Binomial Nomenclature

2 types of chemical compounds that we will name: Binary ionic - metal ion – nonmetal ion Binary molecular - two nonmetals

Tips to keep in mind when naming and writing formulas: Always keep your Periodic Table handy! Metals (except Hydrogen) are found to the left of the stairstep on the Periodic Table. Nonmetals are found on the right side of the Periodic Table. Transition Metals are found to the right of Group 2 to the stairstep (except aluminum which is a regular metal)

Naming Binary Ionic Compounds When naming, metals always come before the non-metal (Al and F) If the first ion is a transition element other than zinc, cadmium, or silver, you must use a Roman Numeral with the name – we’ll discuss this later. Name the first element as is and follow with the second element ending in “ide”

Name the nonmetal ion, changing the suffix to –ide. Examples NaCl Name the metal ion Sodium Chloride Name the nonmetal ion, changing the suffix to –ide. CaO Calcium Oxide Al2S3 Aluminum Sulfide MgI2 You should recognize a problem with this one Magnesium Iodide This is two metals – not a binary ionic compound. The name of this is Banana (JOKE – haha) BaNa2

Notice – metal and nonmetal. What about the transition metals and using roman numerals? How does that work? Let’s see. FeO Notice – metal and nonmetal. Name the first ion. Since the first ion is a transition element, you must use a Roman Numeral to represent the charge. Iron II Oxide How do you know the charge? Deductive reasoning. All compounds are neutral. Oxygen has a -2 charge (group 16) Therefore ….. Iron must have a +2 charge since there is one iron and one oxygen. Iron gets a Roman Numeral II. Isn’t this easy and FUN!!!

Name the first ion. Since it is a transition metal, you must use a Roman Numeral. Which Roman Numeral? The Roman Numeral is the same as the charge of the ion. How do you find the charge? Deductive reasoning! All compounds are neutral Sulfur has a -2 charge (group 16) There are two coppers. Therefore each copper must have a +1 charge for all ions to be neutral Cu2S Copper (I) Sulfide

So why must we use Roman Numerals with transition elements? The metals in groups 1, 2, and 3 have single, definite charges. Group 1 metals have a +1 charge. Group 2 metals have a +2 charge. Group 13 metals have a +3 charge. Transition metals may have multiple charges – usually two different positive charges. For example, there are two copper oxide compounds: CuO Copper (II) oxide Copper is +2 Cu2O Copper (I) oxide Copper is +1 Cu2O and CuO We can’t just say Copper oxide. Which one of these is Copper oxide? We must distinguish these by using a Roman Numeral

You need to remember the charges for these. There are three transition elements which do not require a Roman Numeral because they have single definite charges. These are: Zinc – Zn+2 Cadmium – Cd+2 Silver – Ag+1 You need to remember the charges for these. No Roman Numerals needed for these. Ag2O Name the first ion. Name the second ion changing the suffix to –ide. Silver oxide ZnCl2 Name the first ion. Name the second ion changing the suffix to –ide. Zinc chloride

The –ous suffix name corresponds with the smaller charge. Sometimes you will see the transition elements named using common names. Transition metals named with Roman Numerals involves stock names. The common names use the Latin derivative of the element’s name with a suffix of either –ous or –ic. The –ous suffix name corresponds with the smaller charge. The –ic suffix name corresponds with the larger charge. Cuprous = Copper (I) Cupric = Copper (II) Ferrous = Iron (II) Ferric = Iron (III) Plumbous = Lead (II) Plumbic = Lead (IV) There are many more – just be familiar with these six common names.

In Summary Stock name Common Name Copper I Cuprous Copper II Cupric Iron II Ferrous Iron III Ferric Lead (II) Plumbous Lead (IV) plumbic

The Next Category of Compounds – Binary Molecular These compounds contain two elements (binary). The term “molecular” indicates that these elements are joined by a covalent bond. They must therefore be nonmetals. Bottom line – 2 elements – both nonmetals To name and write formulas for these, you must know some numerical prefixes.

Naming Covalent Bonds To name covalent compounds we use numerical prefixes to tell the # of atoms of each element in a molecules. Exception- Don’t use mono- before the first element Wrong- CO- monocarbon monoxide Correct- CO- carbon monoixde Just like ionic bonds, the ending of the second element is still changed to “ide”. Prefix Mono Di Tri Tetra Penta Hexa Hepta Octa Nona Deca Number 1 2 3 4 5 6 7 8 9 10

Dinitrogen tetraoxide CCl4 Carbon tetrachloride CO2 Carbon dioxide CO Carbon monoxide N2O4 Dinitrogen tetraoxide CCl4 Carbon tetrachloride Name the first element. Since there is only one, no prefix is needed. The second element always gets a prefix and a suffix of –ide. Name the first element. Since there are two present, the prefix “di” is needed. The second element always gets a prefix and a suffix of –ide.

AlCl3 What do you think about this one??? Be careful. This is a metal and nonmetal. Always keep your Periodic Table in front of you for reference. You may have been tempted to say “aluminum trichloride”. This is INCORRECT! This is a binary IONIC compound. No prefixes are used. Simply aluminum chloride.

SiO2 P2Cl5 Silicon dioxide Diphosphorous pentachloride Silicon and oxygen are both nonmetals. The lack of a prefix on silicon means that there is only ONE silicon. The prefix “di” in front of oxide means that there are TWO oxygens. SiO2 Diphosphorous pentachloride P2Cl5 Phosphorous and chloride are both nonmetals. The prefix “di” means that there are TWO phosphorouses (Is that a word?) The prefix “penta” before chlorine means that there are five chlorines.

CCl4, Carbon tetrachloride S, O S, F C,Cl N,I SO2, sulfur dioxide SF2,sulfur difluoride CCl4, Carbon tetrachloride NI3,Nitrogen triiodide You Try!

NO Is this not sooooooo easy!?? Nitrogen monoxide Nitrogen and oxygen are both nonmetals. The lack of a prefix on nitrogen means only ONE nitrogen. The prefix “mono” on oxygen indicates ONE oxygen. NO Is this not sooooooo easy!??

1. P4S5 2. N2O3 3. Na3N 4. Ni2S3 5. CuF2 6. CoS 7. CsI 8. Cl2O Reivew!!! 1. P4S5 2. N2O3 3. Na3N 4. Ni2S3 5. CuF2 6. CoS 7. CsI 8. Cl2O

-ic Acid Hydro- < NM > HCl HI H2S Prefix Suffix Hydro chlor ic Stem or root of nonmetal Prefix Suffix -ic Acid Hydro- < NM > HCl is a binary acid – hydrogen - nonmetal HCl Hydro chlor ic Acid HI Hydro iod ic Acid H2S Hydro sulfur ic Acid

Writing Formulas for Ionic Compounds List the symbol for each ion and its charge Ie. Al3+F- Find the least common multiple of the ion’s charges to make the compound neutral The least common multiple of 3 and 1 is 3 You only need 1 Al but 3 F Write out the formula with subscripts AlF3

Ionic Formulas- Criss-Cross Method Cross down the charge numbers and write the correct formulas for the following cations and anions. Let’s try it with Mg and Br  

You Try! Write out the formula and its name! Li, O K, Cl Br, Ba Li2O, Lithium Oxide KCl, Potassium Chloride BaBr2, Barium Bromide

FeBr3 More examples: Iron (III) bromide Fe+3 Br -1 Br -1 Br -1 Write the symbol and charge of each ion. The charge of the iron is provided by the Roman Numeral. Fe+3 Br -1 Br -1 Br -1 FeBr3 Balance the charges by supplying subscripts. The subscripts tell how many of each ion is needed to balance the compound. You’ll need three bromine ions to balance the one iron.

Al2S3 Aluminum Sulfide Al+3 S-2 S-2 Al+3 S-2 Write the symbol and charge of each ion. Balance the charges by supplying subscripts. Al+3 S-2 S-2 Al+3 In this case the charges do not evenly divide into each other. You must find the least common multiple. SIX S-2 Al2S3 How many aluminums are needed to arrive at a +6 charge? 2 How many sulfurs are needed to arrive at a -6 charge? 3

Formulas for Molecular Compounds Write the symbols for the first and second element Translate the prefixes into subscripts. Ie. Xenon Hexafluoride XF6 You aren't balancing charges of covalent compounds!

You Try! Write out the formula for each compound! Diarsenic pentoxide Tetraphosphorus trisulfide Tetraphosphorus decoxide Phosphorus trichloride As2O5 P4S3 P4O10 PCI3