Question

An atom of gadolinium has an atomic number of 64 and a mass number of 153. How many electrons, protons, and neutrons does it contain? (Chapter 4)

Short answer

A gadolinium atom has an atomic number of 64, which means it contains 64 protons. Since it has a mass number of 153, there are 153 - 64 = 89 neutrons. In a neutral atom, the number of electrons is equal to the number of protons, so it contains 64 electrons. Therefore, a gadolinium atom contains 64 electrons, 64 protons, and 89 neutrons.

Step-by-step solution

Find the number of protons

Since the atomic number of gadolinium is given as 64, this means that there are 64 protons in one atom of gadolinium.

Find the number of neutrons

The mass number of gadolinium is given as 153. Since the mass number is equal to the sum of protons and neutrons, we can find the number of neutrons by subtracting the number of protons from the mass number. Number of neutrons = Mass number - Number of protons = 153 - 64 = 89 So, there are 89 neutrons in one atom of gadolinium.

Find the number of electrons

In a neutral atom, the number of electrons is equal to the number of protons. Therefore, there are 64 electrons in one atom of gadolinium. In conclusion, a gadolinium atom contains 64 electrons, 64 protons, and 89 neutrons.

Key concepts

Atomic Number

The atomic number is a fundamental characteristic of an element that defines its identity on the periodic table. For instance, the atomic number of gadolinium is 64, which essentially tells us that every atom of gadolinium has 64 protons in its nucleus. This number is crucial because it determines the chemical properties of an element and its place among other elements.

Protons, which are positively charged particles found in the nucleus of an atom, dictate the atomic number. The number of protons is always equal to the number of electrons in a neutral atom, ensuring that the overall charge is balanced. For students, remembering that the atomic number equals the number of protons (and electrons in a neutral atom) will help simplify many chemistry problems.

Understanding Gadolinium's Place

With an atomic number of 64, gadolinium is the 64th element on the periodic table. This indicates not only its number of protons and electrons but also gives insights into how it will react with other elements. The higher the atomic number, generally, the more complex the element's electron arrangement and chemical behavior.

Mass Number

The mass number of an element provides information regarding the total number of protons and neutrons in the atom's nucleus. Unlike the atomic number, which is uniform for all atoms of an element, the mass number can vary because an element can have different isotopes with different numbers of neutrons.

In the case of gadolinium, having a mass number of 153 means that the sum of protons and neutrons in its nucleus is 153. However, since we already know there are 64 protons (indicated by the atomic number), we can determine the number of neutrons by subtraction: 153 (mass number) - 64 (number of protons) equals 89 neutrons.

Isotopic Variations

Remember that if another atom of gadolinium had a different mass number, this would be because it has a different number of neutrons, making it an isotope of gadolinium. Mass numbers and isotopes become especially significant when looking at nuclear chemistry and understanding atomic stability.

Protons, Neutrons, and Electrons

Atoms are made up of three basic particles: protons, neutrons, and electrons. Protons (positive charge) and neutrons (no charge) are contained within the nucleus, while electrons (negative charge) orbit around the nucleus in various energy levels.

An easy way to remember this is to think of the nucleus as the 'city center' with protons and neutrons 'living' there, and electrons as 'commuters' that travel on 'roads' or energy levels around this center. The number of protons defines the element (and its atomic number), while the number of neutrons can vary, leading to different isotopes. The electrons are equal in number to the protons in a neutral atom.

Neutral Gadolinium Atom

In a neutral gadolinium atom, we therefore have 64 protons, 89 neutrons, and 64 electrons. These numbers help define the physical and chemical properties of an atom, including its atomic weight and how it will bond with other atoms. Understanding the relationship between these subatomic particles is crucial for grasping the basics of chemistry.