Ionic Bonding and Main-Group Elements. Chapter 6. ns 2 np 6. ns 1. ns 2 np 1. ns 2 np 2. ns 2 np 3. ns 2 np 4. ns 2 np 5. ns 2. d 10. d 1. d 5. 4f. 5f. Ground State Electron Configurations of the Elements. 8.2. Metals versus Nonmetals. Metals tend to form cations.
Ground State Electron Configurations of the Elements
Cations and Anions Of Representative Elements
Predict the charge of the following elements
Atoms lose electrons so that cation has a noble-gas outer electron configuration.
H- 1s2 or [He]
Atoms gain electrons so that anion has a noble-gas outer electron configuration.
F- 1s22s22p6 or [Ne]
O2- 1s22s22p6 or [Ne]
N3- 1s22s22p6 or [Ne]
F-: 1s22s22p6 or [Ne]
O2-: 1s22s22p6 or [Ne]
N3-: 1s22s22p6 or [Ne]
Na+, Al3+, F-, O2-, and N3- are all isoelectronic with Ne
same electron configuration as He
Predict the electronic structure of Mn2+ ?
When a cation is formed from an atom of a transition metal, electrons are always removed first from the ns orbital and then from the (n – 1)d orbitals.
Mn2+: [Ar]4s03d5 or [Ar]3d5
Cation is always smaller than atom from which it is formed.
Anion is always larger than atom from which it is formed.
Size of Ions
Ionization energy is the minimum energy (kJ/mol) required to remove an electron from a gaseous atom in its ground state.
Ei1 + X(g) X+(g) + e-
Ei1 first ionization energy
Ei2 + X+(g) X2(g) + e-
Ei2 second ionization energy
Ei3 + X2+(g) X3+ +e-
Ei3 third ionization energy
Ei1 < Ei2 < Ei3
X (g) + e- X-(g)
F (g) + e- X-(g)
O (g) + e- O-(g)
ΔH < 0
DH = -328 kJ/mol
DH = -141 kJ/mol
Sodium Chloride (NaCl):
Born–Haber Cycle for NaCl:
Born–Haber Cycle for MgCl2:
DHoverall = DH1 + DH2 + DH3 + DH4 + DH5
Born-Haber Cycle for Determining Lattice Energy
Sum = 562 kJ/mol
K(s) + ½ F2(g) KF(s) ΔH = -562 kJ/mole
Electrolysis formation of KF(s) from the elements is the process in which electrical energy is used to cause a nonspontaneous chemical reaction to occur.
450°C in KCl formation of KF(s) from the elements
580°C in CaCl2
3Cl2 + 2MnO2 + 4H2O + 2K+