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An ATOMIC ORBITAL refers to a region in space where there is a high probability of finding an electron.

 

ALL orbitals can contain a maximum value of two electrons. There are many different variations of atomic orbitals;

s

p

d

f and more

 

Each kind of orbital has its own characteristic shape and its own associated energy

The Quantum mechanical model of the atom 

Figure 1: atom orbital structure

An S atomic orbital is spherically symmetrical. The sphere represents a boundary surface. This means that within the sphere, there is a 99% chance or probability of finding an electron. (fig 2)

The S atomic orbital

Figure 2 The S atomic orbital

 

 

The P atomic orbital 

A p orbital is dumbshell shaped. There are three p atomic orbitals, Px' Py' Pz'.

 

All of the orbitals have boundary surfaces which express probable electron density. They point in varying directions along the Cartesisian axes x, y and z, this is also known as a 3D axis. (figure 3)

Figure 3 - The P atomic orbital

The Bohr model introduced the concept of a main energy level. This was represented by n and was also known as the principal quantum number.

 

Throughout the quantum mechanical model, there is a positive correlation between the energies of the orbitals, and n.

 

As n increases, the energies of the orbitals also increase. The mean position of the electron is also further away from the nucleus.

 

The principal quantum number can have positive integer values.

 

A maximum of 2nr electrons can be held inside each main energy level OR shell. SO, the electron capacity for n=1 is 2, for n=2 is 8, for n= 3 is 18.

 

The energy levels are split up into sublevels; there are four different common types; s, p , d and f.

 

For every sublevel ,there are a set quantity of orbitals. (TABLE A)

Energy levels, sublevels, orbitals and electron spin

Sublevels of the main energy levels in the quantum mechanical model

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