1 - Elements and Chemical Bonds
Abstract (TL;DR):
This is an introduction to the Dance of Chemistry arc, briefly covering how atoms continue to reduce their energy and become more stable. Since noble gases are the most stable atoms in existence, atoms try to emulate them and often do so through bonding. One example of such bonding is covalent bonding, conveniently demonstrated in the animation to the left. In this particular bond, two hydrogen atoms bond to be in a state similar to helium, the nearest noble gas.
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Animation by Bevan Lynch
Welcome to the Dance of Chemistry arc. If you're following from the Elemental Flow arc, you have a perspective that many high-schoolers and even many college students don't. To put you at ease, there’s a lot less quantum mechanics in this part. In fact, many chemistry students begin learning from here. It's a solid place to begin in any of the sciences.
Remember the guy at the beginning of the Elemental Flow arc that I was telling you about? That dude that shows off by telling everyone how popular he is? We'll address him in the next section. As for now, allow me to introduce you to the atomic dance.
Society of Atoms
If you’re like those that (understandably) feel the need to be within every social circle, then you’re likely a part of 95% of the atoms. But if you’re the type to believe that being invited to parties isn’t significant in the grand schema, then you’re a noble gas.
Although all atoms are different, they all seek one thing: to be like the noble gases, which have their orbitals completely filled with electrons. They are completely content with their existence with no need for social validation. The standards that a noble gas holds puts it in a league of its own. They are the ones that host and throw the parties.
But how do other atoms get into these parties? You can’t just RSVP your way into these shindigs. What kind of invitations do they need to wield? Well, these invitations are not like conventional ones, where if you get one, you’re able to go. No, instead, atoms have to collect a certain number of invitations to be admitted into the ranks of noble gases, which can be a more difficult task.
But there’s good news! Each atom is born with a certain amount of them. According to the amount of protons they have, they attract a certain number of electrons. These electrons function as the crucial invitations to the noble gas party. So then, how do atoms get more electrons?
The answer is that atoms pool their electrons with the electrons of another compatible atom. However, this is harder than it looks. Sometimes, a compatible atom isn’t present. Sometimes, they’ll only share their electrons in certain situations. Atoms have to be very creative and what they do can seem like madness to us.
But there is order to the madness of the social dance of atoms. Amazingly, they partake in this dance for their own satisfaction. To understand what might seem crazy to us, we had to discuss orbitals as they outline which atoms can dance and how. This is the perspective which starting chemistry students lack. Starting from here is fine, but, consequentially, there is no easy way for one to understand the atom's motivations (this is your obligatory warning to go back and read through the Elemental Flow arc).
Let’s take a look at hydrogen. This atom only has one electron in normal cases. The poor atom hasn’t gotten many invitations and understands that receiving one will put it at ease.
But why only one?
Hydrogen exists in the 1s orbital. The 1s orbital is allowed two electrons, each with opposite spins. All elements desire to fill their outermost electron shell, or their valence shell. That means, in order for hydrogen to be as stable as possible, it need only one other electron.
Care to Dance?
How does hydrogen determine who to exchange electron invitations with? You can imagine that, if you, as hydrogen, wanted to be like one of the amazing noble gases, you would pick the one nearest to you in personality to emulate. It so happens that the one nearest to hydrogen is helium.
Image via ScienceNotes
Of course, that decision is in the name of energy. Noble gases have full valence shells, meaning they are more stable than atoms that do not. The reasons for this are found in the properties of each atom, explained by the quantum numbers (EF 4-5) that represent them. For example, an electron without its opposite spin will be of higher energy than an electron with its opposite spin. Also, the nucleus is positively-charged and attracts electrons. With enough electrons, the nucleus’ positivity is partially blocked by the negative charge of the electrons, and so, it is harder for it to attract any more, giving the atom a lower binding energy. That effect is called electron shielding, a term you’ll undoubtedly hear again soon.
Helium, with its two electrons for its two protons, and a full outer shell, is, indeed, something hydrogen should want to emulate. But I digress, the original query tries to get to the root of what hydrogen binds to.
Here, I would like to introduce the diatomic nature of atoms. A diatomic molecule is that which is composed of two atoms. It so happens that hydrogen exists in nature as a homonuclear diatomic molecule, meaning that it's two atoms are the same - homo- meaning “same” and “nuclear” representing nucleus.
Image by John Wiley and Sons, Inc.
This certainly fixes hydrogen’s problem doesn’t it? They each have one electron, represented by a red dot in the above image, and they are willing to share by forming a covalent bond. By combining their electrons they both satisfy each other. The best part is that they both have the necessary amount of invitations to join the noble gases at their next party.
It’s Not Always So Pleasant
Hydrogen is often used as an example to explain facets about atoms because it is the simplest atom we can use. But there are many more atoms on the periodic table. And, unfortunately, they don’t all play nice. In many cases, the introduction of another atom will disturb the whole system…like that guy who flaunts all his electrons and wants more. Let’s give him a name now: oxygen. And, just because oxygen likes to feel good about himself, we’ll make sure he gets all the attention he deserves in the next part.
As always, thank you for joining me on this new arc. Please feel free to ask any questions you have and join our new mailing list for notice on new articles.