Refer to your periodic table: Which of the following has the smallest atomic radius?

Bromine

Astatine

Iodine

Fluorine

iondine

Explanation:

bromine has 185pm, astatine haa 200, iondine has 140 and lastly fluorine has 147. so iondine has the smallest atomic radius

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.