Hi. This question made my mind busy for a while. I was eating chocolate and noticed how it melts slowly in time. I know the heat circulates in the room, but how do these molecules get affected exactly?
In: Chemistry
Imagine that atoms are little magnetic balls. Get a bunch and arrange them properly and you can make a little ball or a cube or some similar structure of little magnets all stuck together and they’ll stay that way.
Now whack that cube you made with a baseball bat and the magnets will all go flying off in different directions completely unstuck from one another, because the kinetic energy you imparted by smacking them is stronger than the magnetism that was holding them together.
It turns out that this is very, very similar to how matter behaves. “Heat” is just how much kinetic energy the atoms in something have, and you get a solid when the atoms have low enough kinetic energy that they can all stick together (because of electromagnetism) in an orderly fashion.
If you dump in a ton of kinetic energy into that orderly bundle of atoms so that they all go flying off in different directions, that’s a gas.
And if you put in enough to break them out of that orderly ball but not so much that they completely escape being bound together a bit, that’s a liquid.
Heat, aka the kinetic energy of the atoms, is also transferred pretty intuitively (when discussing on a simple, high level). If you have a table of billiard balls that are all stationary, that means they have little or no kinetic energy (i.e. they are “cold”) if you have a “hot” billiard ball, i.e. one moving very fast with a lot of kinetic energy, and you throw it on the table, it’s going to bump into the other billiard balls. This will slow down the fast billiard ball but cause the other balls to start moving.
Apply the same standard to the atoms making up the chocolate. They’re all stuck together in an orderly fashion. Then you touch something hotter against them and the high energy balls from the hot thing bump into the lower energy balls of the chocolate, causing them to move around more. Now that they’re moving more, they can’t hold together as well and start to break out of that ordered format they were in. This causes the chocolate to melt.
Different atoms have slightly different shapes and stronger or weaker magnetic attractions to other atoms. This affects what kids of shapes those atoms can make when all assembled and what other atoms they can easily stick to. The larger shapes that you can assemble the atoms into, and how they stick together, determine the properties of the material that the atoms are a part of.
This includes the melting point. That is, some shapes (like a ball, or cube, or stacked sheet layers) of atomic configurations will be more stable and keep the atoms locked in place better. Thus it takes more energy to knock the atom out of place, or less energy if the links are weaker. That’s why you can have something solid and hot touch the chocolate and cause it to melt, but the hot thing is still solid itself. The atoms have enough energy to knock the atoms in the chocolate loose, but are more firmly held in place themselves so it isn’t enough to shake *them* loose.
The colder an atom is the more it will stick to other atoms typically. Cold chocolate holds together but as the energy increases the bonds are going to start slipping.
The energy comes in as heat. It could be radiant heat like from a lamp or microwave. It could come from your hand or the air. The excited hot atoms in your hand wiggle the chocolate molecules until they get warm. Warm air molecules will bump into it and leave some of their energy behind. The lamp will send photons that get absorbed and transfer heat.
Objects are made of atoms which stick together. These groups of atoms have energy which makes them move, which we call heat. Atoms stick together because of chemical bonds. When an object has low heat, it doesn’t move much and sticks together. When it has high heat, it moves a lot and can break these bonds, making it flow as a liquid.
This is as simplified as I can make it, and more of an illustration of what goes on than the reality.
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