Have a look at the video below:
Dual nature of electrons
So Electrons can behave as particles and also as WAVES…
Here you have some details about WAVES we need to know:
Waves Notes: PowerPoint Presentation (PPT format)
Waves exercises:
waves of visible light can be represented as follows:

Waves Exercises: Worksheet and exercises (PDF format)
LAB : FLAME TEST (PDF) (DUE ONE DAY AFTER THE LAB)
Links to see the line spectra of the elements:
http://student.fizika.org/~nnctc/spectra.htm
http://profmokeur.ca/chemistry/spectemien.htm