Answer:
See below.
Step-by-step explanation:
The behavior of elements with respect to their radius and ionization energy may appear, at first, to be a matter of mindless memorization. But there is a method to the madness that allows one to use the organization of the periodic table to answer these questions with only a few key principles.
Atomic Radius
The attached graphic (PerTableRadiusTrend) illustrates the trend in atomic radius. Contrary to expectations, the radius of the elements INCREASES from left to right. Wait - the mass of these elements is increasing from left to right, so why are they shrinking? Each increase in atomic number adds an additional proton to the nucleus, which increases the positive charge in the nucleus by +1. The increased electrostatic forces draw the electrons closer to the nucleus. They don't get to the nucleus because they repel each other. Instead, they settle into defined orbitals where the balance of the charges keep the element in a stable, but condensed, shape.
When one goes down the table, we see an expected increase in radius as the elements continues to add protons. The big difference in each row is the addition of a new energy shell that has another set of orbitals that are further out from the nucleus. For example, the radius of fluorine, F, near the end of row 2, has a radius of 50 pm (picometers), while that of
sodium, Na, at the start of row 3 is 180pm!
Use this understanding to predict the order in which the elements are arranged according to atomic radius:
N, F, Li: These are all on the 2nd row of the table. So order them from smallest atomic number to highest, which should also put them in order of decreasing atomic radius:
Li, N, F smallest to largest radius
The actual radius for each is 145, 65, and 50 picometers (10^-12 meters)
Br, F, I: These elements are on different rows, but same column on the table. Their radius should increase as we go down the table. Thjis would mean:
F, Br, I smallest to largest radius
1st Ionization Energy
Ionization energy refers to the amount of energy it takes to remove an electron from an element. Electrons are attracted to the nucleus they orbit, so there needs to be some reason for them to leave. Ionization energy tells us how much energy it would take. A low ionization energy means it won't take much to remove an electron. See the attached graphic for ionization energy trends. Ionization energies increase from left to right, and decreases from top to bottom.
See attached graphic PerTableIonization.
When one move across the table, new orbitals are added to handle the electrons. An element to the far right has all it's orbitals filled for that energy level. An element that has all its orbitals filled for each energy level exists in a stable, low energy, condition. That is true for all the elements on the far right (Ne, Ar, Kr, etc.). They are very stable and resist any change to their electron orbials. The elements to the immediate left (F, Cl, Br, etc.) are one electron short of a full shell. They will steal electrons from other elements, given the chance (sometimes violently). So the have a very high ionization energy. They resist giving up electrons. Elements on the far left (Li, Na, K, etc.) have one lone electron in a new energy level. It is pretty far from the nucleus, and can be coaxed off relatively easily. They are said to have low ionization energies. They will VERY happily shed their lonely electron to other elements. Some popular outcomes are NaCl (salt), H2O, KBr, HCl, etc.
The term valence electrons is used to describe the electons in the outermost energy level. The valence shell is where the action is when it comes to bonding with other elements. Atoms will tend to seek lower energy conditions. This is often the reason atoms combine. As an example, sodium and chlorine atoms are in a situation. Sodium (Na) has a single electron in the next energy level for that atom. Chlorine has one last empty position in it highest energy level orbital. Chlorine will tend to steal electrons to fill that last, empty, spot. That will put the chloine atom atom in a lower energy state. Sodium is very happy to provide that 1 electron, since it would then have all its electrons in lower energy orbitals.
Use this information and the table to determine the correct order of electronegativities:
From lowest to highest
Ne, F, C: C, F, Ne
Mg, Sr, Be: Sr, Mg, Be
Sn, S, As: Sn, As, S
The same principles can be used to adress electron affinity. This refers to the attraction an element has to add electrons. We know that elements to the far right would love to add elelctrons to fill their last orbitals in their energy level. The nobel gases all have full other shells, and are very stable becuse of it.