Final answer:
Properties of elements that visibly show periodic trends when their values are graphed include atomic size, ionization energy, and electron affinity.
Step-by-step explanation:
The properties of elements that visibly show periodic trends when their values are graphed include atomic size, ionization energy, and electron affinity.
Atomic size, or atomic radius, generally increases as you move down a group (vertical column) in the periodic table. This is because additional energy levels or electron shells are added as you move down, resulting in larger atomic size.
On the other hand, ionization energy, which is the energy required to remove an electron from an atom, generally increases as you move across a period (horizontal row) from left to right in the periodic table. This is because the atomic size decreases and the attraction between the positively charged nucleus and the negatively charged electron increases, making it more difficult to remove an electron.
Lastly, electron affinity, which is the energy change when an atom gains an electron, also shows periodic trends. Electron affinity generally becomes more negative (increases) as you move across a period from left to right, except for a few exceptions. This is because atoms on the right side of the periodic table have a higher effective nuclear charge, which makes it easier for them to attract and gain electrons.