Trap One: the Particle Is Not the Substance
This is the big one. A single particle does not have the properties of the stuff it makes up. The particle doesn't melt, it doesn't expand, it isn't blue if the liquid is blue, and it isn't wet. Wet, blue and melting are things the whole crowd does together — never one particle. When iron melts, the iron particles don't go soft and runny; they just start sliding past each other instead of holding formation.
Trap Two: There's Nothing in the Gaps
In a gas the particles are far apart — so what's between them? The honest answer is nothing: empty space. Not air, not tiny bits of more stuff, not invisible jelly. People love to fill the gaps with “air”, but the air is the particles; between them is genuinely empty. This is exactly why a gas squashes so easily — you're just pushing particles into the empty space. A liquid barely squashes at all, because its particles are already touching with almost no gaps to close.
Trap Three: Heating Doesn't Make Particles Bigger
Heat a metal ball and it expands — true. But the particles themselves do not grow. They stay exactly the same size; they just vibrate harder and shove their neighbours a little further away, so the whole object takes up more room. Expansion is extra spacing, never bigger particles.
And the Quiet One: Melting Is Not Dissolving
Melting is a solid turning to liquid because you added heat — one substance, changing state. Dissolving is a solid disappearing into a liquid because it's spreading out among the liquid's particles — two substances mixing, no change of state needed. Sugar in cold tea dissolves; it doesn't melt. Keep them apart: melt = heat + one substance; dissolve = mixing + two substances.