+ Naming and Formula Writing
+ Chemical Formulas Shows the kind and number of atoms in the smallest piece of a substance Use subscripts to show the number of atoms per element Molecular formula- number and kinds of atoms in a covalent molecule CO 2 C 6 H 12 O 6 Smallest ratio of atoms in an Ionic Compound is the Formula Unit NaCl BaCl 2
+ Laws of Chemical Formulae Law of Definite Proportions- In a sample of a chemical compound, the masses of the elements are always in the same proportions H 2 O (water) and H 2 O 2 (Hydrogen peroxide) Law of Multiple Proportions- atoms can combine in multiple ratios to form different compounds with different properties (Dalton) H 2 O is different than H 2 O 2 CO is a poisonous gas, CO 2 is not
+ Categories of Chemical Naming Ionic Compounds Combinations of metal and nonmetal ions Binary- 2 ions Ternary-3 ions, and polyatomic ions Covalent Molecules: Combinations of nonmetals Acids Simple binary acids Oxyacids Organic Chemistry
+ Remember Ionic Compounds Ionic Compounds- from joining metal cations and nonmetal anions Electrically neutral Cation and anion surround each other in a crystal lattice structure Smallest ratio of atoms is the formula unit Melt at high temperatures
+ Naming Ionic Compounds First, name the metal, or cation: Positive ions are formed by losing e- There is no name change for the positive ions Name is the same as the metal atom K + potassium Ca 2+ calcium
+ Naming Ionic Compounds Transition metals can have more than one type of charge In the stock system, indicate the charge with roman numerals in parenthesis Cu + Copper (I) Cu +2 Copper (II) Fe +2 Iron (II) Fe +3 Iron (III) Sn +2 Tin (II) Sn +4 Tin (IV)
+ Other Transition Metals with Multiple Charges
+ Naming Ionic Compounds Transition Metals and the Classical System: The suffix ous is used to indicate the lower valence, or lower positive charge The suffix ic is used to name the metal with the higher valence electrons, or higher positive charge
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+ Transition Metal Exceptions Some of the transition metals have only one ionic charge Do NOT use roman numerals for these: Aluminum is always +3 Zinc is always +2 Silver is always +1
+ Naming Ionic compounds Second, name the nonmetal, or anion: Negative ion formed by a nonmetal atom gaining electrons For these anions, drop the ending of the atom s name, and add ide F - Fluoride O 2- Oxide Cl - Chloride N 3- Nitride
+ What are ternary ionic compounds? Ternary Ionic Compounds have three different elements These compounds have POLYATOMIC IONS Polyatomic ions are groups of elements, with a single charge, that behave as one element in an ionic compound
+ Converting formula to name: binary edition KCl BaS Al 2 O 3 Na 3 N Fe 2 O 3 Sc 3 P 2
+ What are ternary ionic compounds? Ternary Ionic Compounds have three different elements These compounds have POLYATOMIC IONS Polyatomic ions are groups of elements with a single charge that behave as one element in an ionic compound
+ Converting Formula to Name: Ternary edition Na 2 CO 3 FeSO 3 CaSO 4 NH 4 OH K 3 PO 4 LiCn
+ Names from Formulas The Criss-Cross Method Returns Write the formula for Aluminum Oxide Al 3+ + O 2- Al 2 O 3 Write the formula for Copper (II) Hydroxide Cu 2+ + OH -
+ Converting Name to Formula Tin (IV) Carbonate Copper (I) cyanide Aluminum Fluoride Sodium Hydroxide Lithium Nitrite Calcium Phosphate
+ Covalent In ionic compounds, the number of atoms is easily determined from the name and expected charge of the ions Covalent molecules are held together by sharing of electrons, and not balanced ionic charge Name has to include more information
+ Covalent Molecules Made from only nonmetals Can be from one element O 2, N 2, H 2, F 2, Cl 2, Br 2, & I 2 The molecule s name is simply the name of the element Can be made of 2 or more nonmetals CO 2, N 2 O, H 2 O The name has to detail exactly how many of each
+ Covalent Molecules Covalent compounds use prefixes Mono- 1 Di- 2 Tri- 3 Tetra- 4 Penta- 5 Hexa- 6 Hepta- 7 Octa- 8 Otherwise, left right nomenclature of ionic compounds is used. Mono is left off for first atom; NO 2 nitrogen dioxide No double vowels when writing names (oa, oo) tetroxide
+ Covalent Molecules CO CO 2 H 2 O P 2 O 3 CCl 4 SF 6
+ Names from Formulas Diphosphorus pentoxide Tetraiodine nonoxide Silicon hexafluoride Nitrogen trioxide Carbon tetrahydride Phosphorus trifluoride
+ Naming and writing Formulas for acids What is an acid? Compounds that give off H+ ions when dissolved in water Must have H+ in them Will always be some H next to an anion The anion determines the name
+ Naming simple binary acids If the anion attached to hydrogen ends in ide, put the prefix hydro- and change ide to ic acid HCl- hydrogen ion and chloride ion Hydrochloric acid H 2 S hydrogen ion and sulfide ion Hydrosulfuric acid
+ Naming Oxyacids If the anion has oxygen in it, the polyatomic ion s name ends in ate or ite Change the suffix ate to ic acid (no prefix) HNO 3 Hydrogen and nitrate ions Nitric Acid Change the suffix ite to ous acid HNO 2 Hydrogen and nitrite ions
+ Writing Acid Formulas Hydrogen will always be first Name will tell you the anion Make the charges cancel Starts with Hydro if no oxygen, -ide No hydro? ate comes from ic, -ite comes from ous SO 4 2- is sulfate: H 2 SO 4 is Sulfuric Acid SO 3 2- is sulfite; H 2 SO 3 is Sulfurous Acid
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