This is the 5485th most frequent Polish word.
tlenku
The Polish word "tlenku" means "oxide" in English.
Here, 'tlenków' is the plural genitive case of 'tlenek', referring to various types of oxides in chemistry.
W chemii uczymy się o różnych rodzajach tlenków.
In chemistry, we learn about different types of oxides.
In this sentence, 'tlenek' is in the nominative case singular form of 'tlenek', used to name the compound.
Tlenek azotu jest gazem bardzo reaktywnym.
Nitrogen oxide is a very reactive gas.
Here, 'tlenków' is in the genitive plural case of 'tlenek', modifying 'metali' to express the study subject.