Atoms, Molecules, and Chemical Transformations

Vocabulary flashcards reviewing basic 4th-grade chemistry concepts including atoms, molecules, chemical formulas, and chemical transformations.

Atom

The basic constituent of molecules, modeled as a very small sphere and designated by a chemical symbol.

Chemical Symbol

A symbol associated with each type of atom, consisting of an uppercase letter optionally followed by a lowercase letter.

Periodic Table of Elements

The table that gathers all 118 known types of atoms.

Hydrogen Atom

An atom represented by the chemical symbol $H$.

Oxygen Atom

An atom represented by the chemical symbol $O$.

Nitrogen Atom

An atom represented by the chemical symbol $N$.

Carbon Atom

An atom represented by the chemical symbol $C$.

Molecule

A structure consisting of atoms bound together, modeled as an assembly of spheres.

Chemical Formula

A representation that indicates the composition of a molecule, where subscript numbers specify how many times each type of atom is present.

Dihydrogen

A molecule with the chemical formula $H_2$.

Dioxygen

A molecule with the chemical formula $O_2$.

Dinitrogen

A molecule with the chemical formula $N_2$.

Water

A molecule with the chemical formula $H_2O$.

Carbon Dioxide

A molecule with the chemical formula $CO_2$.

Methane

A molecule with the chemical formula $CH_4$.

Chemical Transformation

A process where atoms of reactant molecules rearrange to form product molecules, causing the disappearance of reactants alongside the appearance of products.

Reaction Equation

A symbolic representation of a chemical transformation process, such as $C + O_2 \rightarrow CO_2$ for the combustion of carbon.

Conservation of Atoms

The rule stating that during a chemical transformation, no atom is created or destroyed.

Balanced Reaction Equation

A reaction equation in which coefficients are placed in front of formulas to ensure the same number of each type of atom exists in reactants and products (e.g., $CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O$).

Conservation of Mass

The principle stating that during a chemical transformation, the mass of consumed reactants equals the mass of formed products.