Consider the 10 most abundant elements in Earth’s crust, listed from most to least abundant: Oxygen, Silicon, Aluminum, Iron, Calcium, Sodium, Magnesium, Potassium, Titanium, Hydrogen For each element other than iron, draw the corresponding orbital configurations and indicate the number of protons and neutrons in the nucleus of the most abundant isotope. Group electrons in the principal shells (i.e., 1, 2, 3, 4; note shells 1-4 are labeled alphabetically as K, L, M and N in x-ray notation). You can ignore the subshells (i.e., s, p, d, f). Iron is shown as an example: The orbital configuration is 1s22s22p63s23p64s23d6, so there are two electrons in the first shell (K), 2+6=8 electrons in the second shell (L), 2+6+6=14 electrons in the third shell (M), and two electrons in the fourth shell (N). The atomic number is 26, so there are 26 protons (and electrons). The atomic mass is 55.85, so we round that up to 56; this is also the mass number of the most abundant isotope, which means there are 56-26=30 neutrons.

Fig: 1