[portiagriffey]

Very simple question - I need to sit an equivalency exam and have never studies chemistry !!  First lesson my books, and asking the internet all puts the atomic number on top and the mass number underneath the symbol. But BBC bitesize chemistry and Oak National online year 9 lessons does it the other way around - what is the UK standard form? Thank you.

[Borek]

As far as I am aware there is no such thing as a "standard UK form", there is a standard notation defined by IUPAC in the Green Book (https://iupac.org/what-we-do/books/greenbook/), and it calls for the atomic number at the bottom.

[jeffmoonchop]

Its the smaller number