Describe the trends in first ionization energy within groups and across periods in the periodic table. provide examples.

                   Within Groups: Ei decreases from top to bottom

                  Across Periods: Ei Increases from left to right

                           Ionization Energy is defined as, "the minimum amount of energy required to remove the valence electron from the valence shell of an atom in its gaseous state".

Trends in Periodic table:

               Across Periods:

                                        Ionization Energy increases from left to right along the periods because moving from left to right in the same period the number of protons (atomic number) increases but the number of shells remain constant hence, resulting in strong nuclear interactions and electrons are more attracted to nucleus hence, requires more energy to knock them out.

               Within Groups:

                                        Ionization energy decreases from top to bottom along the groups because the number of shells increases and the distance between nucleus and valence electrons also increases along with increase in shielding effect provided by core electrons. Therefore, the valence electrons experience less nuclear attraction and are easily removed.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.