# What are chemical bonds made of, and how do they form? [duplicate]

All atoms are linked together by chemical bonds, but what are the bonds themselves made of? I'm sorry that's a stupid question, but I'm only 14, and haven't entered high school yet, and my science class isn't really teaching me much I haven't learned. So please try to simplify your answer too.

• In a nutshell chemical bonds are how atoms share electrons. – MaxW May 14 at 18:33
• @MaxW I know that, but what are the connections made of? Electrons? And if so, how are they attracted to each other? – Sovereign Inquiry May 14 at 18:41
• A bond is an abstract concept meant to capture how atoms stay locked together. Behind the scenes, it's just quantum mechanics applied to electrostatic interactions. – Zhe May 14 at 18:48
• Of course there is an answer, but it contains a whole first year of school chemistry. We cannot condense it to sth you can inhale in half an hour. ;-) – Karl May 14 at 18:55
• In chemistry there aren't any "particles" in an atom other than protons, neutrons and electrons. The protons and neurons are in the nucleus. A nucleus is always positively charged so two bare nuclei would repel each other. To make molecules atoms must share electrons in some manner. To start learning about how atoms share electrons read Wikipedia's simple article Chemical bond, then the more detailed article Chemical bond. – MaxW May 14 at 19:09

## 2 Answers

I'll assume that you know that charges of opposite sign attract each other and charges of like sign repel each other. Every atom consists of a tiny, positively charged nucleus and one or more negatively charged electrons (such that the overall charge is balanced to neutral).

Let us talk through what happens when two hydrogen atoms come close to each other. The (single) electron of the first atom will be attracted to its "own" nucleus, but it will also be attracted to the second nucleus. The same happens vice versa. However, there is also repulsion between the electrons. It turns out, due to fundamental properties of the electrons (they are smeared out over space, you may have heard that in some experiments, they are like a wave), the repulsion between the electrons is a little less than their attraction to the nuclei. There is also nucleus-nucleus repulsion, but they are not that close.

Overall, it is a balance. When the distance between the nuclei becomes too short (the bond becomes too short), the repulsion between the nuclei will increase and the electrons will be pushed into too small a space, also leading to more repulsion between them. When the nucleus-nucleus distance becomes too large, the nuclei-electron attraction will become a little less, but the repulsive forces far more so, leading to a net attraction, which pulls the bond back together.

Of course, it is more complicated than what I have written here. In reality, electrons are indistinguishable from each other and do not really belong to a particular nucleus. In order to understand why hydrogen and hydrogen form a chemical bond, but helium and helium do not, some quantum physics (or at least results thereof) must become involved.

• Thank you for the simple but well-explained answer. – Sovereign Inquiry May 14 at 18:57
• I think you'd do better to talk about two main types of bonds. Use NaCl for ionic bond and H2 for covalent bond. – MaxW May 14 at 19:12
• @MaxW I really wanted to do without the octet rule, which I would have to grab out of thin air. – TAR86 May 14 at 19:14
• I don't mean to go that far down the rabbit hole. Just that sodium cations and chloride anions attract because of electrostatic force + to -, whereas in H2 the atoms share the electrons equally. – MaxW May 14 at 19:58

You may also consider an image I read once in a book that makes science accessible to the general public. It starts from the idea that electrons have a property called spin that corresponds to male or female behavior : electrons try to make pairs if they are alone. If half of the electrons are male and half female, there are two sorts of Hydrogen atoms, one half with male and one half with female properties. So if you send one million H atoms in a close container, they will collide randomly and repel each other. When two male or two female electrons collide, nothing happens. But if a male and a female electron collide, they may repel one another because of their charge, but they tend to stay together. Each electron accepts the presence of the other electron in the same region of space. They will never get completely separated in the future. This makes a bond between the two H atoms : they will stay together, and form a molecule. At the end, all $$\ce{H}$$ atoms are engaged in molecules $$\ce{H2}$$. Of course it is an image.

I perfectly know that this image does not correspond to the reality. Electrons have no sex. But they have a spin which may be either up or down. In a chemical bond, there are two electrons, and the two electrons have opposite spins. So if you replace the notion of sex by the notion of spin, it can help you understand and see how a chemical bond is made. Images are often useful when newcomers are approaching new concepts, even if everybody knows that this image is a little bit ridiculous. It may help. I even would be pleased to know our young boy's opinion.