Question 254501

1. After the discovery of protons and electrons, it was noticed that there was trend in the periodic table. Helium weighs ~4 and is atomic number 2, Carbon weights ~12 and has atomic number 6. Heavier elements can weigh more than double the atomic number (i.e., gold: atomic mass = 197, atomic number = 79, while for hydrogen atomic mass = 1, atomic number = 1.) How can we best explain this deviation in the trend?