VSEPR theory structures???

Question

According to VSEPR theory which molecule is linear:

(a) H2O

(b) OF2

(c)CH4

(d)CO2

(e) PCl5

Answer 1

(a) H2O - bent

(b) OF2 - bent

(c)CH4 - tetrahedral

(d)CO2 - linear

(e) PCl5 - trigonal bipyramidal

Answer 2

VSEPR Theory deals with the bonds surrounding the central atom.  The central atom is typically the most electronegative atom (that is not Hydrogen).  Also, if Carbon is present it is typically the central atom.

Then you count the number of bonds (double-bonds and triple-bonds count as one) and the number of lone pairs around the central atom.  The total number (bonds plus lone-pairs) determines the basic geometry, then modify it according to the number of lone pairs (link follows).

Therefore, H2O would have Oxygen as the Central Atom,  and H-O-H will have 2 bonds and 2 lone pairs a total of 4.  Which is tetrahedral geometry, which is modified to be bent.

Also, CO2 will have Carbon as O=C=O the central atoms has 2 bonds and 0 line pairs a total of 2.  Which is linear geometry.

Hope this helps

Answer 3

(d) CO2