Text reads: "On this Day: Februay 18th 1913. Introduction of the term 'isotope'. Frederick Soddy used the word, from the Greek meaning 'same place', to describe variants of elements which share chemical properties but have different atomic masses. In 1921 he won the Nobel Prize in Chemistry, in part for his 'investigation into the origin and nature of isotopes.'"

Chemistry Calendar: on this day in 1913, Frederick Soddy coined the term 'isotope'. You can explore more events in chemistry history - one for every day of the year, in fact - on the @rsc.org's Education website: edu.rsc.org/resources/co... #ChemistryCalendar #OnThisDay #Chemsky #ChemAtCam

Graphic celebrating Soren Sorenson, with images of Sorenson and the pJ scale. Text reads: "On this Day: January 9th 1868, birth of Danish Chemist Soren Sorensen. Sorensen developed the pH scale at the Carlsberg Laboratory in Denmark. This was the first time that the negative logarithm of proton (H+) concentration was used as a measure of acidity.

Chemistry Calendar: on this day in 1868, Danish chemist Søren Sørensen was born. Sørensen headed the prestigious Carlsberg Laboratory for over 30 years, where he developed the pH scale for measuring acidity. #chemistrycalendar #chemsky #chematcam