1.   A nitro group is a molecular fragment consisting of a nitrogen atom bonded to two oxygen atoms.

2.   Initially, the elements and simple molecular fragments in the gas cloud are so diffuse that reactions between them are practically impossible.

3.   Molecular fragments and atoms can be attached to both the outside and the inside of buckyballs.

4.   The enzyme catalyzes the transfer of a molecular fragment, called an acetyl group, from a donor molecule to the antibiotic, rendering it ineffective.

5.   The new compound is a positively charged ion, or molecular fragment, consisting of five nitrogen atoms chemically bonded to each other in a V pattern.

6.   The scientists call the toxic molecular fragments free radicals and think they break down the collagen and elastin layers.