⚛️ Core Concepts covered

• Matter: Anything composed of atoms and molecules. That’s EVERYTHING!

• Atoms: The fundamental building blocks of matter. They consist of:

  • Protons (p+): Located in the nucleus; positive charge.

  • Neutrons (n0): Located in the nucleus; neutral charge.

  • Electrons (e-): Orbiting the nucleus in the electron cloud; negative charge.

• Atomic Number (Z):

  • The number of protons in an atom’s nucleus.

  • Key: The atomic number defines the element!

• Mass Number (A):

  • The total number of protons and neutrons in an atom’s nucleus.

  • Formula: A = Z + N (where N is the number of neutrons)

• Avogadro’s Number (Nᴀ):

  • 6.022×10(23)

  • Represents the number of particles (atoms, molecules, ions, etc.) in one mole of a substance.

🧮 Essential Formulas: Your Toolkit!

Make sure you understand and can use these formulas:

• Number of Moles (n):

  • n = (mass (g) / molar mass (g/mol))

  • n = (number of particles / Avogadro’s number)

• Density (ρ):

  • ρ=(mass / volume)

• Concentration (C):

  • C=nVC=Vn (number of moles / volume)

⚠️ Key Distinction: Don’t Get These Confused!

• Atomic Mass vs. Mass Number:

  • Mass Number (A): A whole number representing the total count of protons and neutrons.

  • Atomic Mass: The weighted average mass of all isotopes of an element, measured in atomic mass units (amu). It is NOT the same as the mass number!