Textbook Question
By referring only to the periodic table, select (a) the most electronegative element in group 13; (b) the least electronegative element in the group As, Se and Br;
10. Periodic Properties of the Elements
Periodic Trend: Electronegativity
Multiple Choice
Which of the following statements accurately describes the polarity and electronegativity of water (H_2O)?
A
Water is a polar molecule because oxygen is more electronegative than hydrogen, resulting in a partial negative charge on oxygen.
B
Water is polar because hydrogen is more electronegative than oxygen, causing a partial negative charge on hydrogen.
C
Water is nonpolar because its molecular geometry is linear, leading to an even distribution of charge.
D
Water is a nonpolar molecule because hydrogen and oxygen have similar electronegativities.
Verified step by step guidance1
Recall that electronegativity is the tendency of an atom to attract electrons in a chemical bond. Oxygen has a higher electronegativity than hydrogen.
Understand that in a water molecule (H\_2O), the oxygen atom pulls the shared electrons in the O-H bonds closer to itself, creating a partial negative charge (\(\delta\)-) on oxygen and partial positive charges (\(\delta\)+) on the hydrogens.
Recognize that the shape of the water molecule is bent (angular), not linear, due to the two lone pairs on oxygen, which causes an uneven distribution of charge.
Combine the difference in electronegativity and the bent molecular geometry to conclude that water has a net dipole moment, making it a polar molecule.
Therefore, the correct description is that water is polar because oxygen is more electronegative than hydrogen, resulting in a partial negative charge on oxygen.
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