Ionisation energy and atomic radius - atomic theory 7 - LC chem

Atomic radius def

Half the distance between the nuclei of two singly bonded atoms of the same element

Atomic radius going across a period..

Decreases

Why is there a decrease in atomic radius going across a period

• increase in nuclear charge

• No change in energy levels so screening effect of completed energy levels remains the same

• therefore outer electrons held closer to nucleus as positive nucleus pulls negative electrons towards itself

Atomic radius going down a group

increases

Why does atomic radius increase going down a group

• increase in number of energy levels

• screening effect of electrons in inner energy levels block some of the pull the nucleus has on outer electrons

• outer electrons further away, therefore less closely held, leading to larger atomic radius

first ionization energy

minimum amount of energy required to remove first most loosely bound electron from a mole of isolated atoms of an element in its neutral gaseous ground state

trends for ionisation energy

increase going across a period

decrease going down a group

explain why there is an increase in ionisation energy across a period

because the atomic radius gets smaller due to an increase in the effective nuclear charge and no change in nuclear charge

Why is there a decrease in ionisation energy going down a group

• Increase in atomic radius due to extra shells being added, inner completed shells screen out some of the nuclear attraction

metals + oxygen

form metal oxide

flourine and chlorine are

yellow green gasses

account for difference in ionisation energy between . and .

• radius size

• stability of energy shell

• stability of sublevel

• second / subccessive ionisation energies

How does distance from the nucleus effect ionisation energy

• smaller atomic radius, more energy required to remove the electron as positive nucleus will have a greater hold on electron

How does stability of energy level impact

full sublevel is most stable, next most stable is half full

checklist for questions w ionisation energy

• distance of electron from nucleus

• stability of sublevel

• stability of shell from which electron is being removed

• removing electron from ion or atom