing heat from a wet surface
- functional group
- group of atoms that provides or imparts a specific function to a molecule with a carbon skeleton
- geometric isomer
- isomer with similar bonding patterns differing in the placement of atoms alongside a double covalent bond
- heat of vaporization of water
- high amount of energy required for liquid water to turn into water vapor
- hydrocarbon
- molecule that consists only of carbon and hydrogen
- hydrogen bond
- weak bond between slightly positively charged hydrogen atoms and slightly negatively charged atoms in other molecules
- hydrophilic
- describes ions or polar molecules that interact well with other polar molecules such as water
- hydrophobic
- describes uncharged nonpolar molecules that do not interact well with polar molecules such as water
- inert gas
- (also, noble gas) element with filled outer electron shell that is unreactive with other atoms
- ion
- atom or chemical group that does not contain equal numbers of protons and electrons and so bears a net charge
- ionic bond
- chemical bond that forms between ions with opposite charges (cations and anions)
- irreversible chemical reaction
- chemical reaction where reactants proceed unidirectionally to form products
- isomers
- molecules that differ from one another even though they share the same chemical formula
- isotope
- one or more forms of an element that have different numbers of neutrons
- law of mass action
- chemical law stating that the rate of a reaction is proportional to the concentration of the reacting substances
- litmus paper
- (also, pH paper) filter paper treated with a natural water-soluble dye that changes its color as the pH of the environment changes in order to use it as a pH indicator
- macromolecule
- very large molecule, biologically important
- mass number
- total number of protons and neutrons in an atom
- matter
- anything that has mass and occupies space
- molecule
- two or more atoms chemically bonded together
- neutron
- uncharged particle that resides in an atom’s nucleus; has a mass of one amu
- noble gas
- see inert gas
- nonpolar covalent bond
- type of covalent bond that forms between atoms when electrons are shared equally between them
- nucleus
- core of an atom; contains protons and neutrons
- octet rule
- rule that atoms are most stable when they hold eight electrons in their outermost shells
- orbital
- electron orbital
- organic molecule
- any molecule containing carbon (except carbon dioxide)
- periodic table
- organizational chart of elements indicating each element’s atomic number and atomic mass; provides key information about the elements’ properties
- pH paper
- see litmus paper
- pH scale
- scale ranging from zero to 14 that is inversely proportional to the hydrogen ions’ concentration in a solution
- polar covalent bond
- type of covalent bond that forms as a result of unequal electron sharing, resulting in creating slightly positive and negative charged molecule regions
- polyunsaturated fat
- fats that have more than one carbon-carbon double bond
- product
- molecule that is result of chemical reaction
- proton
- positively charged particle that resides in the atom’s nucleus; has a mass of one amu and a charge of +1
- radioisotope
- isotope that emits radiation comprised of subatomic particles to form more stable elements
- reactant
- molecule that takes part in a chemical reaction
- reversible chemical reaction
- chemical reaction that functions bidirectionally, where products may turn into reactants if their concentration is great enough
- solvent
- substance capable of dissolving another substance
- specific heat capacity
- the amount of heat one gram of a substance must absorb or lose to change its temperature by one degree Celsius
- sphere of hydration
- when a polar water molecule surrounds charged or polar molecules thus keeping them dissolved and in solution
- structural isomers
- molecules that share a chemical formula but differ in the placement of their chemical bonds
- substituted hydrocarbon
- hydrocarbon chain or ring containing an atom of another element in place of one of the backbone carbons
- surface tension
- tension at the surface of a body of liquid that prevents the molecules from separating; created by the attractive cohesive forces between the liquid’s molecules
- valence shell
- outermost shell of an atom
- van der Waals interaction
- very weak interaction between molecules due to temporary charges attracting atoms that are very close together