In which scenario would an atom be least likely to form chemical bonds?
A The atom’s number of protons equals its number of electrons.
B The atom’s number of protons equals its number of neutrons.
C Its valence shell is full of electrons.
D There is only one electron in the valence shell.
The correct answer and explanation is:
The correct answer is C: Its valence shell is full of electrons.
Explanation:
Atoms tend to form chemical bonds in order to achieve a more stable electron configuration, usually by completing their outermost electron shell (valence shell). This stability is often achieved through chemical bonding, where atoms share or transfer electrons.
Option A: “The atom’s number of protons equals its number of electrons” refers to a neutral atom. While this is true for most atoms in their natural state, it does not directly determine whether the atom will form bonds. Even a neutral atom may form bonds if it has unpaired electrons in its valence shell or if it needs to achieve a stable electron configuration.
Option B: “The atom’s number of protons equals its number of neutrons” refers to the atom’s isotopic form. While isotopes of an element can have different numbers of neutrons, this does not generally affect the atom’s ability to form bonds. Chemical bonding depends more on the electron configuration than on the neutron number.
Option C: “Its valence shell is full of electrons” refers to the atom’s having a stable electron configuration, often the case for noble gases like helium, neon, and argon. These elements have a full valence shell, which makes them chemically inert, meaning they are least likely to form bonds with other atoms. Atoms with a full valence shell do not need to gain, lose, or share electrons, thus they have little to no tendency to bond.
Option D: “There is only one electron in the valence shell” refers to atoms like hydrogen and alkali metals (e.g., lithium, sodium), which have an electron in their outermost shell. These atoms are highly reactive because they tend to lose that one electron or share it in order to achieve a stable electron configuration. Therefore, atoms with one electron in their valence shell are likely to form chemical bonds.
In summary, an atom with a full valence shell is already in a stable, energetically favorable state and therefore least likely to form chemical bonds, as it does not need to gain, lose, or share electrons.