Write the electron dot structure of the ethene molecule $\text{ }{{\text{C}}_{\text{2}}}{{\text{H}}_{\text{4}}}\text{ }$ .

To draw the electron dot structure of ethene, which has the chemical formula C₂H₄, we first need to understand its molecular composition and bonding. Ethene is an alkene, meaning it contains a carbon-carbon double bond. Let's break down the steps to create its electron dot structure.

Step 1: Count the Valence Electrons

Each carbon atom has four valence electrons, and each hydrogen atom has one. Therefore, for ethene:

• 2 Carbon atoms: 2 × 4 = 8 valence electrons
• 4 Hydrogen atoms: 4 × 1 = 4 valence electrons

In total, ethene has 8 + 4 = 12 valence electrons to work with.

Step 2: Arrange the Atoms

In ethene, the two carbon atoms will be at the center of the structure, bonded to each other, and each carbon will be bonded to two hydrogen atoms. The basic skeleton can be represented as:

• H - C - C - H

Step 3: Form the Bonds

To satisfy the bonding requirements, we need to create a double bond between the two carbon atoms. Each carbon atom will share two of its electrons with the other carbon atom. This results in:

• C=C (double bond)

Now, each carbon atom will also bond with two hydrogen atoms. The complete structure can be visualized as:

• H - C = C - H

Step 4: Distribute the Electrons

Now, let's represent the electrons in the structure. Each bond (single or double) is represented by a pair of dots or a line. For ethene, the double bond between the carbon atoms can be shown as:

• H : C = C : H

Here, the colons (:) represent the shared pairs of electrons. Each hydrogen atom is bonded to a carbon atom with a single bond, represented by a single pair of dots.

Final Electron Dot Structure

Putting it all together, the electron dot structure of ethene can be represented as:

H : C = C : H

In this representation, each line or pair of dots indicates a bond, and you can see how the electrons are shared between the atoms. This structure effectively illustrates the bonding in ethene, highlighting the double bond between the carbon atoms and the single bonds with hydrogen atoms.

Understanding the Importance

Recognizing the electron dot structure is crucial because it helps us understand the molecular geometry and reactivity of ethene. The presence of the double bond makes ethene more reactive than alkanes, which only have single bonds. This reactivity is fundamental in organic chemistry, especially in reactions like polymerization, where ethene can be transformed into polyethylene.