Chemical element and Oxygen

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.

Oxygen and chemical element are semantically related. In some cases you can replace term "Oxygen" with "Chemical element", this terms are similar.

Oxygen noun - A nonmetallic bivalent element that is normally a colorless odorless tasteless nonflammable diatomic gas; constitutes 21 percent of the atmosphere by volume; the most abundant element in the earth's crust.

Chemical element and oxygen are semantically related. You can use "Chemical element" instead a noun "Oxygen".