Unit 2: Chemical Formulas and Composition Stoichiometry

A set of vocabulary flashcards covering chemical formulas, types of compounds, moisture, and stoichiometric composition based on Unit 2 lecture notes.

Atoms

The smallest stable particles of an element.

Molecules

Combinations of $2$ or more atoms.

Compounds

Combinations of $2$ or more elements.

Metals

The elements to the left of the stair steps in the periodic table, except $H$.

Non-metals

Include hydrogen and the elements to the right of the stair steps in the periodic table.

Chemical formulas

Symbols that show the types and numbers of elements that exist in a compound (ionic or covalent).

Formula units

Chemical formulas for ionic compounds.

Ionic compounds

Compounds composed of metals and non-metals that exist as extended arrays of oppositely charged particles rather than discrete molecules.

Molecular formulas

Chemical formulas for covalent molecules.

Covalent molecules

Molecules composed of only non-metals.

Ions

An atom or group of atoms with an electrical charge.

Cations

Ions with a positive charge, for example, $Ca^{2+}$ or $NH_4^+$.

Anions

Ions with a negative charge, for example, $S^{2-}$ or $F^-$.

Monatomic ions

Single atoms with an electrical charge, such as $Ca^{2+}$ or $F^-$.

Polyatomic ions

A group of atoms with an electrical charge, such as $NH_4^+$ or $PO_4^{3-}$.

The Mole ($mol$)

The SI unit used to express numbers of atoms in everyday numbers, representing $6.022 \times 10^{23}$ particles.

Avogadro's number ($N$)

The value $6.022 \times 10^{23}$, representing the number of particles in one mole.

Molar mass

The mass of $1$ mole of atoms or compounds, calculated by summing the molar masses of individual atoms and expressed in $g\,mol^{-1}$.

Atomic mass units ($\text{amu}$)

The unit used to express the mass of individual particles when it is not practical to use grams.

Formula mass (weight)

The molar mass specific to an ionic compound.

Molecular mass (weight)

The molar mass specific to a covalent compound.

Empirical formulas

The simplest whole number ratio of elements in a compound.

Hydrocarbons

Compounds containing only carbon ($C$) and hydrogen ($H$).

Combustion analysis

A method used to determine the empirical and molecular formulas of organic compounds by burning them and trapping the $CO_2$ and $H_2O$ produced.