Question

a. What are isotopes? b. How are the isotopes of a particular element alike? c. How are they different?

Short answer

Isotopes are atoms of the same element with different numbers of neutrons. They have the same chemical properties but may differ in physical properties like atomic mass and stability.

Step-by-step solution

- Define Isotopes

Isotopes are atoms of the same chemical element that have the same number of protons but differ in the number of neutrons in their nuclei. This means they have the same atomic number but different mass numbers.

- Alike Characteristics of Isotopes

Isotopes of a particular element are alike because they have the same number of protons, which determines the chemical properties and the element’s identity. This means they exhibit similar chemical behavior.

- Different Characteristics of Isotopes

Isotopes of an element differ in their number of neutrons, which leads to differences in their atomic mass. This variation in mass can result in differences in physical properties, such as density and stability. Some isotopes can be radioactive, while others are stable.

Key concepts

atomic number

To understand isotopes, it's essential to grasp the concept of the atomic number first. The atomic number of an element is the number of protons in the nucleus of an atom. Protons are positively charged particles found in the core of an atom.
The atomic number determines the identity of the element. For example, all atoms with 6 protons are carbon atoms. The atomic number is unique to each element and is a fundamental property that defines the type of element.
Hence, if two atoms have the same atomic number, they are atoms of the same element. This directly ties to how isotopes are identified. Even if isotopes have different neutron counts, they share the same atomic number, thereby making them the same element. The atomic number is often denoted by the symbol Z.

mass number

The mass number is another crucial concept when studying isotopes. The mass number is the total number of protons and neutrons in an atom’s nucleus. The mass number is represented by the symbol A.
While the atomic number (Z) counts only the protons, the mass number (A) is the sum of protons and neutrons since these particles significantly contribute to the atom's mass.
For example, if an atom has 6 protons and 7 neutrons, its mass number is 13. Even though isotopes of an element have the same number of protons (same atomic number, Z), they have different mass numbers due to the variation in the number of neutrons. This distinction in mass number helps differentiate isotopes of the same element.

neutrons

Neutrons are neutral particles found in an atom’s nucleus, alongside protons. They do not carry any charge but contribute significantly to the atomic mass. The number of neutrons can vary even within atoms of the same element, leading to the formation of isotopes.
For instance, carbon has isotopes like Carbon-12 and Carbon-14. Both have 6 protons (same atomic number) but differ in the number of neutrons: Carbon-12 has 6 neutrons, while Carbon-14 has 8 neutrons.
The presence of different numbers of neutrons among isotopes can impact physical properties such as density and stability. Some isotopes might be unstable and radioactive, leading to natural decay over time. Understanding the role of neutrons is key to differentiating between various isotopes of an element.