Spin, when applied to fundamental particles, is a property rather than a description. The basic components of matter are not tiny spinning tops, like coins that are stood on edge then flicked on opposite sides to make them rotate. Instead, spin is a physical property that can be demonstrated and also a numerical value that … Continue reading What is Spin?
What is the Strong Nuclear Force?
When thinking about atoms, one of the obvious puzzles is how a nucleus stays together when it is packed with positively charged particles (protons). Why don't the positive protons simply repel each other, causing the nucleus to disintegrate? The fact that there are also neutral particles (neutrons) in the nucleus may “dilute” the positive charge … Continue reading What is the Strong Nuclear Force?
Hideki Yukawa and Meson Theory
How does the nucleus of an atom stay together? Why don’t the positively-charged protons repel each other and cause the nucleus to disintegrate? The early models of the atom imagined solid spheres, perhaps with different sizes, shapes or “colours” distinguishing one type of atom from another. Then came J J Thomson’s discovery of the electron … Continue reading Hideki Yukawa and Meson Theory
Alpha and Beta Nuclear Decay
Radioactive decay happens when an unstable nucleus changes into the nucleus of a more stable (different) element. We know that elements are defined by the number of protons in their nucleus so the only way for an atom to change into something else is by either increasing or decreasing the number of protons that it … Continue reading Alpha and Beta Nuclear Decay
Atoms: Key Facts
There's an old science joke: "you should never trust atoms because they make up everything". And that's true. Atoms aren't liars (as far as I know) but they are the smallest parts of all substances. But what else are you expected to know? Firstly, atoms are really small. The diameter of a typical atom is … Continue reading Atoms: Key Facts
Electron Shells
The idea of electron shells is essential in chemistry and also plays an important part in various areas of physics so needs to be discussed in its own right. But before we look at electron shells let's be clear that this is just a model - a way of imagining what is going on inside … Continue reading Electron Shells
Atoms – basic ideas
The original idea of an atom came from asking a very simple question: if you take a substance and cut it into smaller and smaller pieces, is there a limit to how many times you can keep cutting it into smaller pieces? When this question was originally asked, back in ancient Greece around 400 BC, … Continue reading Atoms – basic ideas
Radioactivity: Basics and Test
This post highlights the fundamental knowledge and key skills that form the basics of radioactivity. There is also a short online test for you to check your understanding. The first things you need to know are descriptions of the atom (how models have changed with time) and what causes "radioactivity". These two fundamentals are covered … Continue reading Radioactivity: Basics and Test
Atomic Number and Atomic Mass
When you learned about the Periodic Table during KS3, you were told that it lists all the elements in order of their atomic number. You should also have learned that every element has two numbers; the smaller value is the element's atomic number and the larger value is the element's atomic mass. The value for … Continue reading Atomic Number and Atomic Mass
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