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

In a dot and cross diagram, what do the dots represent?

1. Protons in the nucleus

2. Electrons provided by one atom

3. Shared pairs of electrons

4. Nuclei of the atoms

The correct answer is: Electrons provided by one atom

In a dot and cross diagram, the dots specifically represent the electrons that are contributed by one of the atoms involved in a chemical bond. This type of diagram visually distinguishes between the electrons from different atoms, facilitating an understanding of how they interact. The dots indicate the valence electrons from a particular atom, highlighting its role in forming bonds, whether they be ionic or covalent. For example, in a covalent bond, dots from one atom and crosses from another help show how they share electron pairs, while in ionic compounds, only the donation of electrons to another atom is represented. Understanding this is crucial for grasping concepts like electron configuration and chemical bonding, which are foundational in chemistry.