Question

The number of lone pairs of electrons present in central atom of \(\mathrm{ClF}_{3}\) is: (a) 0 (b) \(]\) (c) 2 (d) 3

Short answer

2 lone pairs are present on the central chlorine atom in \\(ClF_{3}\\).

Step-by-step solution

Determine the Valence Electrons on Chlorine

First, we need to determine the number of valence electrons in the central atom, which is chlorine (Cl). Chlorine belongs to group 17 of the periodic table and has 7 valence electrons.

Calculate Total Electrons in \\(molecule\\u00bfClF3\\u00bf\\u00bf

The formula \(ClF_{3}\) means that chlorine is bonded to three fluorine atoms. Each fluorine atom provides 1 electron to the bond, so there are 3 \(F\) atoms contributing a total of 3 electrons.

Count Bonding Electrons

Chlorine uses 3 of its valence electrons to form bonds with the 3 fluorine atoms. 1 electron is used for each \(Cl-F\) bond, totaling 3 bonding electrons.

Determine Lone Pairs

Since chlorine initially had 7 electrons, after forming bonds with the 3 \(F\) atoms, it uses 3 electrons, leaving \(7 - 3 = 4\) electrons. These remaining 4 electrons (2 pairs) are the lone pairs on the central chlorine atom.

Key concepts

Lone Pairs in Molecules

Lone pairs in molecules are pairs of electrons that do not engage in bonding. They belong exclusively to one atom. In the case of \( \mathrm{ClF}_3 \), we are interested in the lone pairs on the central atom, chlorine. Counting lone pairs is crucial for determining the shape and properties of molecules, especially when using models like the VSEPR theory.

For \( \mathrm{ClF}_3 \), chlorine initially has 7 valence electrons. Once it bonds with the three fluorine atoms, which each require one electron, some electrons are left unshared. These unshared electrons remain as lone pairs on the chlorine. After bonding, chlorine uses 3 of its electrons, leaving 4 electrons or 2 pairs as lone pairs. Lone pairs influence how the atom arranges itself spatially, impacting the overall geometry of the molecule.

Valence Electrons

Valence electrons are the outermost electrons of an atom and play a key role in bonding. They are the electrons that participate in the formation of chemical bonds.

For an atom like chlorine in \( \mathrm{ClF}_3 \), it has 7 valence electrons because it is in group 17 of the periodic table. Valence electrons determine an element's chemical properties and its ability to form bonds with other atoms. Each bond involves sharing or transferring valence electrons between atoms. In \( \mathrm{ClF}_3 \), chlorine shares its valence electrons with fluorine atoms to form covalent bonds, using its valence electrons to achieve a stable electronic configuration.

VSEPR Theory

The Valence Shell Electron Pair Repulsion (VSEPR) theory is a model used to predict the geometry of molecules based on the repulsion between the electron pairs in the valence shell of atoms. This theory is very helpful to understand why molecules adopt certain shapes.

The VSEPR theory posits that because electron pairs repel each other, they will arrange themselves as far apart as possible in three-dimensional space. In \( \mathrm{ClF}_3 \), the chlorine atom is surrounded by three bonded pairs of electrons (from \( \mathrm{Cl-F} \) bonds) and two lone pairs. Due to the repulsion, the \( \mathrm{ClF}_3 \) molecule adopts a "T-shaped" geometry to minimize the repulsion and electronic crowding. Understanding the principles of VSEPR allows us to predict molecular shapes and understand the spatial arrangement of molecules in various compounds.