Determine the number of valence electrons in dimethyl ether ((CH3)2O) and then draw the corresponding Lewis structure

Determine the number of valence electrons in dimethyl ether ((CH3)2O) and then draw the corresponding Lewis structure.

The correct answer and explanation is :

Valence Electrons in Dimethyl Ether (CH₃OCH₃)

Dimethyl ether, also known as (CH₃)₂O, consists of two methyl groups (CH₃) attached to an oxygen atom. To determine the number of valence electrons in dimethyl ether, we follow these steps:

1. Count the valence electrons for each atom:

• Carbon (C): Carbon is in Group 14 of the periodic table, so it has 4 valence electrons. Each CH₃ group contains one carbon atom, and since there are two CH₃ groups, the total number of valence electrons contributed by carbon is:
  [
  2 \times 4 = 8 \, \text{electrons}
  ]
• Hydrogen (H): Hydrogen is in Group 1 of the periodic table and has 1 valence electron. Each CH₃ group contains three hydrogens, and there are two CH₃ groups, so the total number of valence electrons contributed by hydrogen is:
  [
  2 \times 3 = 6 \, \text{electrons}
  ]
• Oxygen (O): Oxygen is in Group 16 of the periodic table and has 6 valence electrons. Since there is one oxygen atom in the structure, it contributes 6 valence electrons.

1. Add up the valence electrons:
   [
   8 \, (\text{from C}) + 6 \, (\text{from H}) + 6 \, (\text{from O}) = 20 \, \text{valence electrons}
   ]

Thus, dimethyl ether has 20 valence electrons in total.

Lewis Structure of Dimethyl Ether

Now, let’s draw the Lewis structure for (CH₃)₂O.

1. Arrange the atoms:

• The oxygen atom is in the center, with the two CH₃ groups (each containing one carbon atom) attached to it. Oxygen typically forms two bonds, so it will bond with each methyl group (CH₃).

1. Distribute the electrons:

• Place two electrons (one bond) between the oxygen and each carbon in the CH₃ groups.
• Each C-H bond in the CH₃ groups involves two electrons, and there are three hydrogens around each carbon, so these bonds are drawn as single bonds.

1. Place remaining electrons:

• After all bonds are made, the remaining electrons are placed as lone pairs on the oxygen atom.

1. Double-check the octet rule:

• Oxygen has 8 electrons around it (two bonds to carbon, each bond representing two electrons, and two lone pairs of electrons).
• Each carbon has 8 electrons around it (three bonds to hydrogen and one bond to oxygen).

Thus, the correct Lewis structure for dimethyl ether (CH₃OCH₃) shows oxygen in the center with two single bonds to the carbon atoms, and each carbon atom has three single bonds to hydrogen atoms. The oxygen atom also has two lone pairs.

Final Structure:

H   H
 |   |
H-C-O-C-H
 |   |
 H   H

In this structure, each line represents a single bond (two electrons), and the structure satisfies the octet rule for all atoms involved.