Question | Answer |
Law of Conservation of Mass | the principle that matter cannot be created or destroyed. |
Physical Change | a usually reversible change in the physical properties of a substance, as size or shape |
Chemical Change | a usually irreversible chemical reaction involving the rearrangement of the atoms of one or more substances and a change in their chemical properties or composition, resulting in the formation of at least one new substance |
Element | one of a class of substances that cannot be separated into simpler substances by chemical means |
Chemical Formula | a representation of a substance using symbols for its constituent elements |
Element (Diatomic) Molecule | having two of the same atoms in the molecule |
Compound Molecule | a pure substance composed of two or more elements whose composition is constant |
Chemical Equation | a representation of a chemical reaction using symbols of the elements to indicate the amount of substance, usually in moles, of each reactant and product |
Chemical Reaction | A rearrangement of the atoms or molecules of two or more substances that come into contact with each other, resulting in the formation of one or more new substances. |
Reactants | any substance that undergoes a chemical change in a given reaction |
Products | a substance obtained from another substance through chemical change |
Coefficient | States the number of molecules of the certain molecule it is in front of |
Subscript | Number written under the certain atom, states the number of atoms of the element it is underneath |
Ionic Compound | a chemical compound of cations and anions which are held together by ionic bonds in a lattice structure |
Covalent Compound | A compound made of molecules- not ions. The atoms in the compound are bound together by shared electrons. Also called a molecular compound. |
Metallic Compound | Compounds that contain at least one metallic element. |
Synthesis | the forming or building of a more complex substance or compound from elements or simpler compounds. |
Decomposition | A reaction in which a compound is broken down into simpler compounds or elements. Compounds sometimes decompose if heated strongly or if subjected to a strong electric current |
Single Replacement | A reaction of the form A + BC = B + AC. For example, zinc displaces hydrogen from hydrochloric acid in the following reaction: Zn(s) + 2 HCl(aq) = ZnCl2(aq) + H2(g). |
Double Replacement | A double displacement or metathesis is a reaction in which two reactants trade fragments:
AB + CD = AC + BD
Most commonly, the fragments are ions, e. g.
AgNO3(aq) + NaCl(aq) = AgCl(s) + NaNO3(aq) |