This was added because it may be more convenient to make a space than double tap the sceen to make a period. Unexpected results are likely to occur. For example, attempting to lookup HgS as hgs will lookup H, then try to find G, then try to find Gs. Numbers are allowed as they would normally be entered. If used with periods, the number must precede the next period.
Numbers can be any non-negative real number.
I had great difficulty in imagining why anyone would use imaginary numbers. Parenthesis may be used in the molecular formula. This allows for easier entering of formulas. Nested parenthesis are allowed, but all parenthesis must be matched. This is perfectly acceptable, but will not increase the accuracy or the speed of the program.