What is it about, let’s say arsenic atoms, that makes it so much more deadly than gold for example. And please expand this to molecules too.
In: Chemistry
>What’s the actual difference between different atoms besides just some protons, neutrons and electrons?
Well only one – electron configuration.
Electrons arrange themselves in shells or orbits around the nucleus. As the atomic number increases, one by one electrons keep adding to a shell. Once a shell is full, new electrons start filling up a new shell. If you are in 11th grade, you should know that the first shell can accommodate 2. the 2nd can accommodate 8, the 3rd shell can accommodate 18 electrons and so on..
Here’s where we reach the concept of ‘valency’ or ‘valence electrons’. Generally, for an atom to be most stable, it needs a fully filled outer shell. An atom will do anything in it’s power to achieve a fully filled outer shell.
Let’s take 2 examples – An alkali metal Sodium (Na) and a Halogen Chlorine (Cl). Alkali metals are the atoms which have 1 electron in their outermost shell and halogens are those atoms who are just one electron short of filling their outermost shell. Now when given an opportunity to lose that extra electron, Sodium will VERY readily do so so that the outermost 1 electron is gone and the 2nd last shell now becomes it’s outermost shell and the Sodium ion is now very stable. That’s why alkali metals are very reactive and we are advised to not touch them bare-skinned, unlike copper or iron or gold.
Similarly halogens just need 1 atom to fill their outermost shell completely and achieve atomic ‘Nirvana’. So they readily react with anything they can pull an electron from. And that’s why Flourine, Chlorine are dangerous gases which we are told not to inhale.
Now what about an atom that already has a fully filled outermost shell? Well they are extremely non-reactive and are called ‘inert’ gases for that very reason. Argon, Neon, Xenon, etc are used to fill up cavities where the inner materials are susceptible to reactions. Hence many bulbs come filled with inert cases and we have ‘neon lights’ because the Neon wont react with the metal filament inside (or any other part for that matter).
**TLDR: The farther away you are from achieving an outermost filled shell, the less reactive the atom is going to be.. generally. Ofcourse it’s not that simple because once you start to delve into it, you learn about orbitals and hybridisation and what not which makes the matter more complex, but I hope you get the gist of it – it’s all about how the electrons are arranged in the atom.**
Latest Answers