Atomic Structure Formulas:

1. Bohr's Model:
- According to Bohr's model, electrons revolve around the nucleus in fixed orbits.
- The formula to calculate the radius of the nth orbit is:
r = n^2h^2 / 4π^2mkZe^2
where r is the radius, n is the orbit number, h is the Planck's constant, m is the mass of the electron, k is the Coulomb constant, Z is the atomic number, and e is the charge of an electron.

2. Energy Levels:
- The formula to calculate the energy of an electron in the nth orbit is given by:
E = -13.6 Z^2 / n^2
where E is the energy, Z is the atomic number, and n is the orbit number.

3. Quantum Numbers:
- The quantum numbers describe the properties of electrons in an atom.
- The principal quantum number (n) determines the energy level of an electron.
- The azimuthal quantum number (l) determines the shape of the orbital.
- The magnetic quantum number (m) determines the orientation of the orbital.
- The spin quantum number (s) describes the spin of the electron.

4. Aufbau Principle:
- The Aufbau principle states that electrons fill orbitals starting with the lowest energy level.
- The formula to determine the maximum number of electrons in a shell is given by:
2n^2
where n is the principal quantum number.

5. Pauli Exclusion Principle:
- The Pauli exclusion principle states that no two electrons in an atom can have the same set of quantum numbers.
- This helps in determining the electron configuration of an atom.
Understanding these formulas and principles is crucial in explaining the structure of an atom and the behavior of electrons within it.