Below is the Lewis structure of the chloroform (
) molecule. H :Cl:C:Cl: :Cl: Count the number of bonding pairs and the number of lone pairs around the bottom chlorine atom. bonding pairs: lone pairs:
The Correct Answer and Explanation is:1
Answer:
- Bonding pairs: 1
- Lone pairs: 3
Explanation
Chloroform, with the chemical formula CHCl₃, consists of one carbon atom bonded to one hydrogen atom and three chlorine atoms. Let’s analyze the bonding and electron arrangement specifically around the bottom chlorine atom in its Lewis structure.
A Lewis structure shows how atoms are connected using bonding pairs (shared electrons between atoms forming covalent bonds) and lone pairs (non-bonding electrons localized on a single atom). Chlorine (Cl), which has 7 valence electrons (since it’s in Group 17 of the periodic table), tends to form one single covalent bond to complete its octet (8 electrons in total).
In CHCl₃, each chlorine atom forms a single covalent bond with the central carbon atom, contributing 1 bonding pair (2 electrons shared between Cl and C). After forming this bond, the chlorine atom still has 6 remaining valence electrons, which it keeps as 3 lone pairs (6 electrons total).
So, for the bottom chlorine atom:
- 1 bonding pair: shared with carbon.
- 3 lone pairs: non-bonding electrons.
To double-check:
- Chlorine starts with 7 valence electrons.
- It shares 1 electron with carbon (1 bonding pair = 2 electrons, 1 from Cl and 1 from C).
- That leaves it with 6 electrons as lone pairs.
- 6 electrons = 3 lone pairs.
This satisfies the octet rule (1 bond = 2 electrons + 6 electrons from lone pairs = 8 electrons total around Cl).
This is the same for all three chlorine atoms in chloroform, but since the question asks only about the bottom chlorine, the answer remains:
- Bonding pairs: 1
- Lone pairs: 3
This understanding is fundamental in predicting molecular geometry, reactivity, and polarity.
