How many atoms of aluminum are on each side of the following equation: 4Al + 3O2 --> 2Al2 O32

according to law of conservation of mass given by lavoiser mass can neither be created nor be destroyed in a chemical reaction

so Al atoms on both sides should be same total al atoms are 4

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.

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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.