Electronic Configurations and Ionisation Energy

• What is does n represents in energy level

  Principal Quantum Number
• What are shells made of?

  Subshells
• Please list down the number of electrons each subshell can hold in the sequence of; s, p, d, f

  2, 6, 10, 14
• Please describe the shape of s orbital

  Spherical
• Please describe the shape of d orbital

  Double dumbbell
• Please state the first 5 energy level in ascending manner

  1s 2s 2p 3s 3p
• What is the unique property possessed by an electron?

  Spin
• How spins help electrons to fit into an orbital?

  Counteract the natural repulsion between their negative charges
• Does electron have opposite or similar spins ?

  Opposite
• What are the three rules to determine the way in which electrons will fill the orbitals ?

  Aufbau principle, Hund's Rule and Pauli's exclusion principle
• Hund's rule: "Electrons ____ pair up in the ____ orbital until all ____ of the same are ____ occupied, and all ______ electrons have ____ spins 


  never, same, orbitals, singly, unpaired, parallel
• Pauli's Exclusion: Only ____ electrons may occupy the ____ orbital, and they must do so with ____ ____


  2, same, opposite, spin
• Aufbau Principle: "____ always fill the ____ energy levels ____


  Electrons, lowest, first
• What does isoelectronic means? Same number of ____ and same _____ ______

  electrons, electronic configurations
• What are the two exceptions in electronic configurations?

  Chromium and Copper
• What are the reason for Cr and Cu to be the exception? This is because, a completely ____ or ____ full ____ sub-level is more ____ than a ____ filled d sub-level, so an ____ from the ____ orbital is ____ and rises to a ___ orbital.

  filled, half, d, stable, partially, electron, 4s, excited, 3d
• Please write down the correct Cu electronic configuration

  4s1 3d10
• Please state the correct electronic configuration for Cr

  4s1 3d5
• how many electrons can d sub-shell hold?

  10
• How many electrons can f sub-shell hold?

  14
• Which subshell can hold 6 electrons?

  p sub-shell
• Which sub-shell can hold 2 electrons?

  s sub-shell
• What are the four subshell?

  s, p, d, f
• How many electrons can the 4th shell hold?

  32
• Which energy level can hold 8 electrons?

  n=2
• How many electrons n=3 can hold?

  18
• How many electrons can be hold by the 1st shell?

  2
• How many ionisations energies are there?

  Same as electrons
• Define the term ionisation energy

  The energy required to remove one electron from an atom in it's gaseous state
• What are the factors affection Ionisation energy?

  The charge on the nucleus, distance of electron from nucleus, number of electron between valence electrons and nucleus
• How the charges on the nucleus affect IE?

  The more protons there are in the nucleus, the more positively charged the nucleus is, and the more strongly electrons are attached to it. Thus, the ionisation energy increases as the energy required to remove an electron increases
• How does the distance of electron from nucleus affect IE?

  The closer the electron is to nucleus, the more attracted the electron is, causing it harder to remove an electron. Thus, thus ionisation energy increases
• How does the number of electrons between valence electrons and nucleus affect the ionisation energy?

  The more number of electrons in the inner shell orbit, the more shielding it is, valence electrons feeling less pull from the positive charges of the nucleus. Thus, ionisation energy decreases
• What are the ionisation energy trend in the periodic table?

  Across the period: Ionisation energy increases

  Down the group: Ionisation energy decreases
• Ionisation energy decreases down the group

  Increase in nuclear charge

  Increase in shell number

  Atomic radius increase

  Electron shielding effect increases (valence electrons are held loosely; easier to remove)
• Ionisation trend increases across the period

  Increase in nuclear charge

  Same shell number

  Atomic radius decreases

  Constant shielding

  Electrostatic attraction for electrons increases (valence electrons are tightly held; harder to remove)
• Which four element causes dips in the ionisation energy ?

  Beryllium and boron

  Nitrogen and oxygen
• Why is there a dip between beryllium and boron?

  Be (4) : 1s2 2s2

  B (5): 1s2 2s2 2p1

  Boron has a lower ionisation energy than beryllium although boron has an extra proton than beryllium. Boron has an extra electron in the 2p shell which is further away from nucleus that has more shielding. Thus, the ionisation energy of beryllium is higher than boron that has an extra electron that can be removed easily.
• Why is there a dip in trend between nitrogen and oxygen?

  Oxygen: 1s2 2s2 2p4

  Nitrogen: 1s1 2s2 2p3

  Oxygen has slightly lower ionisation energy because of there are 2 more electron present in the 2p shell in oxygen. The spin-pair repulsion allow those electrons to be removed easily.