How does bond order correspond to phase? use the drawing of mo energy diagram to predict the bond order of [be2]+ and [be2]−. determined that the bond order of [be2]+ is (+1/2).

Bond order is less in solid phases (usually 1), intermediate in liquid (2 or 3), and greatest in gases (3). [Be2]+ has a bond order of 1/2 and for [Be2]-, it has a bond order of 0. The bond order for [Be2]+ is calculated by:
(4 bonding e- - 3 nonbonding e-) / 2 = 1/2

Spontaneity tell us the direction of the reaction, but not how fast it goes. gibbs free energy brings together enthalpy, entropy and temperature in one easy formula. g = h - ts. and, finally the sign of delta g is always negative for a spontaneous reaction.