Atoms, Molecules, and Ions Study Set

Vocabulary flashcards covering the fundamental laws of chemistry, atomic theory, subatomic particles, subatomic masses, periodic trends, and IUPAC nomenclature rules for ionic, molecular, and acidic compounds.

Law of conservation of mass

A law formulated by Antoine Lavoisier stating that mass is neither created nor destroyed in a chemical reaction.

Law of definite proportion

A principle stating that a given chemical compound always contains the same elements in the exact proportions by mass.

Law of multiple proportions

When two elements form a series of compounds, the ratios of the masses of the second element that combine with $1\,g$ of the first element can always be reduced to small whole numbers.

Dalton's Atomic Theory

A theory consisting of four postulates: elements are made of atoms; atoms of a given element are identical while those of different elements are different; compounds form when atoms combine in fixed ratios; and chemical reactions involve the reorganization of atoms.

Atom

The smallest identifiable unit of an element, consisting mostly of empty space with a very tiny, very dense nucleus.

Proton

A subatomic particle with a mass of $1.672 \times 10^{-27}\,kg$ ($1.00727\,amu$) and a relative charge of $+1$.

Neutron

A subatomic particle with a mass of $1.674 \times 10^{-29}\,kg$ ($1.00866\,amu$) and no electric charge ($0$).

Electron

A subatomic particle with a mass of $9.109 \times 10^{-31}\,kg$ ($0.000548\,amu$) and a relative charge of $-1$.

Atomic number ($Z$)

The number of protons in an atom, which defines the identity of an element.

Mass number ($A$)

The total number of protons and neutrons in an atom.

Ion

A charged particle resulting from a change in the number of electrons possessed by an atom, where the number of protons does not equal the number of electrons.

Cation

A positively charged ion formed when an atom loses an electron, where the number of protons is greater than the number of electrons ($\#p > \#e^-$).

Anion

A negatively charged ion formed when an atom gains an electron, where the number of protons is less than the number of electrons ($\#p < \#e^-$).

Chemical bonds

The forces that hold atoms together in compounds.

Covalent bonds

Chemical bonds formed by the sharing of electrons between atoms.

Molecule

A collection of atoms held together by covalent bonds.

Electronegativity

A measure of the ability of an atom in a chemical bond to attract and bind with electrons.

Polar covalent bonds

Bonds that exhibit induction causing the formation of partial positive and negative charges because one atom attracts electrons more than the other.

Metals

Substances characterized as good conductors of heat and electricity, malleable, ductile, lustrous, and having a tendency to lose electrons to become cations.

Nonmetals

Substances that are not conductive, not malleable, and not lustrous; they tend to gain electrons to become negatively charged anions.

Atomic radius

The distance from the center of an atom's nucleus to the outermost boundary of its electron cloud.

Effective nuclear charge ($Z_{eff}$)

The actual amount of positive charge experienced by an electron in a multi-electron atom, calculated as $Z_{eff} = \#P - \#\text{core } e^-$.

Ionization energy

The energy required to remove an electron from a gaseous atom or ion.

Electron affinity

The amount of energy released when an electron is added to a neutral atom or molecule to form a negative ion.

Binary Compound (Type I)

An ionic compound formed from a metal that only forms one type of cation and a nonmetal.

Polyatomic ions

Ions consisting of multiple atoms assigned special names that must be memorized.

Acid (naming rule: no oxygen)

An acid is named with the prefix "hydro-" and the suffix "-ic" if the anion does not contain oxygen.

Acid (naming rule: -ate anion)

If the anion name ends in "-ate", the suffix "-ic" is added to the root name of the anion to form the acid name.

Acid (naming rule: -ite anion)

If the anion name ends in "-ite", the suffix "-ous" replaces the "-ite" ending to form the acid name.