The Field Guide to Particle Physics https://pasayten.org/the-field-guide-to-particle-physics©2021 The Pasayten Institute cc by-sa-4.0The definitive resource for all data in particle physics is the Particle Data Group: https://pdg.lbl.gov.The Pasayten Institute is on a mission to build and share physics knowledge, without barriers! Get in touch.A few References and Resources for you.Isotopes of Helium:https://en.wikipedia.org/wiki/Isotopes_of_heliumHelium Fact Sheet from NIST:https://webbook.nist.gov/cgi/inchi/InChI%3D1S/HeWe've got fun details about Protons, Neutrons and the atomic nucleus on our Field Guide website.Some helpful links to ideas about nuclear binding energy:http://hyperphysics.phy-astr.gsu.edu/hbase/NucEne/nucbin.htmlhttps://en.wikipedia.org/wiki/Nuclear_binding_energy... and that famous plot.The Alpha ParticlePart 3 - Binding EnergyAt this point you might be wondering. This is all great, but helium is a chemical element. It’s a gas. What on Earth does helium have to do with particle physics?! We’re almost there. And when you see the connection, you might freak out. But let’s briefly review what we know so far.Helium is a gas trapped underground and made up of Helium atoms. Each atom has a nucleus with two protons. Almost all of the helium on Earth also has two neutrons. The chemistry of Helium is rather boring. Helium is a noble gas. It doesn’t usually form chemical bonds .The nuclear physics of Helium by comparison, is fascinating. So let’s talk about some nuclear physics.Chemistry vs Nuclear PhysicsPart of what makes Chemistry so hard to understand is the diversity of the elements. With almost 100 possibilities, the number of combinations of elements - the number of molecules - is effectively limitless. Nuclear physics, by contrast, includes only protons and neutrons. Doesn’t that feel a little more manageable?The nuclei of atoms are considerably easier to wrap your mind around. They’re super tiny globs, made up of only protons and neutrons, bound together into a ball. That’s it.Admittedly, it is weird that nuclei are so small compared to the rest of the atom. And it is weird that almost all of the atomic mass sits inside the nucleus. But at least it’s organized neatly.Of course, the insides of those individual protons and neutrons is horribly complicated. Those particles are sloppy bags of subatomic goo that are extremely difficult to describe mathematically. Because all that madness is neatly organized in those tiny packages - those protons and neutrons - we won’t worry about it here.  But we will say that all that crazy internal subnuclear goo leaves a residual “stickiness” around the edges of the particles.That residual stickiness is still pretty powerful. Pulling apart a chemical bond might cost something like 5 electron Volts of Energy - or less! Want to pull a proton off a Helium atom? That’ll cost you almost two million times as much energy.And that’s a good thing. The nucleus only has positive electric charge. It’s just protons and neutrons. If those nuclear bonds - that nuclear stickiness - weren’t so strong, they might just blow apart!The nuclear force, is seams, it’s much, much stronger than the electrical force. Nuclear physics might seem simpler to describe at first, but it is a VERY different kind of physics.Binding EnergyIt’s not really possible to go in and just pull a proton out of a nucleus. But thinking about doing that - and thinking about how much energy is required - is a good proxy for thinking about how tightly bound the nucleus is.Those protons and neutrons like to be bound together. Especially those neutrons.We call the typical amount of energy it takes to pull one of those particles off the nucleus, the binding energy.If you lined up all the different nuclei by size, you’d see a stark contrast in binding energy.On the small side, you’d see things like hydrogen: A single proton with one or two neutrons. You’d also find Helium-3 and Helium-4. Lithium and so on. Their typical binding