Question

Many factors are responsible for the reactivity and chemical behavior of an atom. Which one is the most important factor ?

• A. The number of protons in the atom's nucleus
• B. The number of neutrons in the atom's nucleus
• C. The number of protons and neutrons in the atom's nucleus
• D. The ratio of protons to neutrons in the atom's nucleus
• E. The number of electrons in the atom's valence shell

Answer 1

Answer: (E)

The number of electrons in the atom's valence shell

The option (E) represents the most important factor. The number of electrons in the atom's valence shell are responsible for the reactivity and chemical behavior of an atom. For example, alkali metals and alkaline earth metals with 1 and 2 valence electrons readily loose valence electrons to form cations. On the other hands, halogens with 7 valence electrons gain one electron to form anion. Carbon with 4 valence electrons shares electrons to form covalent bonds.