ion

/ion/

Cases

SingularPluralWhen to use it
nominativeionthe ionionlathe ionsthe plain dictionary form — the doer of the sentence
genitiveionnuthe ion'sionlanıthe ions'the owner — whose it is
accusativeionnuthe ion (as the object)ionlanıthe ions (as the object)a specific, known object — whom or what
dativeiongato the ionionlağato the ionsdirection or recipient — to where, to whom
locativeiondaat / in the ionionladaat / in the ionswhere it is; also having — mende bar, "I have it"
ablativeiondanfrom the ionionladanfrom the ionswhere it comes from; also "than" when comparing
When to use each case
nominative
the plain dictionary form — the doer of the sentence
genitive
the owner — whose it is
accusative
a specific, known object — whom or what
dative
direction or recipient — to where, to whom
locative
where it is; also having — mende bar, "I have it"
ablative
where it comes from; also "than" when comparing

The endings are the same ones the pronouns wear — that page explains when each case is used.

With an owner

One ownedSeveral owned
myionummy ionionlarımmy ions
yourionungyour ionionlarıngyour ions
his / herionuhis / her ionionlarıhis / her ions
ourionubuzour ionionlarıbızour ions
you all'sionuğuzyou all's ionionlarığızyou all's ions
theirionlarıtheir ionionlarıtheir ions

The overlap in the last rows is real, not a mistake: ionları can mean "his / her ions", "their ion", or "their ions" — context decides.