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Covalent Bonding. Molecule – two or more atoms covalently bound together Diatomic molecule —two of the same atom bound together. We begin with the molecule. These atoms never exist alone They always come in pairs Examples: Br Br 2 I I 2 NN 2 ClCl 2 HH 2 OO 2 FF 2.
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Molecule– two or more atoms covalently bound together Diatomic molecule—two of the same atom bound together We begin with the molecule
These atoms never exist alone • They always come in pairs • Examples: Br Br2 I I2 NN2 ClCl2 HH2 OO2 FF2 Diatomic Molecules
Two nonmetals share electrons so both have 8 valence electrons. Exception: H • Neither takes on a charge - no valence. • Do not crisscross to determine formula. • Must use prefixes in the name. • Name tells you the formula. Example: N2O4is dinitrogen tetroxide. • You cannot reduce the formulas!!! Covalent Compounds
Mon – 1 • Di – 2 • Tri – 3 • Tetra – 4 • Penta – 5 • Hexa – 6 • Hepta – 7 • Octa – 8 • Nona – 9 • Deca – 10 A prefix tells you the number of atoms of that element in the compound Covalent Prefixes
Find the 1st anion (nonmetal) and write down symbol • Look at the prefix and write it as a subscript after the symbol • Find the 2nd anion (nonmetal) and write down symbol • Look at the prefix and write it as a subscript after the symbol *NO CHARGES *NO REDUCING *If there is no prefix, then it only a 1don’t write 1’s Rules for Writing Covalent Compounds
Phosphorus trichloride • Nitrogen trihydride • Dinitrogen hexafluoride • Carbon tetrabromide • PCl3 • NH3 • N2F6 • CBr4 Examples: Write the Covalent Compound
1. Name the prefix for # of atoms in the 1st element -If the prefix is mono, drop it 2. Write the name for the 1st element 3. Name the prefix for the # of atoms in the 2nd element 4. Take the root name of the 2nd element and add “ide” Rules for Naming Covalent Compounds
N2O3 • CH4 • PO5 • S2F3 • Dinitrogen trioxide • Carbon tetrahydide • Phosphorus pentoxide • disulfurtrifluoride Examples: Name the Covalent Compound
Compounds that trap water crystals when they form • Both the name and the formula need to indicate how many water molecules are trapped • In the name we add the word hydrate with a prefix to express the number of water molecules • A dot is used in the formula to indicate “with” • Examples Calcium chloride dihydrate is CaCl2∙2H2O Chromium (III) nitrate hexahydrate is Cr(NO3)3∙6H2O Hydrates
Acids are compounds that contain one or more hydrogen atoms and produces H+ (hydrogen ions) when dissolved in water • The acid will consist of an anion combined with as many hydrogen ions as are needed to make the molecule electrically neutral. • If the formula has hydrogen written first, then it usually indicates that the hydrogen is an H+cation and the compound is an acid. Acids
Three Rules to Naming Acids • When the name of the anion ends in –ide, the acid name begins with the prefix hydro-. The stem on the anion has the suffix –icand is followed by the word acid Example:HCl(aq) is hydrochloric acid H2S(aq) is hydrosulfuris acid Naming Acids
2. When the anion name ends in –ite, the acid name is the stem of the anion with the suffix –ous, followed by the word acid Example: H2SO3 is sulfurous acid (SO3 is sulfite) Naming Acids
3. When the anion name ends in –ate, and the acid name is the stem of the anion with the suffix –icfollowed by the word acid Example: HNO3(aq) is nitricacid ((NO3) us nitrate ) Naming Acids
Use the rules for writing the names of the acids in reverse Example: Hydrobromic acid Rule #1 hydro- prefix and -icsuffix gives us a combination of the hydrogen ion ( H+ ) and the bromide ion or HBr Example: Phosphorous acid Refer to Rule #2, since we see the suffix –ous we know that is had to be an anion ending in –iteso we can look up phosphite (PO33-) and we need 3 H+ to neutralize so H3PO3 Writing Formulas for Acids
Example: Acetic acid Since we see the –icsuffix we will refer to rule #3 that tells us that the anion had to end in –ate so we look up the acetate ion (C2H3O2- ) and one hydrogen ion needed to neutralize which gives us HC2H3O2. Writing AcidsContinued…
H2SO3 • H2CO3 • HF • Nitrous acid • Perchloric acid • Iodic acid • Sulfurous acid • Carbonic acid • Hydrofluoric acid • HNO2 • HClO4 • HIO3 More examples:
Does the compound have a metal Yes No IONIC COVALENT (Metal cation + Nonmetal anion) (Two Nonmetals) Place metal first followed by nonmetal ending in –ide Place the nonmetal furthest Contain a Transition Metal? to the left on the periodic Yes No table first, then the other non- metal ending in –ide. Use Roman Do not use Numeral to tell Roman Numeral Use prefixes to tell the number of the valence of the Example atoms in the compound metal aluminum fluoride mono, di, tri, tetra, pent, hex Example Example iron(II)oxide dinitrogen trioxide Naming Compounds Flow Chart
KClO2 • CO2 • H2SO4 • NH4Br • CuCO3 • Fe2O3 • HClO • Potassium chlorite • Carbon dioxide • Sulfuric acid • Ammonium bromide • Copper (II) carbonate • Iron (III) oxide • Hypochlorousacid Mixed Examples
Carbon tetrachloride • Phosphorous pentachloride • Aluminum oxide • Copper (II) nitrate • Chlorous acid • Hydrophosphoric acid • Iron (III) hydroxide • CCl4 • PCl5 • Al2O3 • Cu(NO3)2 • HClO2 • H3P • Fe(OH)3 More Mixed Examples