iHub Chem Assessment Unit 1

​Back in 1920, one of the most sought after jobs on the East Coast was a dial painter at a watch factory. These workers were all female, and they absolutely loved their jobs. These girls were instructed to paint the number on a watch with paint laced with an element called radium. 

Years later, many of these workers developed many medical problems with their bones. Some girls lost their jaw bones, and others’ bones broke when they walked across a room. Several doctors thought that phosphorus poisoned the girls’ bones. Their companies insisted that radium was not damaging their bones in order to avoid a lawsuit.  

• Was it the radium or the phosphorus that poisoned the girls’ bones? 

• Were the factories responsible for the girls’ sicknesses?

​Calcium from milk and dairy in the diet is stored in bone tissue until humans are in their mid-20s. Calcium moves around the body as an ion. Doctors suspected that another ion - either phosphorus or radium - was deposited instead of calcium in the workers’ bones.

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How could you figure this out?

​In 1920, no one knew about ions. Which substance is more likely to be acting as calcium ions in bones of young shopworkers? You identify important patterns in calcium ions compared to radium and phosphorus and determine which element- phosphorus or radium- is more likely to have replaced the calcium ions in the workers’ bodies and caused their ailments.