Molecular Geometry and Electron Pair Repulsion

The video tutorial explains the 3D structures of molecules like methane, ammonium, ammonia, and water. It introduces the electron pair repulsion theory, which dictates molecular shapes. Methane and ammonium ions have a tetrahedral shape with a bond angle of 109.5 degrees. Ammonia, with one lone pair, forms a pyramidal shape with a bond angle of 107 degrees. Water, with two lone pairs, forms a bent shape with a bond angle of 104 degrees. The video emphasizes the impact of lone pair repulsion on molecular geometry.

What is the shape of a methane (CH4) molecule?

• Linear

• Tetrahedral

• Trigonal planar

• Bent

What is the bond angle in a tetrahedral molecule like methane?

• 90 degrees

• 104 degrees

• 109.5 degrees

• 107 degrees

Which ion has a tetrahedral shape similar to methane?

• Ammonium ion (NH4+)

• Carbonate ion (CO3 2-)

• Hydroxide ion (OH-)

• Nitrate ion (NO3-)

How many bonding pairs are present in an ammonium ion (NH4+)?

• Two

• Four

• Three

• Five

What is the effect of lone pair repulsion on the shape of ammonia (NH3)?

• It becomes linear

• It becomes trigonal planar

• It becomes pyramidal

• It becomes square planar

What is the bond angle in ammonia (NH3) due to lone pair repulsion?

• 90 degrees

• 109.5 degrees

• 104 degrees

• 107 degrees

How many lone pairs are present in a water (H2O) molecule?

• One

• Two

• Three

• Four

What is the shape of a water (H2O) molecule?

• Bent

• Trigonal planar

• Tetrahedral

• Linear

What is the bond angle in a water (H2O) molecule due to lone pair repulsion?

• 90 degrees

• 104 degrees

• 109.5 degrees

• 107 degrees

What common feature do methane, ammonium ion, ammonia, and water share in terms of electron pairs?

• All have a linear shape

• All have no lone pairs

• All have four electron pairs

• All have three bonding pairs