Question

Valence Bond Theory Draw orbital diagrams (boxes with arrows in them) to represent the electron configurations of carbon before and after sp hybridization.

Short answer

The electron configuration of carbon is 1s² 2s² 2p². Before sp hybridization, draw two filled boxes (1s, 2s) and three boxes for 2p orbitals, with the first two containing one electron each. For sp hybridization, promote an electron from the 2s orbital to an empty 2p orbital, then combine the 2s and one 2p orbital to form two sp hybrid orbitals, and represent each with one electron in a box.

Step-by-step solution

Understanding Electron Configuration of Carbon

First, determine the electron configuration of a neutral carbon atom. Carbon, with an atomic number of 6, has 6 electrons. The electron configuration is thus 1s² 2s² 2p², with two electrons in the 1s orbital, two in the 2s orbital, and two electrons in the 2p orbitals.

Representing the Ground State Orbitals

Draw two boxes to represent the 1s and 2s orbitals, both completely filled with two electrons shown as arrows pointing in opposite directions to indicate the Pauli Exclusion Principle. Then, draw three boxes beside them to represent the 2p orbitals with one electron in the first two p orbitals and none in the third, pairing the electrons with opposite spins.

Showing Electron Rearrangement for sp Hybridization

Demonstrate the process of sp hybridization that occurs in carbon when it is involved in covalent bonding. To do this, 'promote' one of the 2s electrons to an empty 2p orbital. Then, combine one 2s orbital and one 2p orbital to form two sp hybrid orbitals. This will result in a total of two sp orbitals and two remaining p orbitals.

Drawing sp Hybridized Orbitals

Draw one box for each of the two sp hybrid orbitals and place one arrow in each to represent the single electron. Then, draw the two remaining p orbitals each with one electron. These diagrams illustrate the electron configuration of carbon undergoing sp hybridization, ready to form two sigma bonds with the sp orbitals and two pi bonds with the p orbitals.

Key concepts

Valence Bond Theory

Valence Bond Theory (VBT) is a fundamental concept in chemistry that explains the formation and nature of covalent bonds between atoms. According to VBT, a covalent bond forms when the half-filled orbitals of two atoms overlap, allowing their unpaired electrons to pair up and become shared between the atoms. These shared electron pairs are what we recognize as covalent bonds.

One of the key aspects of VBT is hybridization, which describes the mixing of atomic orbitals to form new, equivalent hybrid orbitals that are oriented in specific directions to maximize the overlap and therefore the strength of the bonds formed.

In the example of carbon's sp hybridization, VBT helps explain how carbon can form sturdy bonds in compounds like ethylene by the rearrangement and merging of its electron orbitals, optimizing its structure for bonding with other atoms. The concept of VBT ties in closely with the practical exercise of drawing orbital diagrams to illustrate these overlaps.

Electron Configuration

Electron configuration refers to the distribution of electrons in an atom's orbitals, governed by a set of rules known as quantum mechanics. These rules dictate the arrangement of electrons in order of increasing energy levels. In a neutral carbon atom, for example, the configuration is \( 1s^2 2s^2 2p^2 \), indicating the filling of the orbitals from the lowest to the highest energy.

When electrons are paired in an orbital, they must have opposite spins, a consequence of the Pauli Exclusion Principle, which is represented by arrows pointing in opposite directions in orbital diagrams. Moreover, Hund's Rule states that electrons will fill degenerate (equal in energy) orbitals singly and with parallel spins before pairing up. This electron configuration is the starting point for understanding more complex concepts, such as sp hybridization, which modifies the electron arrangement to accommodate bonding.

Orbital Diagrams

Orbital diagrams are visual representations that show the distribution of electrons in an atom's orbitals. These diagrams use boxes (or lines) to depict orbitals and arrows to indicate electrons, with their direction representing the electron's spin. They provide a clear way to visualize electron configuration and the application of principles such as Hund's Rule and the Pauli Exclusion Principle.

For the carbon atom before sp hybridization, we would draw two filled boxes for the \( 1s \) orbitals, another two for the \( 2s \) orbitals, and three for the \( 2p \) orbitals, with the first two having one electron each and the last one empty. After sp hybridization, one electron from the \( 2s \) orbital is promoted to the empty \( 2p \) orbital, forming two sp hybrid and two remaining p orbitals. The exercise walks students through the visualization of this crucial step, showing the transformed state tailored for forming covalent bonds.

These orbital diagrams not only assist in understanding the spatial arrangement and energy levels but also provide a roadmap for predicting the chemical behavior and bonding capability of an atom, such as carbon, in chemical reactions.