Seems like you have 3 possible approaches here:
1) Keep things like you have set them up. That really complicates your life as you have 10 different tables to maintain with lots of complications in your layout and table design that you don't really have to deal with if you use one of the other approaches.
2) Merge all 10 tables into a single table with all the property fields included in the same table. 200 fields is a lot of fields for a single table, but not unmanageably so. This is probably your simplest structure but it may not be as flexible as option 3.
3) Make each record a single property for a single element.
Thus for Hydrogen, you might have one record that reads: H | Atomic Number | 1 , another record that reads H | Boiling Point | Whatever the BP of Hydrogen is and so forth. For 200 properties for hydrogen, you'd use 200 records, one for each property. This is what has been suggested to you elsewhere. This can be especially useful if you only need to display the properties for a single element at any one time as you can present your properties for that one element in a vertical list where each row is a different property.
You'd use another table for the elment name and any other data on the element that isn't part of the list of 200 properties:
I don't see a join table here myself, just a one to many relationship between Element and Properties. Any links to your experiment table, would I think, be linked to the Element table--either directly if there is only one element specified for each experiment or via a different join table if multiple elements are to be linked to the same experiment (which would be typical of any chem labs I've ever worked with.)
ok thank you ....i think im just gonna keep it how it is, lol. because im not gonna be changing the values form these tables, just viewing it for comparisons. so once it's up and running i won't need to manipulate it.
You won't need to change the values, but separate tables like this will complicate how you display the data from them or use these values in any calculations you might choose to use. (Perhaps to generate an answer key for each lab?)