Write the formula for Lithium Nitride. Agenda for Tuesday Jan 11th Review/Practice Ionic Bonds Metallic Bonds Covalent bonds

Rules for writing Ionic formulas The metal comes first (this does not include hydrogen), non-metal comes second. Find the oxidation number of each element The oxidation number of the metal becomes the subscript number of the non-metal and vise versa. Lithium nitride: Li1+ and N3- Li3N1 or Li3N

Rules for Naming Ionic formulas Write the name of the positive ion (metal). If you have a transition metal then you need to figure out its charge (remember the compound’s oxidation numbers must equal 0) and put it in roman numerals after the name; e.g. Copper (II). If it is not a transition metal proceed to step 3. Write the root of the non-metal’s name (chlor- for chlorine, ox- for oxygen). Add the ending –ide to the root.

Metallic Bonding Composed of closely packed cations Valence e- are a “sea of electrons” Attraction between valence e- and cations

Metallic Bonding “sea of electrons” model explains physical properties of metals Good conductors – e- flow freely Ductile malleable luster

Covalent Bonding Nonmetal + nonmetal share electrons Can share more than one pair (double, triple bond) Atoms held together by sharing electrons are covalently bonded

Covalent (Molecular) Bonds Properties Molecules Lower melting and boiling points Most are liq or gas Nonconductors Start to talk about shapes of molecules Ammonia molecule

Multiple Bonds Double and triple covalent bonds Sharing more than one pair of e- Carbon dioxide Nitrogen Triple bonds are stronger than double bonds More energy needed to break 3 bonds than 2 bonds

Polar and Nonpolar Covalent bonding can be: Polar – electrons not shared equally Nonpolar – electrons shared equally

Drawing Covalent Compounds Draw Dot structure for each compound Pair unpaired electrons of each compound Draw a line where you paired electrons

Prefixes Number of atoms Prefix 1 Mono 6 Hexa 2 Di 7 Hepta 3 Tri 8 Octa 4 Tetra 9 Nona 5 Penta 10 Deca

Naming Covalent Compounds 1st word: Give the prefix designating the number of atoms of the first element present, then write the element’s name. 2nd word: Give the prefix designating the number of atoms of the second element present. CO2: carbon di Name the root of the second element. CO2: carbon diox Add –ide to the root of the second element. CO2: carbon dioxide (official name)

Practice Dinitrogen Tetroxide N2O4 Phosphorus Pentachloride PCl5 CCl4 SCl2 Dinitrogen Tetroxide Phosphorus Pentachloride nitrogen monoxide or nitrogen oxide Carbon Tetrachloride Sulfur Dichloride 13

More Practice Sulfur Hexafluoride Pentanitrogen Heptoxide Diodine tetrachloride Triastatine Octoxide Phosphorous Mononitride SF6 N5O7 I2Cl4 At3O8 PN

Bonding 100% ionic 100% covalent polar covalent ionic and covalent NaCl NaNO3 Cl2 KBr Br2