I wonder what made you pick sodium and polonium as the two elements you wanted to ask about. Before we talk about your specific question, I want to talk about chemical reactions in general.

You probably know that everything is made up of molecules and that molecules are made up of atoms which are "stuck together" with what is called a chemical bond. An example is water, which is made from two hydrogen atoms and one oxygen atom. You probably also know that atoms have a nucleus which is very, very tiny and that, surrounding the nucleus, there are particles called electrons. It turns out that the kind of bonds that an atom can form are completely determined by the number of electrons that surround each atom.

One thing that can happen is that an atom can give up an electron. Since the nucleus of an atom is positively charged and every electron is negatively charged, when an atom gives up an electron, it becomes positively charged. Sodium is an atom which can give up a single electron. Another thing that can happen is that an atom can accept an extra electron, which makes it negatively charged. Chlorine is an atom which can accept a single electron.

So when you combine chlorine and sodium, the sodium atoms become positively charged and the chlorine atoms become negatively charged -- and since opposite charges attract, the sodium and chlorine atoms attract each other. This kind of bond is called an ionic bond. You may have heard of what you get when you combine sodium and chlorine...you get table salt.

There are other kinds of chemical bonds. Another important kind of bond is a "covalent bond" in which atoms share electrons. This comes up a lot in the study of the chemistry of living things. Another thing you should know about chemical bonds is that some atoms form bonds more easily than others and that some bonds take energy to form and some give up energy when they are formed. For example, when you combine hydrogen and oxygen to make water, there is a lot of energy released (in the form of an explosion!).

What I have explained to you is a big subject and there is a lot of stuff to know, but the amazing thing is that all of these complications come from a few simple objects: atoms and electrons. If you understand atoms and electrons then the understanding how chemistry works will be much easier.

Now onto sodium and polonium. Polonium is an element which is extremely radioactive and most of the information I could find about it involve radioactivity. I did manage to find a little about out about some of the molecules that polonium can form. It would seem that polonium can accept two electrons and that a single polonium atom can combine with two sodium atoms to make sodium polonide. Unfortunately, that's all I've been able to find out about combining sodium and polonium.