Overview
This lecture covers the fundamentals of matter, atomic structure, isotopic notation, and how to determine protons, neutrons, and electrons for various atomic species using isotopic symbols.
Definitions of Matter and Atoms
- Matter is anything that occupies space and has mass.
- An atom is the basic unit of matter, consisting of a central nucleus and surrounding electrons.
Subatomic Particles
- Atoms contain three key subatomic particles: protons (positive), neutrons (neutral), and electrons (negative).
- Protons and neutrons are located in the nucleus, while electrons orbit around the nucleus.
Atomic Mass and Isotopic Notation
- The mass number (A) equals the sum of protons and neutrons in the nucleus (A = protons + neutrons).
- The atomic (proton) number (Z) is the number of protons in the nucleus.
- Isotopic notation:
- Written as:
A
Z X
where X is the element symbol, A is mass number, and Z is atomic number.
Isotopes
- Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
- Example: Hydrogen has three isotopes—protium (no neutron), deuterium (one neutron), and tritium (two neutrons).
Calculating Subatomic Particles and Charge
- Neutrons = mass number (A) – proton number (Z).
- For neutral atoms, protons = electrons.
- For charged species (ions):
- Negative charge = extra electrons added.
- Positive charge = electrons removed.
- Example: O²⁻ (oxide ion) has 8 protons and 10 electrons (8 + 2 extra).
Key Terms & Definitions
- Matter — Anything that occupies space and has mass.
- Atom — The basic unit of matter with a nucleus and electron cloud.
- Proton — Positively charged particle in the nucleus.
- Neutron — Neutral particle in the nucleus.
- Electron — Negatively charged particle orbiting the nucleus.
- Mass number (A) — Total number of protons and neutrons.
- Atomic number (Z) — Number of protons in the nucleus.
- Isotope — Atoms of the same element with different numbers of neutrons.
- Species — Different forms of atoms or ions (e.g., isotopes, ions).
Action Items / Next Steps
- Practice writing isotopic notation for various elements and ions.
- Calculate the number of protons, neutrons, and electrons for given isotopic symbols.
- Review definitions and examples of isotopes.