Neutral atoms get smaller as you move across the periodic table from (left to right) because the atom increases in electrons. The more electrons, the bigger the effective nuclear charge (electron and proton attraction) and so basically the atom shrinks.
There are usually 3 topics used to compare types of radiation:
Ionising ability
Penetrative power
Range in air
Ionising ability
Alpha radiation has strong ionising ability, while beta only has moderate ionisation and gamma is very weakly ionising.
Penetrative power
Alpha particles are weakly penetrating, stopped by paper, while beta particles have stronger penetrating ability, stopped by skin and gamma radiation is very strongly penetrating, stopped only by thick layers of lead.
Range in air
Alpha particles- range of only a few centimetres
Beta - range of up to one meter
Gamma- infinite range in air.
Hope this helps:)
Please, observe that it is not right to say that a substance content heat.
Heat is not something that a body or substance content. Heat is the transmission of energy due to difference of temperatures.
An endothermic reactions is that where the reactants abosorb energy from the surroundings to occur. The products, then, will be higher in energy than the reactants while the surroundings get colder.
