eli5: how does chemistry work? do the particles fuse together? do they slit themselves apart and give one of the other particles half of itself and they trade like clothes? I’m so confused
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Subatomic particles are like little magnets that snap together in different patterns and the patterns have different properties
So, you probably already know – but here is a refresher – that atoms are made of three particles: a nucleus made of protons and neutrons, and electrons whizzing around the nucleus in a sort of “cloud”. Protons have a positive charge, neutrons have no charge, and electrons have a negative charge. The electrons are where are all the chemistry happens.
Atoms are trying to find a *stable state*. Imagine a ball on top of a hill. It isn’t stable, it wants to roll down the hill. You can poke it and move it and it’ll tumble down the hill and release a bunch of energy. Once it gets to the bottom it has nowhere else to go, so it is now stable. You can poke it and move it a little bit, but it really doesn’t want to go anywhere and you have to add a lot of energy to roll it back up a hill.
Atoms are trying to be stable in two ways. The first is to be electrically neutral. Atoms can’t give up or gain protons very easily, but they *can* give up or gain electrons. If there are more protons in the nucleus than there are electrons around the atom, the atom will have an overall positive charge. Since opposite charges attract, the atom will tend to attract an electron and add it to the electron cloud around the atom. If there are more electrons, the atom will be overall negatively charged, and since like charges repel, the electrons will tend to force the extra electron away until it flies off. These two charges are constantly fighting each other – the positive protons are trying to keep electrons around the atom, while the negative electrons are pushing each other away and trying to fly off. As long as there are the same number of protons and electrons, the atom will be electrically neutral and will be stable.
The word for an atom that is not electrically neutral is an *ion*.
The other way atoms try to be stable is a little more…quantum-mechanics-y. The cloud of electrons around an atom is a bit like a building with several floors. You can go up and you can go down, but you can’t be halfway in between. Electrons around an atom can only stay at certain energy levels, which are like the floors in a building – they can only be at energy level 1 or energy level 2 or energy level 3, and so on, and nothing in between. No energy 1.5. What’s more, for quantum mechanics reasons that aren’t important right now, each level can only hold a certain number of electrons. Once the level is full, any electrons have to stay at a higher level.
Atoms are more stable when the highest energy level being used by electrons is completely full. For example, the first level can hold two electrons and the next level can hold eight. Helium is very stable because it has exactly two electrons, which neatly fill that first level. The next element up, lithium, is *not* very stable because it has three electrons. That’s two in the first level and one in the second level. Lithium atoms really want to get rid of that extra electron so that the highest energy level is the first and is full with two electrons. Keep going up and you have fluorine, which has nine electrons – two in level 1 and seven in level 2, *one* electron short of having a full 2nd level of eight electrons. It *really* wants to gain an extra electron and fill that last spot.
However, now the atom has a conflict between two different things going on. Looking at lithium: it would be more stable if it gets rid of the third electron and has a neatly full level 1 electron shell; but, then it would have unbalanced electrical charge because it has three protons in the nucleus. That’s why it has three electrons to begin with! How can the atom be stable when it can’t gain or lose electrons but also *needs* to gain or lose electrons?
The answer is: it shares them with other atoms. Or, it *does* get rid of them and then just hangs out next to other charged atoms. Take oxygen. It has eight electrons – two in the first shell, six in the second shell. It wants two more electrons to fill that second shell. Hydrogen has one electron, and would really like to have two. If you put an oxygen atom with two hydrogen atoms it all fits together very neatly! All of them together are electrically neutral: there are ten total protons (eight in the oxygen atom, one each in the hydrogen atoms) and ten total electrons. The oxygen atom “shares” one electron each with the hydrogen atoms, and the hydrogen atoms also share their single electrons. Now, the hydrogen atoms each have two electrons in their outer-most shell, and the oxygen atom has eight electrons in its outer-most shell. Everything is neat and stable. [Here is a diagram](https://cdn.britannica.com/04/96904-050-140D0BAE/atoms-bond-bonds-electrons-hydrogen-oxygen-atom.jpg) showing how it’s shared.
Or, consider sodium chloride, which is table salt. The sodium atom has 11 electrons – if it gives up that electron, it will have a full outer shell of eight (plus the inner shell of two). Chloride is on the other end, with 17 electrons – two in the inner shell, eight in the next shell, and seven in the last. It will be more stable if it gains an extra electron. Rather than sharing, the sodium atom just gives its electron up and chloride takes it. They are more stable as ions than they would be with their electron shells being messed up. But, now the two atoms are charged: the sodium atom has one more proton than electrons, making it positive; and the chlorine atom has one more electron, making it negative. Opposite charges attract, so the two atoms just kind of stick together like magnets.
There are different ways for atoms to connect with each other, called bonds. One kind of bond is similar to magnets sticking together, atoms with opposite charges attract each other while the same charges push each other away. Other bonds are more like Velcro, where part of each atom sort of overlaps with the other.
The many different kinds of atoms will form different kinds of bonds, and some combinations are stronger or more stable than others. Once a group of atoms forms that is very stable it will tend to stay together and act like.a single unit.
Some combinations are very big, others are really small. Some are flexible and others are not. Some combinations can form bigger combinations.
The number of combinations is so huge that everything and all properties are made up of combinations of a few kinds of atoms. Most of the world we know is made mainly of a few dozen elements, with the rest being quite rare.
It’s all about the accessories.
Different atoms think different accessories are the bomb. Depending upon their size they want the proper number of accessories to look their best.
Certain atoms are missing one or more accessories to have that proper look. Other atoms have too many accessories and look gauche.
In this case the one with the too many accessories will give its extra accessory to a neighbor who is missing the accessory. Now they both have full set of accessories. The both look good and are attracted to each other and hang out.
Sometimes one atom is missing one accessory and another atom is missing a different accessory. One may be missing a bracelet and the other may be missing a necklace. They decide to share the accessories and take turns wearing the bracelet and necklace. This way they both have a full outfit and stay close since they agreed to share the items.
Accessories are electrons. Giving gifts are ionic bonds and sharing accessories are covalent. Chemistry is the science of how elements bind by sharing and giving up electrons.
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