Question

Determine the molecular shape, bond angle, and hybrid orbitals for each molecule. $$ \mathrm{BeF}_{2} $$

Short answer

The molecular shape of BeF2 is linear, the bond angle is 180°, and the hybrid orbitals are sp.

Step-by-step solution

Determine the Central Atom

In BeF2, the central atom is Beryllium (Be). It is the least electronegative atom in the molecule.

Draw the Lewis Structure

For BeF2, we first count the total number of valence electrons. Beryllium has 2 valence electrons and each Fluorine atom has 7 valence electrons. So the total number of valence electrons is 2 + 7(2) = 16. However, Beryllium is an exception to the octet rule, and it can accommodate only four electrons. So, the Lewis structure for BeF2 is as follows: Be -- F -- F

Determine the Electron Pair Geometry

The electron pair geometry is based on the arrangement of electron pairs around the central atom. In BeF2, there are only two bonding pairs of electrons around the central Be atom. Hence, the electron pair geometry is linear.

Determine the Molecular Geometry

Since there are no lone pairs on the central atom, the molecular geometry is the same as the electron pair geometry. Thus, the molecular geometry of BeF2 is also linear.

Identify the Bond Angle

In a linear molecule, the bond angle is 180 degrees. So, the bond angle of the BeF2 molecule is 180°.

Identify the Hybrid Orbitals

To identify the hybrid orbitals, we look at the electron pair geometry. For a linear electron pair geometry, the central atom uses sp hybrid orbitals. Therefore, Beryllium in BeF2 uses sp hybrid orbitals. To summarize, the molecular shape of BeF2 is linear, the bond angle is 180 degrees, and the hybrid orbitals are sp.

Key concepts

Bond Angle

Bond angle refers to the angle formed between two bonds that have a common atom, often a central atom. In molecular geometry, understanding bond angles is essential to predicting the shape and properties of a molecule. For the BeF\( _2 \) molecule, the bond angle is determined by its linear shape. The central atom, Beryllium (Be), is bonded to two Fluorine atoms, and these bonds form a perfect 180-degree angle with each other.
This is characteristic of linear molecular geometries, where the goal is to minimize the electron pair repulsion according to VSEPR (Valence Shell Electron Pair Repulsion) theory.When no lone pairs are affecting the geometry, as seen in BeF\(_2\), the bond angles will usually remain consistent with their predicted geometric value, ensuring the molecule remains balanced.

Hybrid Orbitals

Hybrid orbitals are a concept in chemistry where atomic orbitals mix to form new orbitals. These new orbitals are used by atoms in bonding to create stable molecular structures with specific shapes.In BeF\(_2\), the central atom, Beryllium, utilizes sp hybridization. This occurs because Beryllium has two valence electrons and forms two bonds, one with each Fluorine atom.
During the sp hybridization, one s and one p orbital from Beryllium mix to form two equivalent sp hybrid orbitals.
These hybrid orbitals align linearly, explaining the linear molecular structure of BeF\(_2\) and ensuring optimal bond angles of 180 degrees.Hybrid orbitals are fundamental for explaining the geometry and stability of molecules, allowing us to predict how they will behave and interact in chemical reactions.

Lewis Structure

A Lewis structure is an essential tool in chemistry to illustrate the bonding and arrangement of atoms within a molecule. It displays all the valence electrons as dots and highlights how atoms share or transfer electrons to achieve stable electron configurations.For BeF\(_2\), Beryllium is the central atom and an exception to the octet rule, accommodating only 4 electrons. Each Fluorine atom shares one of its electrons with Beryllium, forming single bonds. Fluorine achieves a full octet configuration by this bonding.The Lewis structure for BeF\(_2\) is simple:

• The central Be atom, with one bonding line to each F atom.
• Each F atom is surrounded by three pairs of dots, representing the three lone pairs of electrons.

Such representations help us visualize molecular geometry and predict chemical behavior efficiently.

Central Atom

The concept of a central atom is crucial when determining the structure and properties of a molecule. The central atom is typically the least electronegative and is used as a reference point for constructing the molecule's structure.In BeF\(_2\), Beryllium is chosen as the central atom because it is less electronegative than Fluorine. This means Be will share its valence electrons instead of holding them as tightly as Fluorine.Being the backbone of the molecule, the central atom's properties and available orbitals significantly influence the molecule's geometry. In the case of Be, its capability to form two bonds gives BeF\(_2\) its linear shape, highlighted by its 180-degree bond angles.Understanding the role of the central atom aids in predicting how a molecule will look and behave, making it a vital part of molecular geometry.