Before revision: Examples of free elements include the nitrogen molecule (N) and the hydrogen molecule (H) .Chemistry of the Elements (Second Edition) A. Earnshaw and Norman Greenwood ISBN: 978-0-7506-3365-9 Mentions "free element" 30 times, for example "Carbon occurs both as a free element and in combined form."
After revision: Examples of free elements include the oxygen molecule (O) and carbonnaturally occurring .Chemistry of the Elements (Second Edition) A. Earnshaw and Norman Greenwood ISBN: 978-0-7506-3365-9 Mentions "free element" 30 times, for example "Carbon occurs both as a free element and in combined form."