2.58 for each element, give the following information:
[1] total number of electrons; [2] group number; [3] number
of valence electrons; [4] period; [5] number of the valence
shell.
a. oxygen b. sodium c. phosphorus

1. Oxygen

Total no of electrons 8

Group 6

No of valence electrons 6

Period 2

No of valence shell 2

2.Sodium

Total no of electrons 11

Group 1

No of valence electrons 1

Period 3

No of valence shell 3

3. Phosphorus

Total no of electrons 15

Group 5

No of valence electrons 5

Period 3

No of valence shell 3

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.