[jnimagine]

How is the bond angle for Cl-C-Cl in dichloromethane different from H-C-H bond angle of CH4? Is it smaller??

[AWK]

CH₂F₂ 108.3 deg. (all in gas phase)
CH₂Cl₂ 112.0
CH₂Br₂ 113.2

[nj_bartel]

why CF₂ bond angle smaller than CH₂ bond angle AWK?  Not immediately seeing it.  Assuming that for chlorine and onward the larger bond angle is due to electron repulsion due to the large shells.

[AWK]

Taking electronegativities of hydrogen and fluorine into account the electron pairs of bonds are much closer C atom in C-H bond and much closer the F atom in C-F bonds. Moreover electron withdrawing from the C atom by F cause the electron pairs of C-H are shifted slightly in the direction the C atom comparing to CH_4. Higher repulsion between electron pairs of C-H than that of C-F bond cause increasing H-C-H angle over F-C-F angle.

[nj_bartel]

Makes sense, thanks.