Answer:
2 valence electrons.
Step-by-step explanation:
Valence electrons are the sum total of all the electrons in the highest energy level (principal quantum number n). Most transition metals have an electron configuration that is 
n 
s 
2 
( 
n 
− 
1 
) 
d 
, so those 
n 
s 
2 
 electrons are the valence electrons