An isotope of an element has a slightly different number of particles to other isotopes of the element. So, the most common isotope of oxygen is oxygen-16, and it has 16 nucleons (both protons and neutrons) in its nucleus. Oxygen-18 has 18 nucleons.
Fact of the Day
Pounds, shillings and pence were rooted in Roman librae, solidi and denarii. This is where the abbreviation LSD comes from.
Quote of the Day
"The Englishman can tolerate a significantly greater dose of anarchy [than the Prussian]. "
~ Highly-decorated WWI and WWII veteran Ernst Jünger
On This Day
43 BCE The assassination of Cicero, requested by Marc Antony. When his head was delivered to Anthony, his wife, Fulvia, spat on it and jabbed hairpins into his tongue.
1732 The Theatre Royal, now known as the Covent Garden Opera House, opened with a performance of the Beggar's Opera.
1787 Delaware became the first state of the modern United States.
1817 Rear-Admiral William Bligh died. He had been captain of HMS Bounty during the mutiny.
1941 The Japanese launched a surprise attack on the American naval base a Pearl Harbour, Hawaii, killing 2,403.
1982 Charles Brooks Jr became the first person to be executed by lethal injection, with a huge dose of 'truth serum'