The MRI machine uses liquid helium to cool its powerful magnets ... it is a tiny little atom even by atomic standards. It also expands about 750 times when it turns into a gas, according to ...

The atom is neutral as it has two positive protons and two negative electrons. A helium atom that has lost or gained an electron is an ion. The ion has two positive protons but one electron so it ...

For example, a helium atom has an atomic mass of 4 ... especially those of Frederic and Irene Joliot-Curie. They used a different method for tracking particle radiation. Chadwick repeated their ...