Ca (1st isotope) number Z is 40

# P Ca - 2 neutral 5 ending, 6 first C nuclet, 6 2nd  C nuclet, 2 * 3 Li nuclets totaling 2 + 6 + 6 + 2*3 = 20

# N Ca - 3 neutral 5 ending, 6 first C nuclet, 5 2nd C nuclet, 2 * 3 Li nuclets totaling 3 + 6 + 5 + 2*3 = 20