User talk:50.245.33.5

An Element is a Set
The first sentence of the article could read: "In Chemistry, an Element is the set of all and only those atoms, each of which contains the same number of protons in its atomic nucleus as the others in the set." For example, 5 molecules of Oxygen is still as oxygen as 1 molecule of oxygen. All molecules of oxygen in the universe constitute the Element Oxygen. This is more concise than calling it a "pure substance", whatever that means.