Isotopes, ions, fission and fusion

Understanding the composition and characteristics of an atom is fundamental to the study of physics. In this section, we will explore how atoms can change by forming ions and isotopes, or through processes such as nuclear fission and fusion.

Isotopes

Isotopes are atoms of the same element that have different numbers of neutrons but the same number of protons. This means they have different nucleon numbers (A) but the same proton number (Z).

For example:

• Carbon-12 has 6 protons and 6 neutrons.

• Carbon-14 has 6 protons and 8 neutrons.

Despite having different mass numbers, both are still carbon because they have the same number of protons.

Isotopes of an element often have similar chemical properties but different physical properties, such as different levels of radioactivity.

Ions

Atoms can gain or lose electrons to form ions, which are charged particles:

1. Positive Ion:

   • Formed when an atom loses electrons.

   • The atom becomes positively charged because it has more protons than electrons.

2. Negative Ion:

   • Formed when an atom gains electrons.

   • The atom becomes negatively charged because it has more electrons than protons.

Nuclear fission and fusion