Question

in a water molecule, how do the electrical charges compare between oxygen and hydrogen atoms?
a the oxygen and hydrogen atoms are both neutral in charge.
b the oxygen atom is slightly positive in charge, while the hydrogen atoms are are slightly negative in charge.
c the oxygen atom is slightly negative in charge, while the hydrogen atoms are slightly positive in charge.
d the oxygen and hydrogen atoms are both slightly negative in charge.

Explanation:

In a water molecule ($H_2O$), the oxygen atom is more electronegative than hydrogen atoms. Electronegativity refers to the ability of an atom to attract shared electrons in a covalent bond. Since oxygen is more electronegative, it pulls the shared electrons in the $O - H$ bonds closer to itself. This causes the oxygen atom to have a slight excess of negative charge (slightly negative), and the hydrogen atoms, having less of the shared electron density, have a slight positive charge (slightly positive).

• Option a is incorrect because the distribution of electron density creates partial charges, so they are not both neutral in terms of the partial charges in the molecule.
• Option b has the charges reversed; oxygen should be slightly negative, not positive.
• Option d is incorrect as they can't both be slightly negative since electrons are shared and oxygen attracts them more.

Answer:

c. The oxygen atom is slightly negative in charge, while the hydrogen atoms are slightly positive in charge.