Foundational chemistry ideas needed to understand metals
If you want to have a deeper understanding of metals you need to have an understanding of some foundational chemistry and physics concepts. If you already have this background you might as well skip on to the next article in this series as this is just as bit of background to help anyone who wants to learn get a quick overview of the topics they will need to learn more about.
Each atom contains a nucleus with a positive charge and a number of electrons that orbit that atom.
Inside the nucleus there's a collection of elementary particles that together form the "core" of the atom so to speak. There are positively charged protons and there's neutral charged neutrons.
The periodic table is a way of organizing the elements into groups that share some properties. This way of organizing elements is powerful for a number of reasons. There was even as case of an element that was predicted to exist by the periodic table that was found as a result of looking for such an element with the predicted properties of an element to be found there.
We name atoms based on the number of protons that they have in them. The lightest element hydrogen, is also the simplest, it has one proton and one electron that orbits it.
How many protons exist in the nucleus of the atom is a crucial aspect as to the very nature of these atoms. In a very fundamental sense protons are completely fungible, each one is the same as others. Protons are very much the original base commodity, the commodity which underpins all commodities.
The number of protons in the nucleus creates an electrical charge and this is balanced out by the electrons that orbit around that nucleus. Electron orbits form various group structures that are related to the amount of energy and the electrical charge. These orbits are not like satellites orbiting the earth, if they were electrons would do things like emit radiation constantly or crash into the nucleus. But seeing as these things empirically don't actually happen often1 it created one of the long standing questions in chemistry and physics as to why this doesn't actually happen. It took a long time for the smartest people in the world to figure out what was going on and this led to the creation of quantum physics as a theory to explain what was actually happening. If you really want to know how all these things work on the smallest of scales you'll have to look at quantum physics. Thankfully however on larger scales the rules of classical physics, the rules that more closely approximate the intuitions we form in our day to day lives, are close enough to accurate to cover all we need to do.
Individual elements are the building blocks of all chemical compounds. In each nucleus the number of protons forms an electrical charge that leads to attracting orbiting electrons. If the individual elements are the building blocks the connections between these building blocks are done by the way in which electrons interact. Chemical interactions are the interactions that form as a result of various atoms interacting. The exchange of electrons between atoms creates many of the fundamental processes of chemistry and physics. When a group of atoms comes together in some form we call this a molecule.
Chemical compounds are groupings of various atoms from various elements that are connected together via various means.
The air that we breathe in the atmosphere is approximately 78% Nitrogen 21% Oxygen 1% of other gasses including Argon.
The air gives a good example of how some chemicals come together in a gas. The nitrogen exists in a molecular form, Nitrogen atoms form pairs of two, which we represent in the chemical notation as \(N_2\). In this notation the \(N\) represents the element Nitrogen and the 2 is a number that's a count of how many of those atoms are together. Oxygen similarly forms pairs which we represent as \(O_2\)2. These groupings of two atoms we call diatomic. Argon atoms in the atmosphere however behave differently, those atoms are just solitary, and the notation for this is just \(Ag\).
Another especially common thing in our day to day life, and is what makes our lives possible in the first place, is water. Water is a molecule with 2 hydrogen atoms and one oxygen atom. When we write this out with chemical formula notation we get \(H_2O\). "Water" is the name of the liquid state of \(H_2O\) at standard temperature and pressure.
Other materials have other ways in which various atoms come together. For example in a metal you have a bunch of atoms that share electrons with other atoms nearby to them in the lattice structure. This is what allows metals to have many of the properties that they have like conductivity. More on what a metal is precisely in the next article
Gasses, liquids and solids
Depending on how easily the molecules can move will determine what state they are in.
When the molecules are moving very freely they are in a gaseous state. When they can't move they form a solid state. In between these two are liquids. Ice, clouds and water are all \(H_2O\) but are in different states.
Some other things we see on a day to day basis we typically only see in one state. For example the sort of table salt we see on a kitchen table \(NaCl\) is something we typically only encounter in its solid state. But given enough heat it can be turned into a liquid.
Likewise the metal that we might see in the salt shaker container is something in our day to day lives that we only see in its solid shape. However in the process of producing this the metal would have had to have been heated enough to be turned into a liquid that could be poured into a specifically salt-shaker like mould.
Despite things changing from one form to another based on the temperature and pressure they are under the atoms in them remain the same. This is part of an important concept in chemistry. If we heat things or cool things the same number of atoms exists before as after, but the amount of energy is different. Atoms are conserved in chemical reactions. This means that the inputs to a chemical reaction must be found in the outputs. Before a reaction we have the same number of atoms as afterwards, however energy can be released in such a reaction or can be required to make the action happen.
An example of energy being released in a reaction is when you burn petrol in a car. In this reaction a lot of energy is released. This energy then powers the car. We call this an exothermic reaction, a reaction where energy is released.
An example of a reaction where energy has to be added is found in those instant ice packs. The way in which this works is that energy from outside is used by the chemical reaction. This is known as an endothermic reaction.
If you look at the probability function for the position of the electron you will find that it's actually non-zero at the position of the nucleus. This leads to a situation where a proton can capture an electron via an exchange of a \(W^+\) boson and this leads to a process that creates a neutron and an electron neutrino. There's a bunch of mathematics here if you want to look at the details. ↩
There are other forms of Oxygen in the atmosphere as well, groupings of three oxygen atoms (\(O_3\)) into a molecule is known as Ozone, but these molecules exist in far smaller trace quantities. At high concentrations Ozone is unstable and it decays into regular diatomic oxygen. ↩
This post is part 2 of the "Metals" series: