# Element with No Proton?

On seeing this graph closely I noticed the there a element with no proton. But with no proton there will be no electron too and don't think that an lone neutron would form an element. So is that given a half-life on neutron OR there exist a element (isotope) with no electron?

• No, that is not a chemical element, it is an isolated neutron with a lifetime of few minutes. It undergoes beta decay into a proton, an electron and an antineutrino. – Wildcat May 31 '15 at 17:40
• It's but a matter of convention. You may consider there is an element with atomic number 0 (BTW, recently a tetraneutron has been supposedly discovered, which would be another isotope of it). Instability is not a big deal; a good many respectable elements are unstable. But it would be an element without chemistry. – Ivan Neretin Feb 6 '16 at 9:10

Free neutrons could be included on the graph as they are unstable and decay with a half life of around 10 minutes ($611.0\pm1.0~\mathrm{s}$) although most versions I have seen do not usually include them as they aren't really nuclei which is what the graph is about.