Atomic radius and electrons because opposite charges attract, and more protons creates a stronger charge. The greater attraction draws the electrons closer to the protons, decreasing the size of the particle. Therefore, atomic radius decreases. Down the groups, atomic radius increases. This is because there are more energy levels and therefore a greater distance between protons and electrons. In addition, electron shielding causes attraction to decrease, so remaining electrons can go farther away from the positively charged nucleus. Therefore, size (atomic radius) increases. The following table summarizes the main phenomena that influence the atomic radius of an element: The electrons in the
Alpha particle less likely to be referred to as "alpha particles". The best-known source of alpha particles is alpha decay of heavier (> 106 u atomic weight) atoms. When an atom emits an alpha particle in alpha decay, the atom's mass number decreases by four due to the loss of the four nucleons in the alpha particle. The atomic number of the atom goes down by exactly two, as a result of the loss of two protons – the atom becomes a new element. Examples of this sort of nuclear transmutation are when uranium becomes thorium, or radium becomes radon gas, due