Topic 2 Regents Chemistry Review: Nomenclature & Formula Writing

Chemical Symbols

Unique one-, two-, or three-letter symbols for elements, with the first letter capitalized.

Empirical Formula

Simplest integer ratio in which atoms combine to form a compound.

Molecular Formula

Represents the actual ratio of atoms in a molecule, may be a multiple of the empirical formula.

Ions

Electrically charged atoms, positively charged ions attract negatively charged ions to form neutral compounds.

Coefficients

Numbers in front of a formula indicating the number of units of the formula, applying to the entire formula.

Analysis

The process of breaking down a substance or a mixture to determine its composition or properties.

Chemical Change

A process where one or more substances undergo a chemical reaction, resulting in the formation of new substances with different chemical compositions.

Coefficient

A number in a chemical equation representing the stoichiometric relationship between reactants and products.

Decomposition

A type of chemical reaction where a compound breaks down into simpler substances or elements.

Diatomic Molecule

A molecule composed of two atoms of the same or different elements chemically bonded together.

Double Replacement

A chemical reaction where ions in two compounds exchange places to form two new compounds.

Empirical Formula

The simplest whole-number ratio of atoms in a compound.

Endothermic

A reaction or process that absorbs heat from its surroundings.

Exothermic

A reaction or process that releases heat into its surroundings.

Formula

A symbolic representation of a compound showing the types and numbers of atoms present.

Molecular Formula

A chemical formula that indicates the actual number of each type of atom in a molecule of a compound.

Molecule

A group of two or more atoms held together by chemical bonds.

Physical Change

A change in which the substance's physical state or appearance changes without altering its chemical composition.

Polyatomic Ion

An ion composed of two or more atoms covalently bonded together and carrying a net electric charge.

Product

A substance formed in a chemical reaction.

Qualitative

Descriptive information about properties or characteristics without numerical measurements.

Quantitative

Information about quantities or amounts, usually involving numerical measurements.

Reactant

A substance consumed in a chemical reaction to produce products.

Single Replacement

A chemical reaction where one element replaces another in a compound.

Subscript

A small number written at the lower right of a chemical symbol indicating the number of atoms of that element in a molecule.

Symbol

An abbreviation or representation of an element used in chemical formulas.

Synthesis

A chemical reaction where two or more substances combine to form a more complex product.