COMPOUNDSCOMPOUNDS

part two: molecular compoundspart two: molecular compounds

+ =Na Cl NaCl

Reminder: Ionic compounds involve a metalReminder: Ionic compounds involve a metal

IONIC COMPOUNDS

IONIC COMPOUNDS

and a non-metaland a non-metal

MOLECULAR COMPOUNDSMOLECULAR COMPOUNDSMolecular compounds involve two or more non-metals.

They contain covalent bonds where a pair of electrons is shared between two non-metal elements.

MOLECULAR ELEMENTS

MOLECULAR ELEMENTSA molecular element is when two

or more atoms of the same element are joined by covalent bonds.

If 2 atoms of the same element –

diatomic molecule.

If 2 atoms of the same element –

diatomic molecule.

MOLECULAR COMPOUNDSMOLECULAR COMPOUNDSBoth molecular elements and molecular compounds involve covalent bonds between non-metal atoms. For example, water is a

molecular compound with 2 covalent bonds.

Each hydrogen atom shares 1 pair of electrons with the oxygen atom.

PROPERTIESPROPERTIESMolecular compounds have unique

properties…

• Soft• Low melting points• Solutions do not conduct

electricity

NAMING MOLECULAR COMPOUNDSNAMING MOLECULAR COMPOUNDS

For compounds not containing hydrogen:

• Name the first element• Name the second

element and change the ending of the name to “ide”

• Add prefixes to show the number of each atom

NAMING MOLECULAR COMPOUNDSNAMING MOLECULAR COMPOUNDS

Using prefixes:• The prefix “mono” is not

needed if there is only one atom of the first element

• When mono is put in front of oxygen, the second “o” is dropped (monoxide instead of monooxide)

Example Problem 1:

Write the name of the molecular compound N2O

1. Name the first element:

2. Name the second element and change the ending:

3. Add prefixes to show the number of each atom:

NAMING MOLECULAR COMPOUNDSNAMING MOLECULAR COMPOUNDS

N = nitrogen

The atom is oxygen, therefore oxide

Dinitrogen monoxide

Example Problem 2:

Write the name of the molecular compound PBr3

1. Name the first element:

2. Name the second element and change the ending:

3. Add prefixes to show the number of each atom:

NAMING MOLECULAR COMPOUNDSNAMING MOLECULAR COMPOUNDS

P = phosphorous

bromide

Phosphorous tribromide

Example Problem 1:Write the chemical formula of the compound dinitrogen

tetroxide

NAMING MOLECULAR COMPOUNDSNAMING MOLECULAR COMPOUNDS

N O

N2 O4

Therefore N2O4

This cannot be simplified because it is a molecular

compound.

This cannot be simplified because it is a molecular

compound.

NAMING MOLECULAR COMPOUNDSNAMING MOLECULAR COMPOUNDS

Hydrogen is unique in many ways. Therefore, many compounds containing hydrogen have been given simple, common names.

For example, dihydrogen monoxide (H2O) is called water.