How many br atoms are in 1.98 g of br?

1.5 x 10²²atoms

Explanation:

Given parameters:

Mass of Br = 1.98g

Unknown:

Number of atoms

Solution:

A mole of a substance is the amount of substance contained in the avogadro's number of particles.

To solve this problem, we must first find the number of moles present in the given mass of the Br atom:

       Number of moles = =    = 0.025mole.

Now we know that:

       1 mole = 6.02 x 10²³

      0.025 mole = 0.025 x 6.02 x 10²³ = 1.5 x 10²²atoms

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.