Question

draw the lewis dot structures for the following (1*5=5 points). show complete work clearly establishing your method to draw the structures - electron accounting method or valence electron method
a) c₂h₄
b) po₄³⁻
c) cacl₂
d) cocl₂
e) o₂

Explanation:

Step1: Determine valence electrons for C₂H₄

Carbon has 4 valence electrons and hydrogen has 1. For C₂H₄, 2×4 + 4×1=12 valence electrons.

Step2: Arrange atoms

Place the two carbon atoms in the center and hydrogen atoms around them.

Step3: Distribute electrons

First, form single - bonds between C - H and C - C. Each single - bond uses 2 electrons. After forming 4 C - H and 1 C - C single - bonds, 10 electrons are used. Then, add a double - bond between the two carbon atoms to satisfy the octet rule for carbon.

Step4: Determine valence electrons for PO₄³⁻

Phosphorus has 5 valence electrons, oxygen has 6, and there is an extra 3 electrons due to the 3 - charge. So 5+4×6 + 3=32 valence electrons.

Step5: Arrange atoms

Place phosphorus in the center and oxygen atoms around it.

Step6: Distribute electrons

Form single - bonds between P - O first. After using 8 electrons for 4 single - bonds, distribute the remaining 24 electrons as lone - pairs on oxygen atoms to satisfy the octet rule.

Step7: Determine valence electrons for CaCl₂

Calcium is a metal and chlorine is a non - metal. Calcium has 2 valence electrons and chlorine has 7. So 2+2×7 = 16 valence electrons.

Step8: Electron transfer

Calcium donates its 2 electrons to the two chlorine atoms to form Ca²⁺ and 2Cl⁻. The Lewis structure shows Ca²⁺ and two Cl⁻ ions with 8 electrons around each Cl⁻.

Step9: Determine valence electrons for COCl₂

Carbon has 4, oxygen has 6 and chlorine has 7. So 4+6+2×7=24 valence electrons.

Step10: Arrange atoms

Place carbon in the center, oxygen and two chlorine atoms around it.

Step11: Distribute electrons

Form single - bonds between C - Cl and a double - bond between C - O. After using 8 electrons for 2 C - Cl and 1 C = O, distribute the remaining 16 electrons as lone - pairs on oxygen and chlorine atoms to satisfy the octet rule.

Step12: Determine valence electrons for O₂

Oxygen has 6 valence electrons. So 2×6 = 12 valence electrons.

Step13: Arrange atoms

Place two oxygen atoms next to each other.

Step14: Distribute electrons

Form a double - bond between the two oxygen atoms first. After using 4 electrons for the double - bond, distribute the remaining 8 electrons as lone - pairs on each oxygen atom to satisfy the octet rule.

Answer:

a) For C₂H₄: H are single - bonded to C and there is a C = C double - bond.
b) For PO₄³⁻: P is at the center with single - bonded O atoms and lone - pairs on O.
c) For CaCl₂: Ca²⁺ and two Cl⁻ ions with 8 electrons around Cl⁻.
d) For COCl₂: C is at the center with double - bonded O and single - bonded Cl atoms and lone - pairs on O and Cl.
e) For O₂: There is a double - bond between two O atoms and lone - pairs on each O.