Molecules and Molecular Compounds Section 2.6 Molecules and Molecular Compounds

Remember… Atoms are the smallest representative sample of an element Building Blocks of Matter! BUT- only the noble gases are found as isolated atoms The rest exist as molecules or ions

Molecules Assembly of two or more atoms tightly bound together, behaving as a single object

Chemical Formula Notation that uses chemical symbols and subscript notation to convey relative proportions of atoms of elements in a molecule

Diatomic Molecule Molecule composed of two atoms Elements normally occurring as diatomic: Hydrogen (H2) Oxygen (O2) Nitrogen (N2) The halogens (F2, Cl2, Br 2, I2)

Most molecular compounds contain only nonmetals!! Compounds composed of molecules Contain more than one type of atom Examples: CH4, H2O, H2O2 Most molecular compounds contain only nonmetals!!

Molecular Formula Indicate the actual numbers and types of atoms in a molecule. Empirical Formula Only give the relative number of atoms of each type in a molecule. Subscript is always the smallest possible whole-number ratio

Examples

Now You Try…

Does the converse hold true? If we know the molecular formula, we can determine the empirical formula! Does the converse hold true?

Structural Formula Shows which atoms are attached to each other within a molecule Atoms are represented by their chemical symbol Lines represent bonds Do not depict the geometry of the molecule (the angles of the bonds)

Acetone

Perspective Drawings Structural formula that gives a sense of the three-dimensional shape of a molecule Methane

Ball-and-stick models Shows atoms as spheres and bonds as sticks Accurately represents angles of the bonds Also demonstrates relative size of atoms Water

Space-filling models Water Depict a molecule scaled up to size Show relative size of atoms Difficult to see the angles of the bonds Water