Atomic Structure Cheat Sheet

Key Definitions

• Atom: Smallest unit of matter, retains properties of an element. ✅

• Element: Substance consisting of only one type of atom. ✅

• Molecule: Two or more atoms bonded together. ✅

• Isotope: Atoms of the same element with different numbers of neutrons. ✅

Important Concepts

Structure of an Atom

• Nucleus: Contains protons and neutrons. ✅

• Electrons: Negatively charged particles orbiting the nucleus. ✅

• Proton: Positive charge, determines atomic number. ✅

• Neutron: No charge, contributes to atomic mass. ✅

Atomic Number & Mass Number

• Atomic Number (Z): Number of protons in an atom. ✅

• Mass Number (A): Total number of protons and neutrons. ✅

• Relationship: A = Z + N (where N = number of neutrons) ✅

Key Formulas

• Number of Neutrons: N = A - Z ✅

• Electron Configuration: Shows distribution of electrons in atomic orbitals. ✅

Common Mistakes to Avoid

Common Mistake: Confusing atomic number with mass number. Remember, atomic number is the number of protons only.

Memory Tricks

Tip: "PEMDAS" — Parentheses, Exponents, Multiplication and Division, Addition and Subtraction (for order of operations in calculations).

Key Diagrams

     +-------+
     |       |
     | Nucleus|
     |       |
     +-------+
        | | 
  +-----+ +-----+
  | Electron   |
  |  Shells    |
  +-------------+