Introduction to Chemistry: Atomic Mass, Formulas, and Nomenclature

This flashcard set covers the essential vocabulary from lecture chapters 1-3, focusing on atomic mass, chemical formulas, periodic table organization, and chemical nomenclature.

Average Atomic Mass

The weighted average of the masses of an element's isotopes, represented by the decimal numbers found on the periodic table.

Abundance

The quantity of a specific isotope existing in nature, commonly expressed as a percentage ratio.

Periodic Table Decimals

The averages of isotope masses for an element, such as hydrogen weighing $1.008\,\text{grams per mole}$.

Atomic Mass Unit (amu)

The standard unit for expressing mass on an atomic scale, approximately equal to the mass of a single proton or neutron.

Molecular Formula

A formula that shows the actual number of each type of atom present in one molecule of a compound.

Empirical Formula

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

Structural Formula

A visual representation showing exactly how atoms in a molecule are connected to each other.

Diatomic Elements

Elements that always exist in pairs in nature: hydrogen ($H_2$), oxygen ($O_2$), nitrogen ($N_2$), fluorine ($F_2$), chlorine ($Cl_2$), bromine ($Br_2$), and iodine ($I_2$).

Subscript

A small number in a chemical formula, like the 6s in benzene ($C_6H_6$), indicating the number of atoms of that element in the molecule.

Coefficient

A large number placed before an element or formula, used for balancing equations and indicating multiple separate atoms or molecules.

Isomers

Compounds that share the same molecular formula but possess different structures.

Structural Isomers

Compounds with the same formula where atoms are connected in a different order, such as acetic acid (vinegar) and methyl formate (insecticide).

Spatial Isomers (Stereo Isomers)

Compounds with the same connectivity but different three-dimensional orientations in space.

Enantiomers

A type of spatial isomer where molecules are exact mirror images of each other, like the two forms of carvone that smell like mint or caraway seeds.

Law of Octaves

Proposed by Newlands in 1865, stating that every eighth element exhibits similar properties.

Mendeleev

The scientist who arranged the early periodic table by atomic mass and predicted the existence of elements like gallium by leaving gaps.

Moseley

The scientist who in 1913 created the modern periodic table arrangement based on atomic number (number of protons).

Periods

The seven horizontal rows on the periodic table where elements have the same number of electron shells.

Groups

The 18 vertical columns (also called families) on the periodic table containing elements with similar chemical properties.

Metals

Elements located on the left and center of the table that are shiny, malleable, ductile, good conductors, and form cations.

Metalloids

Elements along the staircase line that act as semiconductors and share properties of both metals and non-metals.

Non-metals

Dull, brittle elements located on the right side of the table that are poor conductors and form anions.

Alkali Metals

The elements in Group 1, excluding hydrogen.

Alkaline Earth Metals

The elements in Group 2 of the periodic table.

Transition Metals

The large block of elements in Groups 3 through 12, often having variable charges.

Halogens

Highly reactive non-metals in Group 17 (7A) with seven valence electrons.

Noble Gases

Stable, non-reactive elements in Group 18 (8A) possessing a full octet of electrons.

Ionic Bonds

Bonds formed when electrons are transferred from a metal to a non-metal, resulting in electrostatic attraction between cations and anions.

Covalent Bonds

Bonds formed between two non-metals that share electron pairs equally.

Binary Molecular Compounds

Covalent compounds made of two non-metals that use Greek prefixes (mono-, di-, tri-, etc.) in their names.

Polyatomic Ions

Charged molecules consisting of multiple atoms that stick together as a single unit or group.

Variable Charged Metals

Transition metals that can have different oxidation states, requiring Roman numerals in their names to indicate the specific charge.

Ionic Hydrates

Ionic compounds that trap a specific number of water molecules within their structure, such as copper sulfate pentahydrate.

Binary Acids

Acids consisting of hydrogen and one other non-metal, named with 'hydro-' prefix and '-ic' suffix (e.g., hydrochloric acid).

Oxoacids

Acids containing hydrogen and a polyatomic ion with oxygen; suffix changes include '-ate' becoming '-ic' and '-ite' becoming '-ous'.

Density Formula

$$\text{Density} = \frac{\text{mass}}{\text{volume}}$$