Question

Rounded to the nearest whole number, how many neutrons, on average, are in an atom of osmium?

Answer 1

Answer: 114

Explanation:

Osmium: It is hard, brittle transition metal.

Chemical symbol: Os

Atomic number, Z = 76

Number of protons = Atomic number = 76

Mass Number, A = 190.23 ≈ 190

Mass number = number of protons + number of neutrons

⇒190 = 76 + n

⇒n = 190 - 76

⇒n = 114

Thus, the atomic number of an atom of Osmium is 114.

Answer 2

Answer: 114

Explanation:

The mass number of an element gives the sum of the protons and the neutrons inside the nucleus of one atom of that element, while the atomic number of an element gives the number of protons inside one atom of that element.

We can infer the number of neutrons inside one atom of Osmium from its mass number and atomic number.

The atomic number of osmium is 76, so each atom of osmium has 76 protons

The (average) mass number of osmium is 190, so each atom of osmium has (on average) 190 protons+neutrons

So, in order to find the average number of neutrons, we can subtract the atomic number from the mass number:

$N=A-Z=190-76=114$