CHAPTER 5 NAMING COMPOUNDS

Transcription

1 UNDERSTANDING CHEMICAL FORMULAS CHAPTER 5 NAMING COMPOUNDS General information The formula tells the elements that make up a compound and the number of atoms of each element in the compound. -when a subscript is written outside of a set of parentheses, there are multiples of those groups Example FeCl2 There is 1 iron atom for every 2 chlorine atoms Mg3(PO4)2 There are 3 total magnesium atoms for every 2 GROUPS of PO4 compounds Practice BeF there are beryllium atoms for every fluorine atoms Cu2(CrO4)3 there are copper atoms for every chromate compounds DETERMINING BOND TYPE- A. Ionic bonds- bonds between a metal and a nonmetal ex NaCl B. Covalent bonds- bonds between two nonmetals - ex H2O C. Metallic bonds-bonds between two atoms of same metal- ex Cu D. Practice 1. Mg and F 2. Na and Br 7. H and H 3. O and Cl 4. Fe and Fe 8. H and Cl 5. Zn and Zn 6. O and F 1

2 NAMING IONIC FORMULAS What does an ionic compound look like????? It is a compound with a bond between a metal and a non-metal What are the rules for naming ionic compounds?? (with no transition metals) Binary Ionic Compounds (metals from Group 1 or 2) (ex: CaCl2) 1. Name the metal 2. Name the nonmetala. change ending to ide 3. CaCl2 = calcium chloride EXAMPLE a. KCl potassium chloride b. LiF lithium fluoride c. Na2O sodium oxide Ionic Practice (no transition metals) CaO MgF2 NaCl RbBr Writing Ionic Formulas (with no transition metal) Criss-cross the charges (oxidation numbers) Na + Cl = Magnesium fluoride = + = Calcium oxide = + = N + Li = **why is lithium written before nitrogen? The cation is always written first 2

3 What are the rules for naming ionic compounds?? (with transition metals) *Transition metals work a differently because they vary their valence electrons. Figure out oxidation number of transition metals by looking at what they are paired with *We use roman numerals to do this: I = one II = two III = three IV = four Transitions metals Binary Ionic Compounds (transition metals) (ex: Fe2O3) 1. Name the metal 2. Transition metals have more than one + charge (ex:iron can have +2 or +3) a. determine the charge of nonmetal ***helpful hint the TOTAL charge must always = 0 Fe O EXAMPLES NiS FeF3 AgCl Practice Cr (+4) + O b. Figure out the total - charge on non-metal side, then set the total metal equal to the + charge 3. After the name of metal, write charge in roman numerals. {put in ( )} Fe +3 = iron (III) 4. Name the nonmetal. Change ending to ide 5. Fe2O3 = Iron(III)oxide Nickel (II) sulfide Iron (III) fluoride Silver (I) chloride = Fe2O3 = ZnCl2 = CuO = MnO2 = 3

4 Writing Ionic Formulas (with transition metals) Figure out the symbols and criss cross the charges Zinc (II) fluoride + = Nickle (I) acetate + = Gold (III) cyanide + = Copper (II) nitrite + = NAMING COVALENT COMPOUNDS What does a covalent compound look like??? It is a compound with a bond between a nonmetal and a nonmetal What are the rules for naming covalent compounds??? Use prefixes to name covalent compounds, change ending of second compound to ide 1. Use same ending as most ionic compounds.ide 1. Covalent Bonding requires Prefixes a. prefixes tell you how many of each atom there are in the compound b. you cannot start any covalent compound with the word mono PREFIX NUMBER Mono 1 Di 2 Tri 3 Tetra 4 Penta 5 Hexa 6 Hepta 7 Octa 8 Nona 9 Deca 10 Examples N2O4 Dinitrogen tetraoxide H2O Dihydrogen monoxide BF3 Boron trifluoride **notice no mono to start name!! 4

5 Covalent Practice SiO2 CO2 CO P2O5 Writing Covalent Formulas No criss cross - write exactly as written Trichlorine pentaoxide Nitrogen octahydride 5

6 NAMING COMPOUNDS WITH POLYATOMICS Poly = many General Information Polyatomic ions are made of covalently bonded atoms that tend to stay together and act as if they were single atoms a. therefore bonds WITHIN polyatomic ions = covalent b. but they usually form ionic bonds with other atoms What does a polyatomic look like? Since we are only naming binary compounds, any compound that has more than 2 capital letters has a polyatomic in it & almost all polyatomics end with something other then IDE Some of the common polyatomics and their charge Ammonium NH4 +1 Acetate C2H3O2-1 Chlorate ClO3-1 Hydrogen carbonate HCO3-1 Hydroxide OH -1 Nitrite NO2-1 Nitrate NO3-1 Carbonate CO3-2 Sulfate SO4-2 Sulfite SO3-2 Phosphate PO4-3 Rules for naming compounds with polyatomic ions Follow the previous rules for naming IONIC compounds (with and without transition metals) BUT do not change the polyatomic ending EXAMPLE Mg(OH)2 CuSO4 Zn(NO3)2 K2CO3 magnesium hydroxide copper (II) sulfate Zinc (II) nitrate potassium carbonate 6

7 Practice Na2CO3 Ca(ClO3)2 Ca(OH)2 K3PO3 MnSO3 Writing formulas for compounds with polyatomics Figure out the symbols and criss cross the charges Lead (II) hydroxide + = Beryllium phosphate + = Copper (II) carbonate + = Silver (I) permanganate + = 7

8 NAMING ACIDS General information on acids -When dissolved in water, certain molecules produce H + ions. These substances are called acids. -An acid can be viewed as a molecule with one or more H + ions attached to an anion (negatively charged atom). What does an acid compound look like???? Look for a compound that has the H atom first and is connected to something else (an anion) Rules for naming acids #1 Does the acid contain an oxygen in the formula???? a. If the anion DOES NOT CONTAIN OXYGEN, the acid is named with the prefix hydro and the suffix ic is attached to the root name for the element EXAMPLE HCl dissolved in water = no oxygen therefore.hydrochloric acid HCN disssolved in water = hydrocyanic acid H2S dissolved in water = hydrosulfuric acid b. If the anion DOES CONTAIN OXYGEN, the acid name is formed from the root name of the central element of the anion with a suffix of ic or ous. i. When the anion name ends in ate the suffix ic is used. ii. When the anion name ends in ite the suffix ous is used EXAMPLE (for anions with ate ending) H2SO4 dissolved in water = the anion is sulfate so.sulfuric acid H3PO4 dissolved in water = the anion is phosphate so. phosphoric acid HC2H3O4 = anion is acetate so acetic acid EXAMPLE: H2SO3 = anion is sulfite so.. sulfurous acid HNO2 = anion is nitrite so. Nitrous acid 8

9 ACID PRACTICE: H3PO4 H3PO3 HF HCl Writing acid formulas Do this process in reverse and criss-cross the charges (oxidation numbers) Hydrochloric Acid H + Cl = Sulfurous Acid H + = Phosphoric Acid H + = 9