Overview
This lecture introduces ions, explaining how atoms become charged by gaining or losing electrons, and distinguishes between cations and anions using sodium and nitrogen examples.
Atoms and Ions
- Atoms have equal numbers of protons and electrons, resulting in no net charge.
- An ion is an atom with unequal numbers of protons and electrons, causing a net electrical charge.
Types of Ions
- Cations are positively charged ions with more protons than electrons.
- Anions are negatively charged ions with more electrons than protons.
Examples of Ions
- Sodium atom (Na-23) has 11 protons, 12 neutrons, and 11 electrons (neutral).
- Sodium ion (Na⁺) still has 11 protons and 12 neutrons, but only 10 electrons, making it a cation.
- Nitrogen atom (N-15) has 7 protons, 8 neutrons, and 7 electrons (neutral).
- Nitrogen ion (N³⁻) keeps 7 protons and 8 neutrons but has 10 electrons, making it an anion.
Communication and Notation
- The charge of an ion is indicated by a superscript (e.g., +1, 3⁻) next to the element symbol.
- Understanding ion charges and proper notation is important for communicating in chemistry.
Key Terms & Definitions
- Ion — an atom with unequal numbers of protons and electrons, resulting in a net charge.
- Cation — a positively charged ion (more protons than electrons).
- Anion — a negatively charged ion (more electrons than protons).
Action Items / Next Steps
- Prepare to learn about isotopes, which involve variations in the number of neutrons, in the next lesson.