Changes of State are Energy Changes
If you have read any of my blogs on energy it should be clear that particles are nodes of energy that proactively react to the energies of their environment. Changes of state are all about particles rearranging themselves in more energy efficient ways so as to effectively process the energies of a changed environment.
In the depths of winter photon energies from the sun and therefore passing between earth objects are reduced. The electrons in water that supply nuclear particles energy move marginally closer to those nucleons making the water somewhat less fluid. A minor movement or impurity triggers a change in which the water particles start assembling into the more rigid structure that is ice and which in the changed environment will more efficiently meet the energy needs of the particles.
Changes to the more efficient ice structure release photon energies. Ice is an unusual solid because although its molecules are denser than those of water the way they link together is more space consuming. It is why solid ice floats on water.
Input photon energy into its environment and ice will melt back to a water structure that can better and more efficiently accommodate the increased energy. Add more energy and that water will eventually turn to its steam vapour form. The level sections in the diagram are where energy is being either added to or removed from the changing structure without increase in temperature. But what is temperature? A thermometer cannot enter a solid structure or into the molecules of a liquid or gas structure. It gets a measure of the photon energies outside of a solid or passing between fluid molecules.
Changes of state occur so as to better accommodate more or less energy. Particles move significantly further apart or closer together in state changes. Such movements enable structures to better accommodate higher or lower mass energies whilst keeping photon energies between particles (temperature) steady. Looser energy ties between liquid molecules and even looser energy links between gas molecules are why a hand movement can part them but not solids.
Unlike chemical and nuclear changes, state changes do not involve losses and gains of particles by other structures.
Chemical changes are energy changes.
As with state change, chemical change is all about particles reacting to the energies of their surround environment, forming structures that more efficiently satisfy their energy desires in that environment. It is the fundamental reason why chemical changes occur, yet it rarely gets a mention in any teaching of chemistry.
In chemistry we learn about electrons, protons and neutrons and of their arrangements in atomic elements, molecules, mixtures and compounds. We discover ions, isotopes and covalent, ionic and metallic bonds. We are introduced to chemical equations and learn how to balance them in terms of atoms, volumes and masses. But all of these things are about energy and how it behaves.
Ask why hydrogen and oxygen exist as the molecules H2 and O2 we are told they are more stable. But what is this stability? It is the result of particles coming together in more energy efficient, energy exchanging structures.
There is less mass or total energy (node energy plus photon energy) in the molecules than in the two separated atoms. Atom particles will combine as a molecule when together they satisfy their energy desires more efficiently.
For some reason particles pro actively desire energy and want to get it in the most efficient way. Such desires for energy are the reason for light speed photon energy flows and the associated particle energy absorptions and emissions. Those same desires are what hold the particles of a structure at a distance and cause them to vibrate.
Water H2O is a more energy efficient combination of hydrogen and oxygen. We use this fact in fuel cells to harvest electrical energy. Simply bringing oxygen and hydrogen together in the right proportions in a container will not of itself create water and release energy because the molecules in the mixture are content with their energy interactions. However, if we input a spark of photon energy we upset that particle contentment and some re-combine as water, releasing photon energy. That photon energy further upsets the contentment and a rapid explosive energy releasing change to water ensues.
The burning of paper, wood, domestic gas and fuel in car engines are other examples where an activation energy is required to trigger chemical changes that release heat in the process of forming more energy efficient structures of particles. Chemistry is an extensive subject but I hope in giving you the above few examples I have started to persuaded you that chemistry is really a science of preferred energy formations. We will return to this later but now let us consider changes of state.
Temperature and heat content are clearly not related. Particle structures vary considerably and with it their ability to accommodate thermal energies when at the same temperature. Look up and compare the specific heat and thermal conductivity for several different material structures and you will see that some structures are far better than others at holding heat and some are better at conducting heat. Compare hot sand with cold sea or observe how some oven feel hotter than others.
It might appear that the flow of thermal energy along a structure is temperature driven from hot to cold but that is not how it is. The “hot” particles emit more than “cold” ones and “cold ones” absorb more than “hot” ones so that heat is dissipated in a hot to cold direction rather than temperature driven. We might, for example view the sun as being all energy output and no energy input, but its particle desires that pull photons from space into it maintain its spherical shape. Moreover the desires of its core particles deliver and control its mass energy releasing fusion process. Similarly the gravity desires of earth’s core particles contribute to the heat at its centre.
In chemistry it is not uncommon now to be introduced to reactivity diagrams like that shown for metals. The diagram enables us to say that iron added to copper sulphate will replace the copper and make for iron sulphate and that magnesium added to zinc chloride will replace the zinc and create magnesium chloride. The diagram also enables us to say that the reverse reactions will not naturally occur.
Rarely are we told why the reactivity series works. It works because the particles of some metals in combining with the particles of water, acids and oxygen make more energy efficient structures than others metals do. The iron displaced copper and magnesium displaced zinc in the above examples because in doing so they made for more energy efficient structures. They released photon energies in the process.
Try not to be confused by the term binding energy much used to explain the stability of a structure. The word binding makes it sound like it is an energy within the structure but that is just not so. The binding energy is the external energy we have to input to break its bonds. More stable, more energy efficient structures need greater inputs of binding energy to break their particle bonds. The reversal of many chemical reactions, like that when we charge a battery, requires input energies to break and rearrange particle bonds in a way that accommodates the increased energy.
In all chemical changes the least attached outer valence electrons play a major role. That is because they are more sensitive to the energy desires of surround structure protons. If it is more energy efficient to do so they will transfer their allegiance in full or in part to surround structures and thereby form bonds with them. Of course any such changes also brings a rearrangement of associated electrons and nuclei.
The groups and periods of the periodic table of elements tell us much about the distribution of energy gathering electrons around the nucleus of each element. The table groups tell us how many electrons are in the outer valence shell. As the inert gases of group 8 are most energy stable we can conclude that outer shells of 8 electrons are desired.
The transition metals that occupy the large section in the middle all have, along with the alkali earth metals, two valence electrons in their outer shell. We should not be surprised that they have many things in common. One thing they have in common is they will readily combine with the atoms of non metals in group 6. It is a way of securing a more energy efficient particle structure arrangement with 8 outer electrons. Similarly the alkali metals of group 1 will willingly combine with the halogens of group 7 .
Chemistry is a science that is all about energy formations.