Question

Why is the first ionization energy of a nonmetal much higher than that of an alkali metal in its same period? Provide an answer using 3 – 4 sentences in your own words.

Answer 1

Factors Affecting Ionisation Enthalpy=>

1) Size of the atom
I.E is inversely proportional to atomic size

2)Screening Effect
I.E is inversely proportional to Screening effect.

3)Nuclear Charge

I.E is proportional to Nuclear charge

4) Half filled and fully filled orbitals

The atoms which are half filled/full filled are more stable so more energy is required to remove the electrons from such atoms.

5) Shape of Orbital

s>p>d>f

------------------------

Answer 2

In a period(left=metals, right=non metals),the value of ionisation enthalpy increases from left to right with breaks where the atoms have somewhat stable configuration. The observed trends can easily be explained on the basis of increased nuclear charge and decrease in atomic radii.

Both the factors increase the force of attraction towards nucleus and consequently more and more energy is required to remove the electrons and hence I.E increase.

Answer 3

@arindameducationusc pointed out some valid points, but let's think of this in another way: ionization energy = amount of energy it takes to remove an electron from the farthest shell in a neutral atom.

Non metal = something that wants to gain an electron.
Metal = something that wants to lose an electron.

Answer 4

if something wants to naturally lose an electron say a metal, it's going to be easier to remove an electron from it.

conversely if you have a non metal it would be harder to remove an electron because non metals want to gain electrons not lose them, this especially the case if say the elements are in group 7.

Answer 5

That was nice @Photon336 ....

Answer 6

like when I first learned this they said oh Zeffective nuclear charge can basically explain all the trends in the periodic table

Answer 7

and it's funny because it actually does anyway cheers guys

Answer 8

The first ionization energy of an element is the energy needed to remove the outermost, or highest energy, electron from a neutral atom in the gas phase.
When we move from alkali metals to non metals ( left to right across a period)
The atomic radii of metals decreases .
Thus the attraction between outermost electron and the the nucleus increases making it hard to remove the outermost electron.