Naming Binary Covalent Compounds

Rules for naming binary molecular compounds 1. The first element in the formula is always named first simply name the element. 2. The second element in the formula is named using the root of the element and adding the suffix -ide 3. Prefixes are used to indicate the number of atoms of each type that are present in the compound.

First Example  P 2 O 5 1. What is the first element? Phosphorous 2. What is the second element? Oxygen turn it into oxide 3. What prefixes do we use? There are two phosphorouses so we use diphosphorous. There are five oxygens so we make it pentoxide. Diphosphorous pentoxide.

Second Example  Water H 2 O 1. What is the first element - hydrogen 2. What is the second element - oxygen again turn it to oxide 3. What prefixes do we use? Di for two and mono for one Dihydrogen monoxide

Third Example  NF 3 1. What is the first element? Nitrogen 2. What is the second element? Fluorine change to fluoride 3. What prefixes do we use. Since the nitrogen is first and only one we don’t need to use a prefix for it. For the Fluoride we use the prefix -tri The answer is nitrogen trifluoride

Naming Ionic Compounds Name the cation first and the anion second. Monoatomic cations use the elements name. Monoatomic anions take their name from the root of the element name plus the suffix -ide. Group 1A and 2A metals have only one oxidation number, transition metals and metals on the right side of the periodic table often have more than one oxidation number. If the compound contains a polyatomic ion simply name the ion.

Example 1  NaCl 1. Monoatomic cations use the elements name. Sodium 2. Monoatomic anions take their name from the root of the element name plus the suffix -ide. Chloride Sodium Chloride

Example 2  (NH 4 ) 3 PO 4 1. If the compound contains a polyatomic ion simply name the ion. Ions Ammonium and Phosphate Name Ammonium Phosphate

Example 3 Stock Naming Method  Fe 2 O 3 1. Transition metals and metals on the right side of the periodic table often have more than one oxidation number, determine the oxidation number of the transition metal based on the charge of the anion and write the name of the metal with the oxidation number in parenthesis. Iron (III) 2. Monoatomic anions take their name from the root of the element name plus the suffix -ide. Oxide Iron(III)Oxide