What is the total number of valence electrons in the compound C2H6O – also write out the Lewis dot structure of this compound and submit with your written work. Hint for structure: one of the H atoms is bonded to the O; the O also has a bond to C
The Correct Answer and Explanation is:
Total Number of Valence Electrons in C₂H₆O
To determine the total number of valence electrons in the compound C₂H₆O (ethanol or dimethyl ether, depending on structure), we add up the valence electrons for each atom:
- Carbon (C): 4 valence electrons × 2 atoms = 8 electrons
- Hydrogen (H): 1 valence electron × 6 atoms = 6 electrons
- Oxygen (O): 6 valence electrons × 1 atom = 6 electrons
Total = 8 (C) + 6 (H) + 6 (O) = 20 valence electrons
Lewis Dot Structure of C₂H₆O (Ethanol)
Based on the hint: “one of the H atoms is bonded to the O; the O also has a bond to C,” the structure is ethanol (CH₃CH₂OH), not dimethyl ether.
H H H H
| | | |
H — C — C — O — H
| |
H H
Lewis Dot Structure (simplified with dots for lone pairs on oxygen):
- Each H forms 1 bond.
- Each C forms 4 bonds.
- Oxygen forms 2 bonds and has 2 lone pairs (4 electrons).
H H H ..
| | | :
H–C–C–O–H
| |
H H
:
..
Explanation
The compound C₂H₆O contains two carbon atoms, six hydrogen atoms, and one oxygen atom. To determine its structure and bonding, we begin with calculating the total number of valence electrons. Carbon, in group 14, contributes 4 valence electrons each; hydrogen, in group 1, contributes 1 electron each; and oxygen, in group 16, contributes 6 valence electrons. Thus, the molecule contains:
- 2 Carbons × 4 = 8 e⁻
- 6 Hydrogens × 1 = 6 e⁻
- 1 Oxygen × 6 = 6 e⁻
Total = 20 valence electrons
The structure depends on how atoms are connected. The hint specifies that a hydrogen is bonded to oxygen and that oxygen is also bonded to carbon. This setup suggests the molecule is ethanol (CH₃CH₂OH), where an –OH group is attached to an ethyl chain.
Ethanol’s structure begins with a carbon (C) bonded to three hydrogens (H), making a methyl group (CH₃). This carbon is bonded to another carbon, which forms a methylene group (CH₂). The second carbon bonds to an oxygen atom (O), which in turn bonds to a hydrogen atom (H), forming a hydroxyl group (–OH). Oxygen completes its octet with two lone pairs.
Each atom satisfies the octet rule (or duet for hydrogen) and the total bonding uses up all 20 valence electrons. The molecule is stable, neutral, and reflects typical covalent bonding. Ethanol is a polar molecule due to the O–H bond, contributing to its solubility in water and other polar solvents.
