Glossary

Glossary of Chemistry Definitions
//Students are invited to update this document for extra credit. Please *do not* copy/paste definitions from other websites - this is plagiarism! Feel free to use definitions given in class, or write *in your own words* any definitions you learn from reading a book or website. Plagiarized definitions will be removed.//

Absolute Zero –The temperature below which a substance would have zero kinetic energy Acid – a substances that produces hydronium ions when dissolved in water. pH definition – A mathematical scale in which the concentration of hydronium ions in a solution in expressed as a number from 0 to 14. Arrhenius definition – Brønsted-Lowry definition – Air Pressure – Alkali Metals – Alkaline Earth Metals – Alloy – a solid solution containing different metals, and sometimes nonmetallic substances. Alpha (α) Decay – Anion – a negative ion. Aqueous – a solution in which the solvent in water. Atom – the smallest particle of a given type of matter. Atomic Mass – Atomic Number – the number of protons in the nucleus of an atom of an element. Avagadro’s Hypothesis – Base – a substance that produces hydroxide ions when it dissolves in water. pH definition – Arrhenius definition – Brønsted-Lowry definition – Beta (β) decay – Boiling – Bonded Pair – Boyle’s Law – at a constant temperature, the volume and pressure equals the pressure exerted on its surface. Calorie – the heat required to raise the temperature of 1 gram of liquid water by 1*C. Catalyst – a substance that speeds up the rate of a reaction without being used up itself or permanently changed. Cation – a positive ion. Charles’ Law – Chemical Bond – Chemical Change – When a change occurs and it becomes a new substance. Chemical Equation – Chemical Property – Chemical Reaction – Coefficient – a number placed in front of the parts of a chemical equation to indicate how many are involved; always a positive whole number. Combination – Combined Gas Law – the combination of Boyle's law and Charles's law. Combustion – term for a reaction in which a substance rapidly combines with oxygen to form one or more oxides. Compound – a chemical combination of two or more different elements joined together in a fixed proportion. Concentration – the amount of a substance present in a unit volume. Condensation – the process where gaseous particles some together, that is, condense, to form a liquid or sometimes a solid. Conductivity – a measure of how easily electrons can flow through a material to produce an electrical current. Covalent Bond – the attraction of two atoms for a shared pair of electrons. Decomposition – the name applied to a reaction where a compound breaks down into two or more simpler substances. Density – the amount of matter (mass) in a given unit volume. Diatomic Molecule – Difference in Electronegativity (ΔEN) – Dipole – Directly Proportional – Dissociation – the process by which the charged particles in an ionic solid separate from one another, primarily when going into solution. Double Displacement – the type of reaction where the positive and negative portions of two ionic compoe.unds are interchanged; at least one product must be water or a precipitat Electron – negatively-charged particle. Electron Cloud – the space around the nucleus of an atom where, the atom's electons are found. Electron Domain – Electronegativity – the measure of the ability of an atom in a bond to attract electrons. Element – a substabce that cannot be broken down into simpler substances. Endothermic – chemical reaction that absorbs energy. Endpoint – Energy Levels – the regions of space in which electrons can move about the nucleus of an atom. Equilibrium – term for a system where no net change occurs in the amount of reactants or products. Evaporation – the process by which particles of a liquid form a gas by escaping from the liquid surface. Exothermic – chemical reaction that gives off energy. Explosion – Fire – Formula – a combination of chhemical symbols that show what elements make up a compound and the number of atoms of each element. Freezing – Fuel – Functional Group – the part of a molecule that is largely responsible for the chemical behavior of the molecule. Alcohol Amine Carboxylic acid Ester Ketone Gamma Ray – a high energy form of electronmagnetic radiation with no charge and no mass. Gas – a flowing, compressible substance with no definite volume or shape. Gay-Lussac’s Law – Group – Vertical columns on the periodic table labeled 1-18. Half-Life – the time it takes for half of a given radioactive isotope to decay. Halogens – any element from group 17 : flourine, chlorine , bromine, iodine , astatine. Heat – the energy transferred from an obkect at high temperature to an object at lower temperature. Heterogeneous Mixture – Homogeneous Mixture – HONC 1234 Rule – Hydrogen Bond – a connection between the hydrogen atoms on one molecule and a highly electronegative atom on another molecule, but not a full covalent bond. Ideal Gas Law – Indicator – Inner Transition Elements – one of the elements in the two rows of elements below the main body of the periodic table; the landthanides and the actinides. Insoluble – Inversely Proportional – Ion – an atom or group of combined atoms that has a charge because of the loss or gain of electrons. Ionic Bond – the strong attractive force between ions of opposite charge. Ionizing Radiation – Isomer – a compound with a structure different from another compound with the same formula. cis – trans – Isotope – any of two or more atoms of an element that are chemically alike but have different masses. Intermolecular Attraction – Kelvin Scale – the temperature scale defined so that temperature of a substance is directly proportional to the average kinetic energy of the particles and so that zero on the scale corresponds to zero kinetic energy. Kinetic Theory – the theory that states that submicroscopic particles of all matter are in constant, random motion. Law Of Conservation Of Matter – Lethal Dose – Lewis Dot Structure – Limiting Reactant – the reactant of which there is not enough; when it is used up, the reaction stops and no new product if formed. Liquid – a flowing substance with a definite volume but an indefinite shape. Logarithmic – Lone Pair – Main Group Elements – Mass – the measure of the amount of matter an object contains. Matter – anything that takes up space and has mass. Melting – Metallic Bond – the bond that results when metal atoms release their valence electrons to a pool of electrons shared by all the metal atom. Metalloid – an element with some physical and chemical properties of metals and other properties of nonmetals. Metals – an element that has luster, conducts heat electricity and usually bends without breaking. Molar Mass – the mass of one mole of a pure substance. Molar Volume – the volume that a mole of gas occupies at a pressure of one atmosphere and a temperature of 0.00 C. Molarity – Mole – the unit used to count numbers of atoms, molecules, or formula unites of substances. Mole Ratio – Molecule – am imcjarhed group of two or more atoms held together by covalent bonds. Neutral – pH definition – Arrhenius definition – Brønsted-Lowry definition – Neutralization –the reaction of an acid with a base, so called because the properties of both the acid and base are diminishedor neutralized. Neutron – a subatomic particle with a mass equal to a proton but with no electrical charge. Noble Gas – an element from group 18 that has a full compliment of valence electrons and as such is unreactive. Non-Metal – an element that in general does not conduct electricity, is a poor conductor of heat, and is brittle when solid. Many are gases at room temperature. Non-Polar – Non-Polar Covalent Bond – Nuclear Fission – the process in which an atomic nucleus splits into two or more large fragments. Nuclear Reaction – the device used to extract energy from a radioactive fuel. Nucleus – the small, dense, positively charged central core of an atom. Octet Rule – tge model of chemical stability that states that atoms become stable by having eight electrons in their outer energy level except for some of the smallest atoms which have only two electrons. Oxidation Number – the charge on an ion or an element can be postitive or negative. Period – Horizontal rows on the periodic table labeled 1-7. pH – a mathematical scale in which the concentration of hydronium ions in a solution is expressed as a number fromm 0 - 14. Phase – Phase Change – Phase Diagram – Physical Change – Alters the appearance of a substance but does not change identity. Physical Property – A characteristic or description that may be measured. pOH – Polar – Polar Covalent Bond – a bond where the electrons are shared uneuqally, there is some degree of ionic character to this type of bond. Polarity – Polyatomic Ion – an ion that consists of two or more different elements. Precipitate – Pressure – the force acting on a unit area of a surface. Products – a new substance formed when reactants undergo chemical change. Proton – a positively charged subatomic particle. Radioactivity – The breakdown of a nucleus. Reactants – a substance that undergoes a reaction. Reaction Rate – Reactivity – The degree to which a substance can react with another substance. Receptor Site Model – Shapes of Simple Molecules – Tetrahedron Shape – Pyramid Shape – Bent Shape – Linear Shape – Triangular Plane Shape – Shapes of Smell Molecules – Ball Shape – Flat Shape – Stringy Shape – Shell – Single Displacement – a ty[e pf reaction where one element takes the place of another in a compound. Solid – a substance in which the particles occupy fixed positions in a well defined, three dimensional arrangement. Solidification – Solubility – Soluble – term describing a substance that dissolves in a liquid. Solute – the substance that is being dissolved when making a solution. Solution – a mixture that is the same thorughout, or homogeneous. Solvent – the substance that dissolves the solute when making a solution. Specific Heat Capacity – Stoichiometry – a study of relationships between measurable quantities, such as mass and volume, and the number of atoms in chemical reactions. STP – Structural Formula – Sublimation – the process by which particles of a solid escape from its surface and form a gas. Subscript – Temperature – the measure of the average kinetic energy of the particles that make up a material. Titration – the process of determining the molarity of an acid or base by using an acid-base reaction where one reactant is of known molarity. Transition Elements – Electrons in the outermost shell. Elements in the same group have same number of valence electrons. Valence Electron – an electron in the outermost energy level of an atom. Volume – The amount of space that a substance takes up. Measured in mL using a graduated cylinder.