AP BIOLOGY

Detailed explanation-1: -In the case of water, hydrogen bonds form between neighboring hydrogen and oxygen atoms of adjacent water molecules. The attraction between individual water molecules creates a bond known as a hydrogen bond.

Detailed explanation-2: -Strong linkages-called covalent bonds-hold together the hydrogen (white) and oxygen (red) atoms of individual H2O molecules. Covalent bonds occur when two atoms-in this case oxygen and hydrogen-share electrons with each other.

Detailed explanation-3: -Each water molecule can form two hydrogen bonds involving their hydrogen atoms plus two further hydrogen bonds utilizing the hydrogen atoms attached to neighboring water molecules. These four hydrogen bonds optimally arrange themselves tetrahedrally around each water molecule as found in ordinary ice (see right).

Detailed explanation-4: -Water (H2O), like hydrogen fluoride (HF), is a polar covalent molecule. When you look at a diagram of water (see Fig. 3-2), you can see that the two hydrogen atoms are not evenly distributed around the oxygen atom.

Detailed explanation-5: -[2, 8] However, these numbers are affected by the higher average number of hydrogen bonds per molecule in D2O (3.76) than in H2O (3.62).