GO 4 Apply simplified chemical nomenclature in describing elements, compounds and chemical reactions 4-3Read and interpret chemical formulas for Molecular compounds canadian-eats-26-tsp-of-sugar-a-day/article600803/?service=mobile

Guided Question How do we use the information from the periodic table to write a chemical name and chemical formula for a Molecular compound ?

3.3 Molecular Compounds  Formed when non metal elements combine with each other  Molecular compounds are held together by Covalent bonds  Covalent bonds are the result of Electrons being Shared (not like ionic bonds)  Atoms in the molecular compound get their electrons to be like the nearest noble gas by sharing electrons with other atoms

Example of Covalent Bonds How many e - does oxygen have in its outer/valence level? ______ What is the nearest noble gas to oxygen? __________________ How many e - does hydrogen have? _____ What is the nearest noble gas to hydrogen? ______________________________________________________________

More About Molecular Compounds  Covalent bonds are weaker than ionic bonds So, molecular compounds have Lower boiling and melting points  Molecular compounds can be in any state at room temperature  Electrons are shared in covalent bonds and they do not move. So, molecular compounds do a good job of insulating electricity (no transfer of electrons) or (atoms can’t move very well)

Molecules Molecule – two or more atoms covalently bound together Molecule – two or more atoms covalently bound together Diatomic molecule – two of the same atom bound together Diatomic molecule – two of the same atom bound together

Diatomic Molecules Br I N Cl H O F or the Magnificent 7 Br I N Cl H O F or the Magnificent 7 These atoms never exist alone. These atoms never exist alone. They always come in pairs They always come in pairs For example: For example: –Br  Br 2 –I  I 2 –N  N 2 –Cl  Cl 2 –H  H 2 –O  O 2 –F  F 2

Naming Molecular Compounds  Molecular compounds sometimes have Chemical names that have to be memorized (ie. water is H 2 O (l) )  The Chemical name gives you the ability to determine the chemical formula  Elements are written in order of Lower group number ex. Di-hydrogen monoxide 2 hydrogens and 1 oxygen chemical formula: H 2 O (l)

Prefixes Designate The Number Of Atoms One exception to the naming rule is if the first element in the compound has only one atom then we do not use a prefix (CO = carbon monoxide and not monocarbon monoxide) decapenta nonatetra octatri heptadi hexamono Number of atoms Prefix Prefix

Put it into Practice (not used) Chemical Name none CO 2 NH 3 (sour gas) (sour gas) H2SH2SH2SH2S H2OH2OH2OH2O N2ON2ON2ON2O none NO 2 NO none NF 3 Common Name Compound