| A | B |
|---|
| Valence Electrons | Electrons in the outermost energy level of an atom |
| Covalent Bond | Electrons are shared between atoms |
| Ionic Bond | Electrons are transferred between atoms |
| Ion | A charged atom |
| Atom | Smallest part of an element |
| Molecule | Chemical union of two or more atoms |
| Symbol | Represents an atom or element |
| Molecular Formula | Represents a molecule or compound |
| Subscript | Tells the number of atoms of an element in a molecule |
| One | Number of atoms in the molecule if there is no subscript |
| Coefficient | Number which describes how many molecules of a substance are involved in a chemical reaction. |
| Metals | Tend to lose electrons to become stable |
| Nonmetals | Tend to gain electrons to become stable |
| Noble Gases | Very stable, do not lose or gain electrons |
| Ionic Bond | Usually occurs between metals and nonmetals |
| Covalent Bond | Usually occurs between 2 nonmetals |
| Chemical Reaction | Process in which a new substance with different physical and chemical properties is formed |
| Reactants | Substances that go into the reaction |
| Products | Substances that are produced during the reaction |
| Chemical equation | Represents a chemical reaction |
| Law of Conservation of Mass | Observation that mass remains constant in a chemical reaction |
| Balanced Equation | Number of atoms of reactants equal the number of atoms of products |
| Synthesis Reaction | Two or more simple substances combine to form a new more complex substance |
| Decomposition Reaction | A complex substance breaks down into two or more simpler substances |
| Single-Replacement Reaction | An uncombined element replaces an element that is part of a compound |
| Double-Replacement Reaction | Different atoms in two different compounds replace each other |
| Endothermic Reaction | Energy is being absorbed |
| Exothermic Reaction | Energy is being released |
| Diatomic | Elements that exist in nature as two atoms covalently bonded together |
