International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

Which particle would you find in the electron cloud surrounding an atom's nucleus?

1. Neutron

2. Proton

3. Electron

4. Nucleon

The correct answer is: Electron

The particle found in the electron cloud surrounding an atom's nucleus is the electron. Electrons are negatively charged subatomic particles that occupy the space around the nucleus, which is made up of protons and neutrons. The arrangement of electrons in these clouds is crucial for determining the chemical properties of an element because they are involved in bonding and chemical reactions. The electron cloud model illustrates how electrons do not have defined positions but are instead present in regions of probability, which effectively contribute to the atom's overall behavior. Protons and neutrons, on the other hand, are located within the nucleus itself, while the term nucleon refers to both protons and neutrons collectively, which again are not found in the electron cloud. Therefore, the presence of electrons in the electron cloud is a fundamental aspect of atomic structure that plays a significant role in chemistry.