Chemical element and Metallic element

Chemical element noun - Any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter.

Metallic element and chemical element are semantically related. In some cases you can replace phrase "Metallic element" with "Chemical element", this phrases are similar.

Metallic element noun - Any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc..

Chemical element and metallic element are semantically related. You can use "Chemical element" instead a noun phrase "Metallic element".