Question

Mercury An isotope of mercury has 80 protons and 120 neutrons. What is the mass number of this isotope?

Short answer

The mass number of the mercury isotope with 80 protons and 120 neutrons is \(200\).

Step-by-step solution

Understand the concept of mass number

The mass number of an isotope is the total number of protons and neutrons in the nucleus of an atom. It is this mass number that distinguishes isotopes of the same element from one another. The formula to calculate the mass number is: Mass number = Number of protons + Number of neutrons In this case, we are given that the mercury isotope has 80 protons and 120 neutrons.

Apply the formula to find the mass number

Now we can apply the formula for the mass number using the given number of protons and neutrons: Mass number = Number of protons + Number of neutrons Mass number = 80 + 120

Calculate the mass number

Performing the calculation from Step 2: Mass number = 80 + 120 = 200 So, the mass number of this mercury isotope is 200.

Key concepts

Isotopes

Isotopes are versions of the same chemical element that have differing numbers of neutrons but the same number of protons in their nuclei. Although they share chemical properties, isotopes of an element have different physical properties because their mass numbers vary.

For example, carbon-12 and carbon-13 are isotopes of carbon, with mass numbers of 12 and 13, respectively. The difference in their mass numbers is due to the difference in the number of neutrons; carbon-12 has 6 neutrons, while carbon-13 has 7.

In the exercise, we encountered an isotope of mercury with 80 protons and 120 neutrons. It's crucial to note that regardless of the neutron count, the number of protons defines the identity of an element. Thus, all isotopes of mercury will have 80 protons but can have a varying mass number due to the changeable neutron count.

Protons and Neutrons

Protons and neutrons are subatomic particles residing in the nucleus of an atom and are collectively referred to as nucleons. Protons carry a positive charge, while neutrons are neutral, having no charge.

The number of protons, also known as the atomic number, characterizes the type of element. For example, every atom of mercury has exactly 80 protons. Neutrons play a crucial role in providing stability to the nucleus and can vary in number among isotopes of the same element.

Understanding protons and neutrons helps to explain why atoms of the same element can have different atomic masses, leading to the existence of isotopes. The exercise highlights that for the particular mercury isotope in question, there are precisely 120 neutrons. This neutron count, in combination with the proton count, helps us calculate the mass number.

Atomic Structure

Atomic structure refers to the arrangement of subatomic particles within an atom. At the center is the atom's nucleus, made up of protons and neutrons. Orbiting around the nucleus are electrons, which are negatively charged.

The atomic structure determines the element's properties and behavior in chemical reactions. Protons define the element's identity, neutrons contribute to the atomic weight and affect isotopic stability, and electrons determine how an atom interacts with others to form compounds.

In the context of our exercise, it is the nucleus of the mercury isotope that we're focusing on, as the mass number relates specifically to the number of protons and neutrons in the nucleus. The atomic structure plays a pivotal role in understanding how and why the mass number is used to differentiate isotopes of the same element.