text: .  The atoms in the pencil are in motion, but not freely in motion.  The atoms are bound up in molecules which make up crystaline or cellular structures.  The metal atoms in the eraser holder are part of the metal crystaline matrix.  The carbon and other atoms of the eraser are parts of organic molecules which form strands which are interlinked.  The carbon, hydrogen and oxygen atoms of the wood are parts of cellulose molucules which formed the cell wall of the tree from which the wood was taken.  The "lead" of the pencil contains carbon molecules in fractured crystals of graphite, which are mixed with clay, which contains silicon, aluminum and oxygen in a crystaline structure.\n.  If you picture a ping pong ball tethered by a weak rubber band and knocked around by a mild shifting breeze, the ping pong ball would be "free" to move, but the rubber band would keep it moving about the same center.  A stronger breeze might have enough energy to break the rubber band and let the ping pong ball be blown wherever the wind goes.\n.  Atoms are of just the size that puts them on the brink of quantum mechanical uncertainty.  They are large enough that the uncertainty about their position is very small, even when their energy is know to a high degree of precision.  In quantum mechanics, this means that the amount they will wander is quite small, small enough that they remain bound to their neighbors in their molecular or crystaline arrangements.  Adding energy in the form of heat both increases the uncertainty about their position and increases the probability that their bonds will be broken.