What is the atomic mass of element X if 10.69 g XCl3 contains 5.55 g X?

Atomic mass of element X = 115 g/mol (Approx)

Explanation:

Given:

Amount of XCl3 = 10.69 gram

Amount of X = 5.55 gram

Find:

Atomic mass of element X

Computation:

Moles of Cl =  [Mass of Cl / Molar mass of Cl )

Moles of Cl = [(10.69 - 5.55 ) / 35.5]

Moles of Cl = 0.14479 (Approx)

Moles of X = 0.14479 / 3

Moles of X = 0.04826

Atomic mass of element X = 5.55 / 0.04826

Atomic mass of element X = 115 g/mol (Approx)

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.  

10 years is the answer