Periodicity

First ionisation energy

The energy required for the removal of 1 mole of electrons from 1 mole of gaseous atoms

What is first ionisation energy measured in

KJ/mol^-1

What is the abbreviation for first ionisation energy

Delta H subscript IE1

Factors affecting FIE

Electron shielding, atomic radius, nuclear charge

How does electron shielding affect FIE

As number of electron shells between nucleus and outer shells increases, FIE decreases as there’s less attraction

How does atomic radius affect first ionisation energy

As atomic radius decreases there is less distance between outer electrons and nucleus so attraction increases and FIE increases

How does nuclear charge affect FIE

As the number of protons in nucleus increase so does nuclear charge- there is a greater attraction between nucelus and outer electrons so FIE increases

How does FIE change across a period

There is a general increase- number of protons increases so more attraction, electrons are drawn in slightly due to increased attraction-atomic radius decreases further increasing attraction, electrons are added to the same shell so shielding is the same, atomic radius

What happens to FIE between periods

Sharp decrease- addition of new shell= more shielding + great distance to outer shell form nucelus therefore less attraction

What are the repeating patterns seen across the period table called

Periodicity

How does FIE change down a group

Decreases- number of shells increases- distance between outer shells+ nucleus increase, more inner shells= more shielding = less attractive force

How to write FIE of elements eg Na

Na(g0 → Na+(g) + e-

How to write 2nd IE of elements eg Na

Na+(g) → Na2+(g) + e-

What can successive ionisation energies (previous cards) be evidence for

Electron shells

Why do you see a drop in FIE between Mg and Al

Al has outer electrons in a 3p sub shell so has more energy than the outer electron of Mg which is in a 3s subshell so LESS energy is needed to remove it so FIE is lower

Why do we see a drop in FIE between P and S

We see repulsion in the 3p subshell that holds the 2 outer electrons of S so less energy is needed to remove one of them meaning the FIE of S is less than P

Atomic radius

Half the Inter nuclear distance in bonded atoms

How does atomic radius change across a period

Decreases as proton number increases o nuclear charge increase so the nucleus has a stronger attraction to electrons so they are pulled close to the nucleus

How does electronegativity change across a period

Increases as across a period the umber of protons in the nucleus increases and atomic radius decreases so there’s a stronger attraction between the nucleus and 2 electrons in a covalent bond

Why does BP and MP increase from Na→Mg→Al

All metallic elements- have strong attraction between metal ions and delocalised electrons, Al is highest as highest charge, more delocalised electrons, smaller ions ad higher charge density

Across period 3 why doe BP and MP spike at Si

Is a giant covalent molecule- has to break may strong covalent bonds, has a macro molecular structure similar to diamond, each Si atom is bonded to 4 carbon shy strong CB that need lots of energy to break

Why does BP and Mp drop off to P and then increase again to s before decreasing further to Cl

They are simple molecular with weal van der waals forces that require little energy to overcome, Cl is the lowest due to elemental forms P4 S8 Cl2- S8 has most electrons in so more forces that need to be broken

Why does Air have the lowest MP and BP of period 3

Is monatomic- has only LDF between atoms and no molecules are formed