From left to right on the periodic table, atomic radius decreases because the number of protons increase while electrons are being added to the same shell; the attraction between the nucleus and the electron cloud override the shielding effect of adding electrons to the same shell. Therefore, those on the left are larger. From top to bottom on the periodic table, atomic radius/size increases because electrons are added to new valence shells significantly further from the nucleus than the previous shell. Therefore, those on the bottom left are largest.

From left to right on the periodic table, atomic radius decreases because the number of protons increase while electrons are being added to the same shell; the attraction between the nucleus and the electron cloud override the shielding effect of adding electrons to the same shell. Therefore, those on the left are larger. From top to bottom on the periodic table, atomic radius/size increases because electrons are added to new valence shells significantly further from the nucleus than the previous shell. Therefore, those on the bottom left are largest. Sulfur is the largest since it is in period 3. The remaining atoms are in period 2, with lithium being the largest, followed by nitrogen, oxygen, and fluorine.

The tendency to lose an electron is related to ionization energy, which is principally the opposite of electronegativity. The higher the ionization energy, the harder it is to pull an electron from the atom (takes more energy to ionize). Elements on the right side of the periodic table have higher ionization energies because they tend to gain electrons to achieve a full valence electron shell rather than lose them. Elements on the left side of the periodic table have lower ionization energies because they tend to lose electrons in their valence shell to achieve a full shell. Alkali metals need to lose 1 electron to achieve noble gas electron configuration, whereas the first electron lost from an alkaline earth metal does not confer this stability.

Halogens have seven electrons in their valence shell, so they only need one more electron to obtain a completely filled valence shell. In addition, the unpaired electron in the seven electron shell is a radical which is highly reactive.

While noble gases are very stable due to their filled octet, they actually do take place in certain reactions, so that is not a property of noble gases. All other answer choices are true.

We know that element Z is magnesium due to its jump bwtween ionization energies 2 and 3. Magnesium is in the second group of the periodic table and shares similar chemical properties with other alkali earth metals, such as strontium.

Sodium is an alkali metal. All alkali metals are found in group 1 on the periodic table, and lose 1 electron in order to achieve a stable octet. Any ion that loses an electron, and thus becomes positively charged, is referred to as a cation. Anions are negatively charged ions, so sodium is not going to become an anion.

We know element X is sodium due to its discrepancy between IE₁ and IE₂. Sodium has one valence electron and is an alkali metal. Pure alkali metals react violently with water. The heavier the metal, the bigger the explosion. 

This is the definition of gamma radiation.

During alpha decay, an element emits a helium nucleus with 2 neutrons and 2 protons. Thus, the atomic mass of the new element is decreased by four, and the atomic number is decreased by two.

Three subsequent alpha decays result in a new element with an atomic mass of 232 - 3(4) = 220, and a new atomic number of 90 - 3(2) = 84.

Using the periodic table, we find the element with this atomic number is polonium (Po).