9.84 * 10^-4
The easiest way I remember is making the decimal first and then seeing what way the 0's are. In this case it is going left so it will be a negative exponent and if you count from 9.84 and move the decimal left 4 that's your answer.
Answer:
Aluminum atomic number= 13
electron configuration = 2, 8 , 3
Hope it helps...........
