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1

You are correct in noting that there are a number of Au (II) small molecule species synthesized prior to the report of Professor Katja Heinze in 2017. The heart of the Au (II) claim by Professor Katja Heinze and team as stated in the article you referenced, see reference 1 given below, has to do with the a) relative stability of the mono-nuclear gold-...


1

In $\ce{H2O}$, the proportion of $\ce{H}$ counted by atoms is $\ce{2/3 = 66.7}$ %. In the same $\ce{H2O}$, the mass of $\ce{2 H}$ is $2$ u. As the mass of $\ce{1 O}$ is $16$ u, the proportion of H by mass in $\ce{H2O}$ is $2/18 = 11.1$%. This percentage $11.1$% is rather different from $66.7$%


2

Unknown elements were discussed according to Mendeleiev's nomenclature. The prefix eka- was used for the element just under a known element, and it was dvi- for the following one, two lines under. For example, the element 31 under aluminum was celled eka-aluminum, just before it was discovered as gallium. With this same technique, the element 43 was named ...


7

The mole was promoted to the status of "unit" in 1971 The 14th Conférence Générale des Poids et Mesures (CGPM), considering the advice of the International Union of Pure and Applied Physics, of the International Union of Pure and Applied Chemistry, and of the International Organization for Standardization, concerning the need to define a unit of ...


18

The symbol mol is due to Ostwald who was a very influential and respected physical chemist more than a century ago. In German, "mole" is "Mol". It is a shortform of Molekül. I believe the Internet Archive has an English translation of his historically famous book of 19th century. This is where I recall reading this. The original reference ...


0

In the beginning of the $20$th century, the periodic table had $8$ columns, and not $18$ as today. Electrons and of course $spdf$ electrons were unknown. The numerous transition elements were included in this table by doubling the line between Argon and Krypton, then between Krypton and Xenon. It was going this way. The $4$th period was made of two lines. So ...


3

George B. Kauffman has edited an excellent book, "Coordination chemistry: A century of progress." It was published as an ACS Symposium Series. In the chapter, he writes, "If history teaches us anything, it teaches us that the latest view is not always the best and that change is not always progress." I may add that there is no authority ...


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