Overview
This lecture introduces isotopic notation, reviews key atomic structure concepts, and explains how to calculate protons, neutrons, and electrons in various isotopes and ions.
Definitions and Atomic Structure
- Matter is anything that occupies space and has mass.
- An atom is the basic unit of matter, consisting of a nucleus (protons and neutrons) surrounded by electrons.
- Subatomic particles for this level: protons (positive), neutrons (neutral), electrons (negative).
- Electrons orbit the nucleus while protons and neutrons reside inside the nucleus.
- The atom's mass number (A) is the sum of protons and neutrons.
Isotopic Notation
- Isotopic notation format: element symbol (X), mass number (A, top left), and atomic number (Z, bottom left).
- Mass number (A, nucleon number) = total protons + neutrons.
- Atomic number (Z) = number of protons.
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 (A=1, 0 neutrons), deuterium (A=2, 1 neutron), tritium (A=3, 2 neutrons).
- For a neutral atom, the number of protons equals the number of electrons.
Calculating Subatomic Particles in Species
- For a neutral atom: electrons = protons.
- For ions: add electrons for negative charge, subtract for positive charge.
- Example: Mercury (Hg) with A=200, Z=80 has 80 protons, 120 neutrons, 80 electrons (neutral).
- Copper (Cu) with A=63, Z=29 has 29 protons, 34 neutrons, 29 electrons (neutral).
- Oxygen (O^2-) with Z=8, A=17 has 8 protons, 9 neutrons, 10 electrons (extra 2 due to charge).
- Cobalt (Co^3+) with Z=27, A=59 has 27 protons, 32 neutrons, 24 electrons (lost 3 due to charge).
Key Terms & Definitions
- Atom — the smallest unit of matter with a nucleus and electrons.
- Proton — positively charged subatomic particle in the nucleus.
- Neutron — neutral subatomic particle in the nucleus.
- Electron — negatively charged subatomic particle orbiting the nucleus.
- Mass number (A) — total number of protons and neutrons in the nucleus.
- Atomic number (Z) — number of protons in the nucleus.
- Isotope — atoms of the same element with different numbers of neutrons.
- Isotopic notation — symbolic way to represent an atom's element, mass number, and atomic number.
Action Items / Next Steps
- Practice writing isotopic notation for given elements.
- Calculate protons, neutrons, and electrons for various neutral and charged species.
- Review definitions of key atomic terms.