The sketch graph shows the 13 successive ionization energies of aluminium. Define the term first ionization energy.

The first ionization energy is the energy required to remove the most loosely held electron from one mole of neutral gaseous atoms to produce 1 mole of gaseous ions each with a charge of 1+.

The sketch graph shows the 13 successive ionization energies of aluminium. Explain how the graph provides evidence for the existence of three electrons shells in an aluminium atom.

The Ionization energy increases with an increase in nuclear charge, and it also depends upon the electronic configuration of an atom, if the orbitals are fulfilled or half filled, then a high amount of energy is required to remove an electron from fulfilled or half filled orbitals. The electronic configuration of Al = 1 s 2 2 s 2 2 p 6 3 s 2 3 p 1 . Here in the graph, it is indicating that after the removal of three electrons from the shell ionization energy sharply increases.So the valency of the element is three.

The table shows the first ionization energies, IE 1 ,in KJmol - 1 , of the elements in the period 3 of the periodic table. Element Na Mg Al Si P S Cl Ar IE 1 494 736 577 786 1060 1000 1260 1520 Explain why there is a general increase in the value of IE 1 across the period.

The general increase in the value of IE 1 across the period is seen because the size of the atom decreases from left to right as the nuclear charge increases. With the increase in nuclear charge the force of attraction between the nuclease and the electrons increases, and thus the removal of electrons becomes difficult. So ionization enthalpy increases from left to right of the periodic table.

The table shows the first ionization energies, IE 1 ,in KJmol - 1 , of the elements in the period 3 of the periodic table. Element Na Mg Al Si P S Cl Ar IE 1 494 736 577 786 1060 1000 1260 1520 Write the electronic configuration for argon ( Z = 18 ) using 1 s 2 notation.

The electronic configuration of argon ( Z = 18 ) is as follows: Ar 18 = 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 It is in group 18 of the periodic table and is a noble gas. Argon is often used when an inert atmosphere is needed. It is used in this way for the production of titanium and other reactive elements. It is also used by welders to protect the weld area and in incandescent light bulbs to stop oxygen from corroding the filament.