To draw the Lewis structure for CCl2F2, with carbon as the central atom, we start by determining the number of valence electrons, the total number of electron groups, the electron geometry, the molecular shape, molecular polarity, and the major attractive forces.
a. Total Number of Valence Electrons
Carbon (C) has 4 valence electrons, and each chlorine (Cl) has 7, while each fluorine (F) also has 7. So:
- 1 C: 4 electrons
- 2 Cl: 2 × 7 = 14 electrons
- 2 F: 2 × 7 = 14 electrons
Adding these together gives a total of 4 + 14 + 14 = 32 valence electrons.
b. Total Number of Electron Groups
In CCl2F2, carbon is surrounded by 4 groups of electrons: 2 from the Cl atoms and 2 from the F atoms. Therefore, there are 4 electron groups.
c. Electron Geometry
Since there are 4 electron groups around the central carbon atom, the electron geometry is Tetrahedral.
d. Molecular Shape
The molecular shape also corresponds to a tetrahedral arrangement, as there are no lone pairs on the carbon atom. So, the molecular shape is Tetrahedral.
e. Molecular Polarity
Due to the difference in electronegativity between Cl and F atoms, and the fact that the C-Cl and C-F bonds are polar, the CCl2F2 molecule does not have a symmetrical distribution of charge. Hence, it is polar.
f. Major Attractive Force
The major attractive force in CCl2F2 is dipole-dipole interactions, due to its polar nature. These forces arise from the attraction between the positive end of one polar molecule and the negative end of another.