Draw a Lewis structure for the following molecules:
e. BeCl₂ (Note: This molecule does not follow the octet rule.)

Verified step by step guidance

1. Step 1: Identify the total number of valence electrons in the molecule. Beryllium (Be) is in Group 2 of the periodic table and has 2 valence electrons. Chlorine (Cl) is in Group 17 and has 7 valence electrons. Since there are two chlorine atoms, the total number of valence electrons is: 2 (from Be) + 7 × 2 (from Cl) = 16 valence electrons.
2. Step 2: Determine the central atom. Beryllium (Be) is less electronegative than chlorine (Cl), so Be will be the central atom, and the two chlorine atoms will be bonded to it.
3. Step 3: Draw single bonds between the central atom (Be) and each chlorine atom. Each single bond represents 2 electrons. After forming these bonds, subtract the electrons used from the total valence electrons. For BeCl₂, 2 bonds × 2 electrons = 4 electrons used, leaving 16 - 4 = 12 electrons.
4. Step 4: Distribute the remaining electrons to satisfy the octet rule for the chlorine atoms. Each chlorine atom needs 8 electrons in its valence shell, including the 2 electrons from the bond with Be. Place the remaining electrons as lone pairs around the chlorine atoms. Each chlorine will have 6 lone-pair electrons, completing their octets.
5. Step 5: Check the central atom (Be). Beryllium is an exception to the octet rule and is stable with only 4 electrons in its valence shell (from the two single bonds with chlorine). Verify that all valence electrons are accounted for and that the structure is valid.

Key Concepts

Lewis Structure

A Lewis structure is a diagram that represents the bonding between atoms in a molecule and the lone pairs of electrons that may exist. It uses dots to represent electrons and lines to represent bonds, helping to visualize the arrangement of atoms and the distribution of electrons. Understanding how to draw Lewis structures is essential for predicting molecular geometry and reactivity.

Octet Rule

The octet rule is a chemical guideline that states atoms tend to bond in such a way that they each have eight electrons in their valence shell, achieving a stable electron configuration similar to that of noble gases. However, some molecules, like BeCl₂, do not follow this rule, as beryllium can be stable with fewer than eight electrons. Recognizing exceptions to the octet rule is crucial for accurately representing certain molecules.

Molecular Geometry

Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. It is influenced by the number of bonding pairs and lone pairs of electrons around the central atom, which can affect the molecule's shape and properties. Understanding molecular geometry is important for predicting how molecules will interact with each other and their reactivity in chemical reactions.