A question of more efficient coding.

[si_the_geek]

If you are going use If statements to compare a variable/control value against multiple values, it is simpler to use a Select Case. One way would be like this:

Select Case MaskedTextBox1.Text
Case "H"
   MsgBox "MaskedTextBox1.Text equals 'H'"
Case "Li"
   MsgBox "MaskedTextBox1.Text equals 'Li'"
...
End Select

However, as it is this wont save much typing... thankfully you can use more than one value per case (simply separate them using commas), so you can do this:

Select Case MaskedTextBox1.Text
Case "H", "Li", "Na", "K", "Rb", "Cs", ...
   TextBox1.Text = print(0)
End Select

It would also be possible to loop the elements arrays, but as your data doesn't contain the letters on their own it would be fairly "messy" code, and so it may be better to avoid that.