Atom represents itself that smallest particle of substance which is the carrier of its chemical properties. It can be presented in the simplified form as microscopic model of the Solar system where the role of the Sun is played by the atomic nucleus consisting of protons and neutrons (except for hydrogen which kernel is the one and only proton), and a role of planets – the electrons rotating around this kernel. That is "border" of atom is the orbit of its external electron. And whether it is possible to determine atom radius?
Instruction
1. For simplification of the decision present that atom has spherical shape. That is its external electron rotates around a kernel on a circular orbit (that in reality happens not always).
2. Then take Mendeleyev's Table to determine the molar mass of an element which radius of atom interests us. Designate it by letter m, for example. Remember that molar weight is expressed in grams on mol, that is specifies, how much? grams of substance contains in one its pier.
3. Then you should remember definition asking also its communication with universal number of Avogadro which is approximately equal 6.022*10 in degree 23. In other words, that molar mass of m determined by Mendeleyev's Table contains 6.022*10 in degree of 23 atoms of this substance.
4. Then you need to learn its density. For this purpose use any chemical or technical reference book. Designate density by a letter ρ, for example. And for what you should have learned this parameter? Knowing density ρ, knowing the molar mass of m, you in one action will find what volume of v occupies one mol of this substance on the following formula v=m/ρ.
5. Well, and for what you should know the volume occupied by one mole of a substance? Knowing what volume contains that number of Avogadro of atoms of this substance, you just like that will consider what volume occupies one atom (having strictly spherical shape). In other words, the volume of one atom is equal to m/6.022*10 in degree 23ρ.
6. Considering what a sphere volume formula - 4πRв degrees 3/3, you just like that calculate what this radius is equal to. Transforming equality, you receive the following decision: R in degree 3 = 3m/4πρх6.022*10 in degree 23
7. Take a cubic root from the received result, and here it is the required radius of atom!