Chemical Names and Formulas

Ions consisting of a single atom with a + or - charge Monatomic Ions Ions consisting of a single atom with a + or - charge Anions (-) Most from 5A, 6A, 7A Naming: Start with the stem of the element’s name ending with -ide Example: Fluoride, Chloride, Nitride Cations (+) Most from Groups 1A, 2A, 3A Naming: Same as the name of the metal, followed by ion or cation Example: Sodium Ion, Potassium Ion Naming Ions

Naming halogen compounds When combined with other elements in simple compounds the name of the halogen element changes slightly from ...ine to ...ide. Fluorine forms a fluoride (ion F-), chlorine forms a chloride (ion Cl-), bromine a bromide (ion Br-) and iodine an iodide (ion I-). Naming halogen compounds

The other element at the start of the compound name e. g The other element at the start of the compound name e.g. hydrogen, sodium, potassium, magnesium, calcium, etc. remains unchanged. So typical halogen compound names are,  potassium fluoride, hydrogen chloride, sodium chloride, calcium bromide, magnesium iodide etc. The elements all exist as X2 or X-X, diatomic molecules where X represents the halogen atom.

Naming Ions Transition Metals *Charges must be determined by the number of electrons lost *Can have varying charges for the same elements *Naming: Two Methods Stock System: Roman numerals in parentheses Example: Fe2+ Written: Iron(II) ion Read: “Iron two ion,” Example: Fe3+ Written: Iron(III) ion Read: “iron three ion”

Naming Ions Transition Metals Classical System: suffix used with root name to name the ion Example: Fe2+ Written: Ferrous Ion Example: Fe3+ Written: Ferric Ion Example: Cr2+ Written: Chromous Ion Example: Cr3+ Written: Chromic Ion

Naming Ions Transition Metals -Classical System: some names may seem unfamiliar -Iron: Ferr- -Copper: Cupr- -Tin: Stann- -Lead: Plumb- -Some transition metals have only one charge Ag+ Cd2+ Zn2+

Naming Ions Polyatomic Ions Ions composed of more than one atom Tightly bound groups of atoms that behave as one unit and have a charge All Anions ending in -ite or -ate contain Oxygen “-ites” have one less oxygen than “-ates” Examples: ClO2- Chlorite ClO3- Chlorate Cr2O72- Dichromate PO33- Phosphite

Naming Ions Polyatomic Ions When a polyatomic ion contain Hydrogen, it is like adding a H+ with another polyatomic ion Examples: H+ + CO32- ----> HCO3- Carbonate Hydrogen Carbonate H+ + PO43- ----> HPO42- Phosphate Hydrogen Phosphate

Based on “opposites attract” Ionic Bonds Bonds between ions Based on “opposites attract” Cation + Anion (+) charge (-) charge (metals) (nonmetals)

Naming Chemical name + Chemical name of cation of anion PLUS “ide” ending Example: Na+ + Cl- NaCl Sodium chloride (capitalized) (not capitalized)

Unlike atoms, compounds are stable when they are neutral There is no way to know from the name how many atoms of each kind are present in an ionic compound Therefore, the chemical formula is needed to determine the number of each atom necessary for a reaction to occur

Chemical Name Sodium chloride Swap charges Na1+ + Cl1- superscript = charge on ion Na1 + Cl1 subscript = number of atoms needed to form the compound Chemical Formula NaCl

Naming and Writing Formulas Binary Ionic Compounds An ionic or molecular compound composed of two elements Antoine-Laurent Lavoisier developed a naming system w/ other chemists Naming: Place the cation first followed by the anion. Formula: Cation first, Anion second Remember, total charge equals zero! Example: Cs2O = Cesium Oxide (Ionic) CuO = Copper(II) Oxide (Ionic) Hint: 1:1 ratio

Naming and Writing Formulas Binary Ionic Compounds

Naming and Writing Formulas Compounds with Polyatomic Ions Recall that a Polyatomic Ion acts as one unit Naming: Place the cation first followed by the anion. Formula: Cation first, Anion second Example: PbSO4 = Lead(II) Sulfate K2HPO4 = Potassium Hydrogen Phosphate

Naming and Writing Formulas Compounds with Polyatomic Ions

Naming and Writing Formulas Naming Binary Molecular Compounds The prefix tells how many atoms of each element are present in each molecule of the compound Carbon Monoxide vs. Carbon Dioxide Mono- indicates one oxygen Di- indicates two oxygens

Naming and Writing Formulas Guidelines for Naming Confirm the compound is a molecular compound (2 nonmetals) Omit mono- when the the formula contains only one of the first element in the name Add -ide to the second element in the formula Guidelines for Formula Writing 1) Use the prefixes in the name to tell you the subscripts in the formula

Naming and Writing Formulas Practice Write the name of these molecular compounds: NCl3 BCl3 NI3 SO3 N2H4 N2O3

Naming and Writing Formulas Practice Write the formulas for these binary molecular compounds: Phosphorus pentachloride Iodine heptafluoride Chlorine trifluoride Iodine dioxide Carbon tetrabromide Diphosphorus trioxide

Naming and Writing Formulas Acids A compound that contains one or more hydrogen atoms and produces hydrogen ions (H+) when dissolved in water Acids consist of an anion and as many H+ as are necessary to make the atom electrically neutral. HnX

Naming and Writing Formulas Naming Acids When the anion’s name ends in -ide, the acid’s name begins with hydro- and the stem of the anion’s name ends in -ic, followed by the word acid. Example: Hydrochloric Acid HCl Anion: Chloride Cl-

Naming and Writing Formulas Naming Acids 2) When the anion’s name ends in -ite, the acid’s name is the stem of the anion with the suffix -ous, followed by the word acid. Example: Sulfurous Acid H2SO3 Anion: Sulfite SO32-

Naming and Writing Formulas Naming Acids 3) When the anion’s name ends in -ate, the acid’s name is the stem of the anion with the suffix -ic, followed by the word acid. Example: Nitric Acid HNO3 Anion: Nitrate NO3-

Naming and Writing Formulas Writing Formulas for Acids Use the rules for naming acids in reverse to write formulas for acids. Find the anion in the acid. Then, match its charge with the appropriate number of H+ ions to make the formula electrically neutral.

Naming and Writing Formulas Names and Formulas for Bases An ionic compound that produces hydroxide ions (OH-) when dissolved in water. These are named in the same way as other ionic compounds: cation first and anion second. Common Bases NaOH Sodium Hydroxide Ba(OH)2 Barium Hydroxide Ca(OH)2 Calcium Hydroxide

The Laws Governing Formulas and Names The Laws of Definite Proportions In samples of any compound, the masses of the elements are always in the same proportions Example: 100 g of MgS has 43.13 g of Mg and 56.87 g of S Ratio: 0.758/1

The Laws Governing Formulas and Names The Laws of Multiple Proportions Whenever the same two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers Example: 16 g of O in H2O2 to every 1 g of H = 2:1 8 g of O in H2O to every 1 g of H

The Laws Governing Formulas and Names The Laws of Multiple Proportions Carbon and Oxygen can form two compounds. A: contains 2.41 g of C for every 3.22 g of O B: contains 6.71 g of C for every 17.9 g of O A: 2.41 g of C/3.22 g of O = 0.748 g C/g O B: 6.71 g of C/17.9 g of O = 0.375 g C/ g O 0.748 g/0.375 g = 1.99/1 = about 2:1

The Laws Governing Formulas and Names The Laws of Multiple Proportions

Naming Chemical Compounds

The Laws Governing Formulas and Names Naming Chemical Compounds Guidelines: -ide generally indicates a binary compound -ite or -ate means a polyatomic ion that includes O Prefixes generally indicate a molecular compound A Roman numeral shows the charge of the cation