Electron configuration and Aufbau principle

Why is the second ionisation energy always higher than the first ionisation energy ?

• After the first electron is removed, the atom becomes a positively charged ion, making it more difficult to remove another electron due to stronger attraction to the nucleus.

Why do energy levels split into sub-levels (s, p, d, f) in many-electron atoms ?

Electron-electron repulsion causes the splitting of main energy levels into sub-levels

What is the wavelength of the convergence limit in the Lyman series for hydrogen, and how does it relate to ionisation energy ?

• The convergence limit is at a wavelength of 91.46 nm. This value helps calculate the ionisation energy of hydrogen when converted to energy using E=h×c/λ.

What is the significance of successive ionisation energies ?

Successive ionisation energies increase because removing an electron from a positive ion requires more energy due to stronger attraction to the nucleus.

What is the significance of large jumps in successive ionisation energies ?

• Large jumps indicate that an electron is being removed from an inner shell, which is closer to the nucleus and more strongly attracted.

What is the shielding effect, and how does it impact ionisation energy ?

Inner electrons shield outer electrons from the attractive force of the nucleus, making it easier to remove outer electrons.

What is the relationship between the energy of a photon and its frequency ?

E=h×f, where:

• E = energy of the photon

• h = Planck's constant (6.63 × 10⁻³⁴ Js)

• f = frequency (Hz)

What is the photoelectric effect, and how does it relate to ionisation energy ?

The photoelectric effect shows that light consists of photons, which can ionise atoms if they have enough energy, illustrating that light behaves as particles.

What is the Pauli exclusion principle ?

The Pauli exclusion principle states that a maximum of two electrons can occupy an orbital, and they must have opposite spins.

What is the formula for calculating the maximum number of electrons in each main energy level ?

The formula is 2n², where n is the principal energy level.

• Example:

  • n = 1: 2(1)² = 2 electrons

  • n = 2: 2(2)² = 8 electrons

What is the electron configuration, and how is it represented for elements with up to 36 electrons ?

• Electron configuration represents how electrons are arranged in energy levels or shells.

• Example for Sodium (Na): 2.8.1

What is the difference between the wave theory and particle theory of light in the context of ionisation energy ?

• Wave theory: Describes light as waves with wavelength and frequency.

• Particle theory: Describes light as photons (packets of energy), with each photon capable of ionising atoms if it has enough energy.

What is the definition of the first ionisation energy ?

The first ionisation energy is the energy required to remove the first electron from a neutral gaseous atom.

What is the Aufbau principle ?

• The Aufbau principle states that electrons fill sub-levels from the lowest energy upwards. (EXCEPT CHROMIUM AND COPPER)

• Electrons fill in the order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, etc.

What is meant by "degenerate" in the context of atomic orbitals ?

Degenerate orbitals are orbitals within the same sub-level that have the same energy (e.g., all three p orbitals in the 2p sub-level).