Electrons in Atoms

Principal Quantum shell

Electrons are arranged outside the nucleus i energy levels or principle quantum shells, n. They are numbered according to how far they are from the nucleus (n=1<n=2, ...)

Ionization energy

It is the minimum amount of energy required to remove the most loosely bound electron of an isolated neutral gaseous atom or molecule

The first ionization energy is the energy required to remove one mole of the most loosely held electrons from one mole of gaseous atoms to produce 1 mole of gaseous ions each with a charge of 1+. This is more easily seen in symbol terms.

Factors that influence ionization energy

Size of the nuclear charge

Ionization energy generally increases as proton number increase

Distance of outer electrons from the nucleus

The further the outer electron shell is from he nucleus, the lower the ionization energy.

Shielding effect of inner electrons

The ionization is lower as the number of full electron shells between the outer electrons and the nucleus increase

Sub-shells and Atomic Orbital

S orbital

All the S orbital are spherical and have only 1 orbital. The size of the S orbital increase in the order 1s<2s<3s<4s

P orbital

All the P orbital are dumb-bell shaped and have 3 orbitals (Px, Py, Pz). P orbitals are only available from the second principal quantum shell and onwards.

D orbital

The D orbital has a clover shape and have 5 orbitals (Dxy, Dyz, Dxz,, Dx2y2, Dz2).

Energy levels

Electric Configuration and important points

watch this video to grasp a better understanding

Patterns of Ionization energy

Across a period

Ionization energy generally increases moving from left to right across an element period (row). This is because the atomic radius generally decreases moving across a period, so there is a greater effective attraction between the negatively charged electrons and positively-charged nucleus. Ionization is at its minimum value for the alkali metal on the left side of the table and a maximum for the noble gas on the far right side of a period. The noble gas has a filled valence shell, so it resists electron removal.
There is a rapid decrease between the last element in one period and the last element in the next period. Helium has 2 electrons that are in the first S subshell but lithium have 3 electrons, the third electron is in the second S subshell, thus the force of attraction between the nucleus and the valence electron decreases because the distance and shielding effect increases.
There is a slight decrease between Beryllium and Boron because the valence electron of Beryllium is at 2S2 while the valence electron of Boron is at 2P1. Therefore, there is less attraction between the fifth electron in Boron and the nucleus because the distance between the nucleus and valence electron increases as well as the shielding effect.
There is a slight decrease between Oxygen and Nitrogen. Oxygen has one more proton than Nitrogen and the electron removed is in the same 2P subshell. How you ask? This is caused by the spin pair repulsion in the orbital , the P orbital has 3 orbital that can hold 2 electrons each and they follow a pattern where they fill it each orbital with one electron and then continue filling it after 3 electrons are filled.

Down a group

Ionization decreases moving top to bottom down an element group (column). This is because the principal quantum number of the outermost electron increases moving down a group. There are more protons in atoms moving down a group (greater positive charge), yet the effect is to pull in the electron shells, making them smaller and screening outer electrons from the attractive force of the nucleus. More electron shells are added moving down a group, so the outermost electron becomes increasingly distance from the nucleus.

Hybridization

Hybridization is the idea that atomic orbitals fuse to form newly hybridized orbitals, which in turn, influences molecular geometry and bonding properties. Hybridization is also an expansion of the valence bond theory. Initially, they are at a grounded state where no electrons are shared, however when they enter the excited state, one electron from the s orbital moves to the p orbital allowing electrons to enter the orbital as shown in the picture =>

SP hybridization

In sp hybridization, one s orbital and one p orbital hybridize to form two sp orbitals, each consisting of 50% s character and 50% p character. This type of hybridization is required whenever an atom is surrounded by two groups of electrons.

SP2 hybridization

The sp² hybridization is the mixing of one s and two p atomic orbitals, which involves the promotion of one electron in the s orbital to one of the 2p atomic orbitals. The combination of these atomic orbitals creates three new hybrid orbitals equal in energy-level.

SP3 hybridization

The term “sp³ hybridization” refers to the mixing character of one 2s-orbital and three 2p-orbitals to create four hybrid orbitals with similar characteristics. In order for an atom to be sp³ hybridized, it must have an s orbital and three p orbitals.

These are videos that I recommend to watch

Just by watching these videos, I understand the process of hybridization from its ground state to its excited state. The topic of cis and trans isotopes never had crossed my mind because I didn't know the Pie bond to be able to rotate and the drawings that Mr Gopi, the man himself made is abnormally specific that its so easy to understand just by looking at it.

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