Water Molecule Geometry and Properties

The video tutorial explains the molecular geometry of water (H2O). It begins with drawing the Lewis structure, showing that oxygen has six valence electrons and hydrogen has one, resulting in eight total valence electrons. The tutorial then discusses the concept of steric number, which is four for water, and the presence of two lone pairs. These lone pairs push the hydrogen atoms down, resulting in a bent molecular geometry with a bond angle of 104.5 degrees, different from the generic 109.5 degrees. The video concludes with a summary of these concepts.

What is the total number of valence electrons in a water molecule?

• 6

• 12

• 8

• 10

How many valence electrons does oxygen contribute to the water molecule?

• 5

• 6

• 7

• 4

What is the steric number of the oxygen atom in a water molecule?

• 3

• 2

• 4

• 5

How many lone pairs are present on the oxygen atom in water?

• 3

• 2

• 1

• 4

What type of molecular geometry does water exhibit?

• Linear

• Bent

• Trigonal Planar

• Tetrahedral

What is the generic bond angle for a molecule with a steric number of four?

• 104.5°

• 120°

• 109.5°

• 90°

What is the actual bond angle in a water molecule?

• 109.5°

• 120°

• 104.5°

• 90°

Why is the bond angle in water less than the generic 109.5°?

• Due to the repulsion between lone pairs

• Due to the presence of hydrogen bonds

• Because of the large size of hydrogen atoms

• Because of the small size of oxygen atom

What effect do lone pairs have on the geometry of a water molecule?

• They increase the bond angle

• They decrease the bond angle

• They have no effect

• They make the molecule linear

What is the main reason for the bent shape of the water molecule?

• Low electronegativity of oxygen

• High electronegativity of hydrogen

• Presence of lone pairs

• Presence of double bonds