Reddit reviews Principles of Modern Chemistry

This is a great list but for mathematics, I would add sections on geometry somewhere before calculus and maybe also discrete math. Use the UCSMP Precalculus books for sets/logic, basic algebra, trigonometry, and discrete math. Alternatively, use Paul's Online Math Notes to learn everything you want about math.

If you can afford it, you'll benefit tremendously by trying to follow the Art of Problem Solving curriculum located under "Using AoPS as a Primary Curriculum". Start from prealgebra and work your way up from there. Use [Khan Academy] as mentioned previously (https://www.khanacademy.org) to supplement. Optional: Read Art of Problem Solving, Volumes 1 and 2. Only do this if you want to get really good at math

When you're ready to move on from math, you'll need the links to The Feynman Lectures on Physics, Volumes I-III to complete your physics education. Try to find a copy of Schaum's Outline of Physics for Engineering and Science in a bookstore or read an old edition online. If you decided not to do calculus, use the Outlines of College Physics instead. Do as many problems as you can to truly solidify your physics knowledge. After doing physics, find a good chemistry textbook and read the entire thing. If you want to learn even more advanced chemistry, read this. The key to learning math and science is to do lot of problems.

I wrote this as a note to myself as well. But I hope it can help you too. If you can pirate textbooks, do it. Try to not move on to one science without being well established in the field listed before it. Good luck and feel free to PM me if you want to converse with someone who is trying to follow a similar path as the one listed here.

edit: typo

Just pick up an older edition of a well-reviewed genchem text. For example, the sub suggests the seventh edition of Principles of Modern Chemistry, available for under $40, but the sixth is available for is little as $5. If you want something free and easy, I believe khanacademy usually gets reviewed pretty well, although I prefer find it to be too slow, especially for review.

Basically, all sorts of things happen because the atoms, molecules, or whatever, want to be stable, i.e to achieve lowest energy. Forming ions, i.e. removing or adding electrons to the atom, is a way for atoms to achieve lowest energy (stable).

The spdf orbitals do come into play. An atom's electronic configuration can be described with its shells, orbitals, and the number of electrons in the orbitals. For example, iron's configuration is 1s^2 2s^2 2p^6 3s^2 3p^6 3d^6 4s^2 . The electrons has another property, its spin. Spin is an intrinsic form of angular momentum, thus carries energy. Electron can spin two way (that is the up and down arrow you see in orbitals). Pauli exclusion principle says that there cannot be two electrons in a single orbital that have the same spin (since the momemtum is the same direction, it will add up and increase energy). For the similar reason, the pairings of all electrons in a degenerate orbital (i.e. 2p, 3p, 3d, etc. orbitals with the same energy) decreases the energy (cancelled out spins in a way). However, the pairing of electron also increases energy because it decreases the distance between electrons. So, the degenerate orbitals is more stable when it is half filled or fully filled (the latter is more stable). The orbital can be more stable: just don't have the orbital. The energy of an atom is lowered when a specific set of degenerate atomic orbitals is empty, fully filled, or half filled.

Now consider the iron atom again. When it ionizes, it will want to be mroe stable. An obvious option is to take off 4s orbital entirely, losing 2 electrons, thus creating Fe^2+ . Now the ion's configuration is 1s^2 2s^2 2p^6 3s^2 3p^6 3d^6 . To become more stable, we can make 3d orbitals (take ten electrons at most) half-filled to 1s^2 2s^2 2p^6 3s^2 3p^6 3d^5 . Compared to the neutral atom, the ion loses three electrons, making it Fe^3+ . But the energy difference between Fe^2+ and Fe^3+ is not that big. External energy and chemical environment can convert them to each other. For example, oxidizing agents, a category of chemicals that love to rob electrons from others, can make Fe^2+ become Fe^3+ by accepting an electron from Fe^2+ .

Are they structurally different? Yes, other than the configuration difference (I think it can count as structure), the atomic radius is different. Fe^3+ is smaller because it has fewer electrons obviously, meaning less repulision between them, and thus stronger attraction to the nucleus.

Textbooks include the one given in the sidebar by Oxtoby and Chang's one. You may be able to find these books in your local post-secondary library. The edition doesn't matter. Oxtoby is a little hard, but it is good for in depth explanation. Chang is great for AP and other high school studnets.