yuánzì Chinese characters of the chemical elements

tóng

“same, similar; together with”

On its own, an ordinary character; Cantonese tung4. Readings and gloss from the Unicode Unihan database.

Carries Copper

metal → solid metal
+
tóng
=
tóng · Cu 29

Not a plain transliteration: the component was chosen for its meaning, or the name is older than the system.

The element keeps the component’s reading exactly.