Write the electron dot structure for ethylene

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Write the electron dot structure for ethylene, C2H4.
a. What is the total number of available valence electrons?_
b. In the space below, write the atomic symbols, then add the bonding electron pairs. Finally distribute any
non-bonding electron pairs.
c. If there are not enough valence electrons remaining for the carbon atoms, consider the possibility of
having a multiple bond between the two carbon atoms. If there is a double covalent bond between the
carbon atoms (sharing of 4 valence electrons), can each carbon satisfy the Octet Rule?

The correct answer and explanation is :

Ethylene (C₂H₄) Electron Dot Structure

Ethylene (C₂H₄) is a simple hydrocarbon consisting of two carbon (C) atoms and four hydrogen (H) atoms. Here’s how to draw the electron dot structure for ethylene and answer your questions.

a. Total Number of Available Valence Electrons

  • Carbon (C) is in Group 14 of the periodic table, so each carbon atom has 4 valence electrons.
  • Hydrogen (H) is in Group 1, so each hydrogen atom has 1 valence electron.

The total number of valence electrons is:

  • For 2 carbon atoms: ( 2 \times 4 = 8 ) valence electrons
  • For 4 hydrogen atoms: ( 4 \times 1 = 4 ) valence electrons

Thus, the total number of valence electrons = ( 8 + 4 = 12 ) valence electrons.

b. Drawing the Atomic Symbols, Bonding Pairs, and Non-Bonding Electrons

  1. Carbon and Hydrogen Configuration:
  • Each hydrogen atom forms a single bond with a carbon atom. This uses 2 valence electrons for each hydrogen-carbon bond.
  • Ethylene has 2 carbon atoms, each bonded to 2 hydrogen atoms.
  1. Bonding Between Carbon Atoms:
  • Each carbon atom needs 4 electrons to complete its octet, but they are only sharing 2 electrons with each hydrogen atom (forming single bonds).
  • Thus, the two carbon atoms will share 4 electrons (forming a double bond) to complete their octet.
  1. Electron Dot Structure:
  • Each carbon atom is shown with 4 valence electrons in total, including 2 electrons for each bond with a hydrogen and 4 shared electrons between the two carbon atoms.
  • The hydrogen atoms each have 1 bond (and no lone pairs).

So, the electron dot structure of ethylene looks like this:

H     H
 |     |
C = C
 |     |
H     H

In this structure, the “=” sign represents the double bond (2 shared electron pairs) between the two carbon atoms.

c. Can Each Carbon Satisfy the Octet Rule with a Double Bond?

Yes, each carbon atom can satisfy the Octet Rule by forming a double bond between the two carbon atoms. Here’s how:

  • Each carbon atom has 4 valence electrons. By forming two single bonds with hydrogen atoms (each hydrogen contributing 1 electron), each carbon shares 2 electrons with each hydrogen.
  • The carbon-carbon double bond involves the sharing of 4 electrons (2 electrons in each bond), bringing the total number of electrons shared by each carbon atom to 8 (4 from hydrogen bonds + 4 from the carbon-carbon double bond).

Thus, each carbon atom effectively has 8 electrons in its valence shell, fulfilling the octet rule.

  • Hydrogen atoms, on the other hand, only need 2 electrons to complete their valence shell (following the duet rule), which they achieve by sharing 1 electron with the carbon atoms.

Explanation (300 words):

The electron dot structure for ethylene (C₂H₄) reveals how atoms achieve stable electron configurations by sharing electrons. Carbon atoms, with 4 valence electrons, seek 4 more electrons to fill their valence shell and satisfy the Octet Rule, which states that atoms tend to form bonds until they have 8 electrons in their outer shell (except for hydrogen, which follows the duet rule).

The hydrogen atoms each need just 2 electrons to complete their outer shell. In the ethylene molecule, each hydrogen forms a single bond with a carbon atom, providing each hydrogen with its required 2 electrons.

The two carbon atoms in ethylene bond with each other by a double bond (represented by a “=” in the dot structure). A double bond involves sharing 4 electrons (2 pairs), which allows each carbon atom to achieve an octet of electrons, satisfying the Octet Rule. Without the double bond, each carbon atom would only have 6 electrons in its valence shell, which would not satisfy the octet rule.

The total number of valence electrons in the molecule (12) is used up in the bonding process: 8 electrons are used for the carbon-hydrogen bonds (4 bonds), and 4 electrons are shared between the two carbon atoms in the double bond. As a result, all atoms—carbon and hydrogen—achieve stable electron configurations, with the carbon atoms following the Octet Rule and the hydrogen atoms following the Duet Rule.

This bonding arrangement ensures the stability of the ethylene molecule.

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