What is the symbol for sodium?

Explanation:

The chemical element sodium has the atomic number 11 and the symbol Na, which is why the joke "Do you know any sodium jokes?" is so popular. Na.” Sodium was first isolated in 1807 by Humphry Davy during the electrolysis of sodium hydroxide. It is a soft, silvery white, and highly reactive metal.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.