Final answer:
The elements carbon (C), nitrogen (N), and oxygen (O) are arranged in order of increasing ionization energies as carbon first, followed by nitrogen and then oxygen, due to their positions in the periodic table and the effective nuclear charge each possesses.
Step-by-step explanation:
The correct order, when arranging the elements carbon (C), nitrogen (N), and oxygen (O) in order of increasing ionization energies, is carbon, nitrogen, and then oxygen. This order is understandable through the concept of effective nuclear charge and electron configuration.
Carbon, being in Group 14, has four valence electrons and a lower effective nuclear charge compared to oxygen and nitrogen. It requires less energy to remove an electron from carbon. Nitrogen, in Group 15, has a higher nuclear charge than carbon, but less than oxygen. Although nitrogen has half-filled p orbitals which are relatively stable, its ionization energy is still higher than that of carbon. Oxygen, present in Group 16, has a higher effective nuclear charge due to its increased number of protons, and closely packed electrons experience more repulsion, causing a slight decrease in ionization energy as compared to nitrogen; however, it still requires more energy to remove an electron from oxygen than from carbon or nitrogen.
Therefore, the order of elements from lowest to highest ionization energy is C < N < O.