Study Notes
Atoms are composed of three sub-atomic particles: protons, neutrons, and electrons. Protons and neutrons are located in the nucleus, while electrons orbit in shells around the nucleus.
- Proton — a subatomic particle with a positive charge and a relative mass of 1.
Example: Found in the nucleus of an atom. - Neutron — a subatomic particle with no charge and a relative mass of 1.
Example: Also found in the nucleus of an atom. - Electron — a subatomic particle with a negative charge and a negligible mass.
Example: Orbits the nucleus in shells. - Nucleus — the central part of an atom containing protons and neutrons.
Example: The nucleus is much smaller than the atom itself. - Electronic Configuration — the arrangement of electrons in an atom's shells.
Example: Magnesium has an electronic configuration of 2,8,2.
Exam Tips
Key Definitions to Remember
- Proton: Positively charged particle in the nucleus
- Neutron: Neutral particle in the nucleus
- Electron: Negatively charged particle orbiting the nucleus
- Nucleus: Center of the atom containing protons and neutrons
- Electronic Configuration: Arrangement of electrons in shells
Common Confusions
- Confusing the charge of protons and electrons
- Misunderstanding the size of the nucleus compared to the atom
Typical Exam Questions
- What is the charge of a proton?
Positive (+1) - How are electrons arranged in an atom?
In shells around the nucleus - What did Rutherford's gold foil experiment demonstrate?
That atoms have a small, dense nucleus
What Examiners Usually Test
- Understanding of the nuclear model of the atom
- Ability to describe electronic configurations
- Knowledge of historical models and their evolution