Chapter 2: Structure and Bonding
Topic 2.1: Ionic and Covalent Bonding
2.1.2 Valence Electrons and Symbols
-only valance electrons participate in bonding
-when drawing chemical structures it is only necessary to draw the valence electrons
-once a bond is created, any “memory” of where the electrons originated is lost
-electronegativity values often determine the types of bonds formed:
-Elements of low electronegativity typically form ionic bonds
-Elements of moderate electronegativity typically form covalent bonds
-Elements of higher electronegativity can form covalent or ionic bonds
2.1.3 What is Ionic Bonding?
-a bond is classified as ionic when the electronegativity difference is greater than 1.9
-ionic bond: assumed there is a complete transfer of an electron from the atom of lower
electronegativity to the atom with the higher electronegativity.
-transfer results in the formation of two ions that have electronic configurations corresponding
to noble gases
-the attractive Coulombic forces between the anions and cations result in the formation of crystal
-in a crystal lattice, a single cation is attracted too several anions and vice versa
-attractive forces in a crystal lattice are exceptionally strong and account for the very high melting points
of ionic compounds
-the magnitude of the attractive force between anions and cations is determined by Coulomb’s Law
2.1.4 What is Covalent Bonding?
-covalent bonds involve the sharing of electrons (sharing may or may not be equal)
-sharing deemed unequal if 0.5