5) Which element has the lowest first ionization energy?*
Li
K
Na

K

Explanation:

Ionisation energy is the energy required for electron loss and the higher the occupied energy levels=higher atomic radius=the lower the ionisation energy thus k=2.8.8.1

Na=2.8.1

Li=2.1

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

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.