Chemical Bonding & Nomenclature Objectives: Distinguish between covalent and ionic bonding Explain the process of bonding Name ionic and covalent compounds and acids Write chemical formulas for ionic and covalent compounds and acids Ionic Bonds formed between a cation & an anion involve transfer of electrons form ionic compounds Nov 26 9:46 AM Nov 26 9:53 AM Ionic Compounds: can be binary (two elements) can contain one or more polyatomic ions overall electric charge of the compound is zero held together by ionic bonds Polyatomic Ions: groups of atoms that act together as a single unit You need to memorize formulas and charges for several common polyatomic ions! (Handout) Nov 26 9:55 AM Nov 26 9:57 AM Chemical Formulas: uses chemical symbols & subscript #'s indicate the types and #'s of atoms/ions in the compound positively charged ions come first negatively charged ions are written last Example: K 2 S formula for potassium sulfide Binary Ionic Compounds: Determine the formula for the compound that forms between: Sodium and Chlorine Nov 26 10:03 AM Nov 26 10:00 AM
magnesium and chlorine aluminum and sulfur calcium and oxygen phosphorus and barium Nov 26 10:01 AM Nov 26 10:01 AM Follow the same procedure to determine formulas of ionic compounds that contain polyatomic ions. * Remember to include parenthesis if you have more than one polyatomic ion in the formula! Example: Calcium hydroxide Example: Sodium + Nitrate Nov 26 10:06 AM Nov 26 10:08 AM Remember that roman numerals indicate charge for transition metals and tin & lead. (Except: Zn 2+, Ag +, & Cd 2+ ) Example: Copper (II) sulfide Practice These: 1. sodium oxide 2. magnesium carbonate 3. iron (II) fluoride 4. strontium nitrate 5. zinc phosphate Nov 26 10:10 AM Nov 26 10:09 AM
Naming Ionic Compounds: 1. Name the cation. Remember to include Roman numerals when appropriate. 2. Name the anion. Remember that anions formed from single elements have the ending ide. **NEVER change the name of a polyatomic ion!** Examples: 1. CaO 2. Na 3 PO 4 3. PbS 4. Cu 2 O 5. Fe 3 (PO 4 ) 2 Nov 26 10:12 AM Nov 26 10:14 AM Practice for you: 1. Ag 2 O 2. Fe 2 S 3 3. Mn(OH) 2 4. Na 2 CO 3 5. CaSO 4 Covalent Bonds electrons are shared can be polar (unequal sharing) or nonpolar (equal sharing) Polarity depends on electronegativities of the bonding atoms typically forms between 2 nonmetal atoms can be single, double, or triple Nov 26 10:15 AM Nov 26 10:17 AM Molecular (Covalent) Compounds: held together by covalent bonds usually only contain nonmetals can be arranged in different ratios depending on the types of bonds Example: Carbon dioxide vs. Carbon monoxide Naming Binary Molecular (Covalent) Compounds: Prefixes indicate the # of each atom present. 1 = mono 6 = hexa 2 = di 3 = tri 4 = tetra 5 = penta 7 = hepta 8 = octa 9 = nona 10 = deca Nov 26 10:21 AM Nov 26 10:23 AM
Format is: prefix + name prefix + name ide You try these: Example: dinitrogen pentaphosphide 1. CO 2 2. CH 4 3. Si 2 O 4 4. SF 4 EXCEPTION: mono is not used if there is only one of the first element. 5. ICl 5 Nov 26 10:26 AM Nov 26 10:28 AM Name these: 1. N 2 O 2. NO 2 3. Cl 2 O 7 4. CBr 4 5. BaCl 2 ACIDS: Compounds that give off hydrogen ions (H 1+ ) when dissolved in water (the Arrhenius definition) Will start the formula with H. There will always be some Hydrogen next to an anion. The anion determines the name. Nov 26 10:30 AM Nov 26 10:32 AM Rules for Naming acids: Name it as a normal compound first 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 Acids If the anion has oxygen in it, then it ends in ate or ite change the suffix ate to ic acid (use no prefix) > Example: HNO 3 Hydrogen and nitrate ions = Nitric acid change the suffix ite to ous acid (use no prefix) > Example: HNO 2 Hydrogen and nitrite ions = Nitrous acid Nov 26 10:33 AM Nov 26 10:34 AM
Naming Acids Practice by naming these: 1. HF 2. H 3 P 3. H 2 SO 4 4. H 2 SO 3 5. HCN 6. H 2 CrO 4 Nov 26 10:35 AM Nov 26 10:37 AM Writing Acid Formulas in reverse! Hydrogen will be listed first The name will tell you the anion Be sure the charges cancel out. Starts with prefix hydro? there is no oxygen, ide ending for anion no prefix hydro? > ate anion comes from ic ending > ite anion comes from ous ending Write formulas for these: 1. hydroiodic acid 2. acetic acid 3. carbonic acid 4. phosphorous acid 5. hydrobromic acid Nov 26 10:38 AM Nov 26 10:39 AM Nov 26 10:40 AM