Oganesson
Oganesson has the highest atomic number and highest atomic mass of all known elements. The radioactive oganesson atom is very unstable, and since 2005, only five (possibly six) atoms of the nuclide Og have been detected. Although this allowed very little experimental characterization of its properties and possible compounds, theoretical calculations have resulted in many predictions, including some surprising ones. For example, although oganesson is a member of group 18 – the first synthetic element to be so – it may be significantly reactive, unlike all the other elements of that group (the noble gases). It was formerly thought to be a gas under normal conditions but is now predicted to be a solid due to relativistic effects. On the periodic table of the elements it is a p-block element and the last one of the 7th period.
Frederick Woodward Branson
"Mr. Branson first showed that radium is an element having the highest atomic weight known, and has a characteristic spectrum, by which it can be easily identified, and that it falls into the group of metals: barium, calcium, and strontium. He then showed the difference between atmospheric (sound) waves and ether waves (heat, light, and electrical), and alluded to the emanations given off by radium as consisting of electrons negatively charged, and also much larger particles of matter termed ions positively charged. The former have very penetrative powers as regards metals and opaque bodies, and are identical with the kathode rays that are given off in an ordinary X-ray tube.