Respuesta :

  equation  is   balanced  when  the  number  of  molecules     are  the  equal  in  both  reacting  side  and  the  product side.
Li(s)  +  n2(g) ---> Li3n(s)
From   the  equation  above  the  reaction  is not  balanced  since    the  molecules  are  not  equal  in  both  reacting  side  and  the  product   side.

The reaction  is  balanced   by  adding   6  in  front  of  Li  and  2  infront  of  Li3n
  that  is
 6Li(s)  + n2(g)----->  2Li3n(s)

W0lf93
The balanced equation would be 6 Li + N2 --->2 Li3N 
Li, Lithium is solid reacts with the gas N to give the solid compound Li3N.
 There are a total of 6 lithium ions, 2 nitrogen ions. This reaction is called as combination reaction as the two elements react and form single compound. 
Li, Lithium is solid reacts with the gas N to give the solid compound Li3N.