Ch 2: Atom: General Chemistry Lesson Plans

1. Atomic Number and Mass Number

An atom is defined as the smallest particle of an element that displays the same properties of that element. Learn about the main components of an atom (protons, neutrons, & electrons), the characteristics of each component, and how to determine the atomic number and the mass number of an atom.

2. Early Atomic Theory: Dalton, Thomson, Rutherford and Millikan

The current knowledge of atoms and atomic theory has been informed by many scientists going back to Aristotle and Democritus. Learn about the contributions made to early atomic theory by scientists working in more recent times, such as Dalton, Thomson, Rutherford, and Millikan.

3. Isotopes and Average Atomic Mass

Isotopes are variations of the same element with differing numbers of neutrons and, subsequently, different atomic masses. Learn how scientists consider isotopes when they calculate average atomic mass.

4. Avogadro's Number: Using the Mole to Count Atoms

Atoms are microscopic and challenging to count as a result. Learn about the importance of understanding the mole, which is simply a large number or quantity of something, also known as Avogadro's number, and how it helps scientists count large numbers of atoms.

5. Electron Configurations in Atomic Energy Levels

Electron configuration is the representation of how the electrons in an atom are arranged, which can be used to predict the properties of an element. Learn about patterns of energy levels in elements on the periodic table, how to identify the number of electrons in a neutral atom, and how to write an electron configuration for neutral atoms.

6. Four Quantum Numbers: Principal, Angular Momentum, Magnetic & Spin

Quantum numbers describe specific properties of an electron. Learn about atomic orbital, the four quantum numbers (principal, angular momentum, magnetic, and spin), and how to write quantum numbers based on electron configuration.

7. The Bohr Model and Atomic Spectra

The Bohr model of the atom established the existence of a positive nucleus surrounded by electrons in specific energy levels. As electrons move from higher-energy to lower-energy levels, energy in the atom is released in the form of photons. Learn about the Bohr Model, atomic spectra, and how electrons emit different colors of light.