eli5 Why do different elements and compounds have seemingly random properties?

Question

I don’t know if I’m asking the right question, but I feel like the smallest change in the chemical composition of something will result in a change that’s entirely unpredictable. It feels like there is no clear pattern in properties as you move down the periodic table.

In: Chemistry

Answer 1

I mean that’s fair. The thing that affects chemical properties has a lot to do with the shape and structure of the elements electrons. And since that shape doesn’t change smoothly, it jumps from one shape to another, the properties of the elements can change abruptly. The technical reason has to do with electrons only forming orbitals in what amount to standing waves. Think of it like a vibrating guitar string. If you pluck it you can get waves that are whole divisions of the strings length. One node, two nodes, etc. You can’t get 1.5 nodes though.

Let’s think of it in terms of simple geometry patterns. Imagine you have a triangle. Add one side and you get a square. You can build a pattern out of either sticking one side of a triangle to another, or sticking the sides of squares together. Despite the difference only being one side the patterns are completely different. And if you combine say triangles AND squares it’s another completely different pattern. This is sort of like moving sideways on the periodic table, where the outer shell of electrons has different numbers of electrons.

Similar if you just change the size even with the same number of side. A big square pattern, will look similar to small square patterns. This would be similar to moving vertically in the periodic table (ish. This is a metaphor). But if you mix big squares and small squares you no longer get nice even square patterns because the sizes don’t match.

Also add onto that that the temperatures and pressures that we live at which are the ones that readily support the complex processes needed for life are in a fairly narrow range compared to the universe at large. Like pretty much any molecule if you throw it into the sun is just going to turn into plasma all the same.