Only valence electrons are shown in the Lewis structure held together by covalent bonds.
True
False
The correct answer and explanation is :
True
In a Lewis structure, only the valence electrons are shown because these are the electrons involved in chemical bonding. The core (or inner) electrons, which are found in the lower energy levels and are not involved in bonding, are not typically shown in the Lewis structure. Instead, the structure focuses on the arrangement of the atoms and the electrons that participate in the formation of covalent bonds, which are the valence electrons.
Explanation:
Lewis structures are diagrams used to represent the bonding between atoms in a molecule and the lone pairs of electrons that may exist on atoms. These structures help visualize how atoms share or transfer electrons to form bonds. Here’s why only valence electrons are shown in the Lewis structure:
- Valence Electrons: These are the electrons in the outermost shell (energy level) of an atom. For an atom to bond with others, it’s these electrons that interact, either by sharing in covalent bonds or transferring in ionic bonds. Therefore, the number of valence electrons dictates how many bonds an atom can form.
- Core Electrons: The electrons in the inner shells of an atom, also known as core electrons, are not involved in bonding. These electrons are tightly bound to the nucleus and do not participate in the formation of chemical bonds, so they are not depicted in the Lewis structure.
- Covalent Bonding: In covalent bonds, atoms share pairs of valence electrons to achieve more stable electron configurations, often resembling the noble gases. These shared electrons are shown in the Lewis structure as pairs or dashes between atoms. The lone pairs (pairs of electrons not involved in bonding) are shown as dots.
Thus, when drawing a Lewis structure, the focus is placed solely on the valence electrons, as they are the ones that interact to form bonds, which is why only these electrons are shown. This simplifies the representation of a molecule’s bonding and electronic structure.