Question

what will be the order of Na,Mg,Al and Si in the terms of first ionization enthalpy​

Answer 1

As we can see, all the elements are given from period 3 of the periodic table.

And,

From the properties of periodic table, we know that the ionisation enthalpy ( or ionisation potential ) increases on moving from left to right in a period. And, increases on moving bottom to top in a group.

Here, all the elements are belonging from the same period.

Therefore,

The order of the elements in terms of ionisation enthalpy will be arranged on the increasing order of valence electrons.

As Na has the least numbers of valence electrons in group 3, it will be arranged at 1st place, if order is being arranged in increasing order.

Similarly, all the elements will be arranged on the same basis.

Hence,

The order should be ( in increasing order ) : Na , Mg, Al , Si

Or, ( in decreasing order ) : Si, Al , Mg , Na .

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But there's an exception with Mg.

Correct order is Na, Al, Mg,Si.

Answer 2

Answer:

Na > Al > Mg > Si.

Explanation:

Ionization enthalpy

The ionization enthalpy of an element can be defined as the amount of energy required to remove an electron from an isolated gaseous atom in its gaseous state.

Factors on which Ionization enthalphy depends upon-

Ionization enthalphy depends upon the following factors-

1. Penetration effect
2. Shielding effect
3. Electronic configuration

1. Penetration Effect

Penetration means the proximity of an electron in an orbital to the nucleus. For each shell and subshell, it can be observed as the relative density of electrons near the nucleus of an atom.

The order of penetration power will be 2s > 2p > 3s > 3p > 4s > 3d

2. Shielding Effect

The shielding effect can be defined as the effect in which the inner electrons develop a shield for the electrons in outer shells which does not let the appropriate nuclear charge towards the outermost electrons. Due to this, the outermost electrons experience a low effective nuclear charge and not the actual nuclear charge

The effective nuclear charge can be given as:

Z effective = Z–S

Z effective -> effective nuclear charge

Z-> actual nuclear charge

S -> screening constant

3. Electronic configuration

Elements having half-filled and fully filled orbitals are stable. So if we will try to remove an electron from these orbitals, then it will make them less stable. Hence, more amount of energy is required to remove an electron from these orbitals.

Thus, the elements having either half-filled or full-filled electronic configuration will have higher ionization energy.