2BondingBonding between atoms in a compound comes from the sharing of electronsThe kind of bond formed between the two atoms depends on the amount of sharing of the electrons
3Bonding in CompoundsKinds of BondsIonicelectron transferred from one atom to anothergenerally between a metal cation and a non metal anionCovalentelectrons shared between 2 atoms in a bond
4Electronegativity Li Be B C N O F 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Measure of the ability of an atom in a bond to attract the bonding electronsAcross a Period: EN increasesDown a Group: EN decreasesMost electronegative element is fluorineLi Be B C N O FNa Mg Al Si P S ClK Ca Ga Ge As Se Br
5Determine the amount of covalent or ionic character in a bond Using Electronegativity The difference in electronegativity between two atoms can be used to determine how ionic or how covalent the bond is
6Difference in electronegativity EN = 1.7 = 50% ionicEN > 1.7 more ionicEN < 1.7 more covalentThe larger the EN, the more ionic the bondThe smaller the EN, the more covalent the bondSo the farther apart the atoms are the more ionic the bond
7Compare three bonds:A) C--F B) O--F C) N--FWhich is the most ionic?
8Compare three bonds:A) C--F B) O--F C) N--FWhich is the most covalent?
9Determine the amount of covalent or ionic character in a bond Fajan’s Rules of CovalencyThe bond with the smaller cation is the more covalent bondThe bond with the larger anion is the more covalent bondThe bond with the larger charge on the cation or anion is the more covalent bondThe bond with a transition metal cation is the more covalent bond
10Predict which is the more covalent SbCl3 BiCl3 BeO BeS Tl2O Tl2O3 NaCl CuClSb is smaller than Bi, so the SbCl3 ismore covalentS is larger than O, so the BeS ismore covalentCompare Tl+ and Tl+3 , thallium(III) oxidemore covalentCu is a transition metal, CuClmore covalent
11Which is the Most Covalent? MgCl2MgBr2CaCl2CaBr2
12Which is the Most Covalent? MgCl2 MgBr2 CaCl2 CaBr2 Compare: Mg cation and Ca cation.Mg smaller than Ca so Mg compoundsmore covalentCompare: Cl anion and Br anion.Br larger than Cl, so Br compoundsmore covalent
14Which is the Most Ionic? MgCl2 MgBr2 CaCl2 CaBr2 Most ionic is the same asleast covalentCompare: Mg cation and Ca cation.Mg smaller than Ca so Mg compoundsmore covalent, Ca more ionicCompare: Cl anion and Br anion.Br larger than Cl, so Br compoundsmore covalent, Cl more ionic
15Which of the following is least covalent? Cu2OCuOCu2SCuS
16Which of the following is least covalent? Cu2O CuO Cu2S CuS Compare anions O and S. S is the larger anion, so itforms more covalent bonds. Therefore, Cu2O andCuO are less covalentCu2O is Cu+1, CuO is Cu+2 , the larger charge is morecovalent, so Cu2O is the least covalent
17Which of the following is least ionic? AgClNaClAuClRbCl
18Which of the following is least ionic? AgCl NaCl AuCl RbCl Least ionic is Most covalentAg and Au are transition metals, so theyare more covalent than Na and Rbwhich are Group 1 Alkali metals.Compare Ag and Au. Ag is the smallersize so it forms the most covalent bond.
19Bond polarityBecause electrons are shared unequally in a bond due to the difference in electronegativity, a covalent bond has a positive end and a negative end. (poles)The bond is said to be polarH ---ClBond dipole - occurs when you have a polar bondDipole moment () - is a measure of the bond dipole (the amount of polarity)-+
20Bond Polarity The more ionic the bond the more polar the bond The more ionic the bond, the larger the bond dipoleThe more ionic the bond, the greater the dipole moment.
21Compare three bonds:A) C--F B) O--F C) N--FWhich is the least polar bond?