Final answer:
Dust grains in space grow into larger clumps due to gravitational attraction and chemical bonding in dense parts of the interstellar medium. This process of accumulation and growth, particularly in molecular clouds, forms larger structures and contributes to the formation of complex molecules.
Step-by-step explanation:
Grains attract other grains and grow into larger clumps due to gravitational attraction and chemical bonding.
In dense areas of the interstellar medium, such as molecular clouds, dust grains produced by stars come in contact and stick together, growing in size. This accumulation process is partly due to gravity pulling the particles towards each other, and the particles' ability to chemically bond or gather additional atoms from the surrounding gas. Over time, the joined particles can grow into larger clumps and facilitate the formation of complex molecules.
Gravitational attraction is a universal force acting on all matter, including interstellar dust grains, causing them to move towards one another. When this occurs in environments abundant with gas and dust, it results in the aggregation and growth of these grains into larger structures. This process is a fundamental part of star and planet formation, contributing to the cosmic cycle of matter.