What do you mean by atomic number?

Atomic number is the number of protons in an isotope or element.

Explanation: The atomic number is the same number of protons in an element or isotope and if said isotope is neutral than it is the same number of electrons.

Example: Atomic number = 19 Protons = 19 if neutral Electrons = 19

hi my dude or dudette

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.