PPT Slide

31

• Three electron groups around the central atom repel  each other to the corners of an equilateral triangle.

• When the three electron groups are bonding, the  molecular shape is trigonal planar; symbol is AX 3.

• Boron trifluoride (BF 3), is  an AX 3 example.

• Nitrate (NO3–) is also AX3.

• Its resonance hybrid has three identical 1 1 ¹ 3 bonds,  so the ideal 120° bond angle is observed:

Concept 10-8. Why double bonds and lone pairs cause deviations from ideal bond angles

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