Chapter 3: Chemical Compounds

Polyatomic Ion

a combination of two or more covalently bonded atoms that exists as an ion; two or more atoms are joined together by covalent bonds

Molecular Compound

a compound comprised of discrete molecules

Inorganic Compounds

any combination of elements that does not fit the category of organic compound

Binary Compounds

compounds composed of two elements

Ternary Compounds

comprised of three elements (hydrogen and two nonmetals)

Alcohols

contain the functional group -OH and have the general formula ROH (class of organic molecules)

Carboxylic Acid

has one or more carboxyl groups attached to a hydrocarbon chain or ring structure

Alkanes

hydrocarbon molecules that have only single covalent bonds between carbon atoms

Alkenes

hydrocarbons that have one or more carbon-to-carbon double bonds in their molecules

Structural Formula

indicates which atoms in a molecule are bonded together, and whether by single, double, or triple bonds (covalent bonds represented by lines or dashes (-))

Covalent Bonds

involve a sharing of electrons between atoms; give rise to molecular compounds

Ionic Bonds

involve a transfer of electrons from one atom to another; give rise to ionic compounds

Organic Compounds

made up of carbon and hydrogen or carbon, hydrogen and a small number of other elements, such as oxygen, nitrogen, and sulfur

Oxidation State (Oxidation Number)

relates to the number of electrons an atom loses, gains, or shares in combining with other atoms to form molecules or polyatomic ions (oxidation state of an atom can vary, depending on the compound in which it occurs)

Chemical Formula

represents the relative numbers of atoms of each kind in a substance through symbols and numerical subscripts (indicates the elements present and the relative number of atoms of each element)

Line-Angle Formula (Line Structure)

shorthand representations of organic molecules in which bond lines are drawn, but chemical symbols are written only for elements other than carbon and hydrogen (lines represent chemical bonds)

Formula Unit

smallest collection of atoms or ions from which the empirical formula of a compound can be established (smallest electrically neutral collection of ions; ratio of atoms (ions) is the same as in the chemical formula; does not exist as a distinct entity)

Mass Composition of a Compound

the collection of mass percentages of the individual elements in the compound

Formula Mass

the mass of a formula unit of a compound, relative to a mass of exactly 12u for carbon-12 (in amu)

Molecular Mass

the mass of a molecule in atomic mass units; the mass of a molecule relative to a mass of exactly 12u for carbon-12

Molar Mass (M)

the mass of one mole of atoms, formula units, or molecules of a substance (one mole of molecules of a molecular compound and one mole of formula units of an ionic compound)

Empirical Formula

the simplest chemical formula that can be written for a compound, that is, having the smallest integral subscripts possible (subscripts reduced to their simplest whole-number ratio)

Isomers

two or more compounds having the same formula but different structures and therefore different properties

Ionic Compound

a compound consisting of positive and negative ions that are held together by electrostatic forces of attraction (atoms of metallic elements tend to lose one or more electrons when they combine with nonmetal atoms, and the nonmetal atoms tend to gain one or more electrons (metal atom becomes a positive ion, or cation (a positively charged ion; a cation migrates toward the cathode in an electrochemical cell); nonmetal atom becomes a negative ion, or anion (a negatively charged ion; an anion migrates toward the anode in an electrochemical cell)

Hydrocarbons

a compound containing the two elements carbon and hydrogen; the C atoms are arranged in straight or branched chains or ring structures

Hydrate

a compound in which a fixed number of water molecules is associated with each formula unit

Molecule

a group of bonded atoms held together by covalent bonds and existing as a separate entity; a molecule is the smallest entity having the characteristic proportions of the constituent atoms present in a substance

Condensed Structural Formula

a simplified representation of a structural formula (written on a single line; can be used to show how a group of atoms is attached to another atom)

Oxoacid

an acid in which an ionizable hydrogen atom(s) is bonded through an oxygen atom to a central atom, that is E-O-H. Other groups bonded to the central atom are either additional - OH groups or O atoms (or in a few cases H atoms)

Functional Group

an atom or grouping of atoms attached to a hydrocarbon residue, R; the functional group often confers specific properties to an organic molecule

Molecular Formula

denotes the numbers of the different atoms present in a molecule (based on an actual molecule of a compound; in some cases, the empirical and molecular formulas are identical, and in other cases, the molecular formula is a multiple of the empirical formula; empirical and molecular formulas tell us the combining ratio of the atoms in the compound)