[4][5] She previously held the Crum Brown chair in the School of Chemistry, University of Edinburgh from 2007 to 2019 and an Engineering and Physical Sciences Research Council (EPSRC) career fellowship.

[3] She studied chemistry at Brasenose College, Oxford (BA) and worked with Dermot O'Hare [Wikidata] and Matthew Rosseinsky.

[10][6] Arnold was a Fulbright Program postdoctoral fellow at Massachusetts Institute of Technology (MIT) where she worked with Christopher C. Cummins before returning to the UK to a lectureship in 1999.

[12] Her research is focused on the design and synthesis of highly reactive f-block complexes that can activate inert small molecules such as carbon oxides, dinitrogen, and hydrocarbons, and that can provide fundamental information on structure and bonding at the bottom of the periodic table.

[20] She was appointed Officer of the Order of the British Empire (OBE) in the 2017 Birthday Honours for services to chemistry and women in STEM.