Nomenclature (It’s fun!!!) Ionic Binary Molecular Acids

Binary Molecular Compounds Consist of two Nonmetals. Identify where nonmetals are on the Periodic Chart. Need to know Greek prefixes! See handout!

Binary Molecular Cmpds. Cont. For the first element - Greek prefix + the element name. Omit the prefix -mono for the first element! For the second element - Greek prefix + element name with the “-ide” ending! Example: SO3 is named Sulfur Trioxide Example: N2O is named Dinitrogen Monoxide

Formulas of Binary Molecular Compounds Use the chemical formula to determine the name. The Greek prefix indicates the number of atoms of each nonmetal. Ex: Chlorine Trifluoride consists of one Chlorine atom and three Fluorine atoms so the Chemical Formula is ClF3.

Naming of Ionic compounds! First, What is an Ionic Compound? Consists of Cations (positively charged) and Anions (negatively charged) that are bonded via electrostatic attractions. Note: Coulomb’s Law Usually consist of a Metal and Nonmetal although Polyatomic Ions may be involved!

Properties of Ionic Compounds Commonly called “salts” Usually are solids at room temperature (25C) Have high melting points Dissolve in water (Soluble in water) Conduct an electric current Do not conduct as solids!

Formation of Ionic Compounds Composed of positive (metal or polyatomic ion) and negative (nonmetal or polyatomic ion) ions. Cation + Anion Are electrically neutral - The number of +’s must equal the number of -’s!!! Use subscripts to balance the charges. Called Formula Units! Are NOT called Molecules! Must know the charges of the elements or polyatomic ion! Hence, all the prior quizzes!

Writing Chemical Formulas for Ionic Compounds Positive Ions (Cations) are always written first! Combine the number of positively charged ions with the correct number of negatively charged ions in order to obtain a neutral compound. Do this by adding subscripts when necessary. When adding a subscript to a polyatomic ion, use (parenthesis) around the entire poly. Ion before adding the subscript.

Examples of Ionic Formulas Ca2+ and Cl1- yield CaCl2 : Note that the total charge on Ca of 2+ = the total charge of Cl, which is the subscript 2 times the charge of 1-, thus the compound itself is neutral! A method called the “criss cross” method can also be utilized to balance ionic compounds. Your nice teacher will now demonstrate this!

Polyatomic Ions in Formulas To combine NH4+ with CN 1- : Note that the charge of 1+ equals the charge of 1-. Therefore, the ratio for the chemical formula is 1:1. Remember, always write the cation, or positive ion, first! The final formula is NH4CN See how easy this is?

Multiple Polyatomic Ions Combine Ba2+ with NO31- : In order to get a “zero” charge, two Nitrates will be needed. When more than one polyatomic ion is needed, parenthesis must be used around the entire Poly. Ion before adding the subscript! Never use parenthesis around a monatomic ion! The correct formula for the above is therefore: Ba(NO3)2.

Naming the Ionic Compounds when given the Formula If the metal only has one charge, usually a metal from family IA, IIA or IIIA, just name the metal (cation), then the nonmetal (anion) but remember to add the -ide ending to the anion! So NaCl is named Sodium Chloride! How easy, right?

Naming with a Cation that has multiple charges Let’s say that the formula involves Iron, which can be either 2+ or 3+. To figure out the charge for Fe, one must know the charge of the anion! In FeCl3,the Chloride Ion has a charge of 1-, so the total charge for 3 Cl ions would be 3-, therefore the charge of Iron must be 3+! The name would be Iron (III) Chloride OR Ferric Chloride and yes, you must know BOTH ways to name this compound!

Naming with a Polyatomic Ion When a polyatomic ion is involved, the name of that ion stays the same! How easy! Ex: Name CaSO4: Calcium only has one charge so the name would be Calcium Sulfate (See why knowing the names of the polyatomic ions is important)?

Practice Makes Perfect Assuming that one knows the charges of the ions, naming requires a lot of practice, sorry! Therefore, there will be MANY worksheets for students to practice naming.(As well as a little lab activity) Nomenclature will continue into the next THREE chapters!