Final answer:
The elements ranked in order of decreasing ionization energy are Oxygen, Carbon, Silicon, Magnesium, and Calcium.
Step-by-step explanation:
Ionization energy is the amount of energy required to remove an electron from an atom or ion. In general, ionization energy increases from left to right across a period and decreases from top to bottom within a group on the periodic table.
Ranking the elements in order of decreasing ionization energy:
- Oxygen: Oxygen has the highest ionization energy because it is located in the top right corner of the periodic table.
- Carbon: Carbon is located to the left of oxygen and has a slightly lower ionization energy.
- Silicon: Silicon is located below carbon and has a lower ionization energy compared to carbon.
- Magnesium: Magnesium is located to the left of silicon and has a lower ionization energy compared to silicon.
- Calcium: Calcium is located below magnesium and has the lowest ionization energy among the given elements.