This is the 4585th most frequent Polish word.
magnezu
"Magnesium" (chemical element).
Here, 'magnezu' is used as the genitive case of 'magnez' to indicate the necessity for magnesium.
Potrzebuję więcej magnezu w mojej diecie.
I need more magnesium in my diet.
In this sentence, 'magnezu' is again in the genitive case, referring to the properties of magnesium.
Na lekcji chemii uczymy się o właściwościach magnezu.
In the chemistry class, we learn about the properties of magnesium.
Here, 'magnezu' reflects the direct action of adding magnesium to a solution, conveying the material's involvement in the process.