Area of a sphere – Volume of a sphere
This is a sphere. A sphere is a three-dimensional circle. Or you could say that a sphere is the set of all the points that are at the same distance from the center [...]
This is a sphere. A sphere is a three-dimensional circle. Or you could say that a sphere is the set of all the points that are at the same distance from the center [...]
Diagram of a uranium atom Uranium is a rare atom, not just on Earth but also in space and on other planets. There is not very much uranium anywhere. That's [...]
Diagram of a sulphur atom Sulphur atoms fall near the middle of the scale: they are heavier than silicon but lighter than iron. Every atom of sulphur has 16 protons [...]
Diagram of an iron atom The protons inside the nucleus of an atom all have a positive electrical charge, so they push away from each other. But the strong nuclear [...]
Diagram of a sodium atom Sodium is an atom that has 11 protons and 12 neutrons in its nucleus and 11 electrons circling around its nucleus. Like other light atoms [...]
Autzen Stadium, in Eugene Oregon, seats 54,000 people A proton is a tiny particle, smaller than an atom. Protons are too small to see, even with an electron microscope, but [...]
Diagram of a phosphorus atom Phosphorus atoms have fifteen protons and sixteen neutrons, so they're just a little lighter than sulphur atoms, in the middle of the range for atoms. [...]
Diagram of an oxygen atom When a star has changed all of its hydrogen atoms into helium, it turns into a red giant and moves on to convert the helium atoms into [...]
A neutron star (from NASA) A neutron is a tiny particle like a proton, smaller than an atom. Like protons, neutrons are too small to see, even with an electron [...]
Protein molecules - each dot is one molecule. What is a molecule? A molecule is a group of two or more atoms that stick together. Molecules (MOLL-uh-cyools) are so small [...]