Where does “щёлочка” come from?

щёлочка (Russian) comes from Russian щёлка, from Russian -ка, from Proto-Slavic -ьka, from Proto-Balto-Slavic -ikaʔ, from Proto-Indo-European -ikeh₂.

Ancestry of “щёлочка”, step by step

StepLanguageWordMeaning
1Russianщёлка(small) slit, crack
2Russian-каnow, just
3Proto-Slavic-ьka—
4Proto-Balto-Slavic-ikaʔ—
5Proto-Indo-European-ikeh₂—
Every word from Proto-Indo-European -ikeh₂ →Every word from Russian -ка →Every word from Proto-Slavic -ьka →