Use the periodic table to compare the sizes of ionic radii with the corresponding atomic radii or other ionic radii. Choose from smaller and larger in the blanks below:
A sodium cation is
than a sodium atom.
A phosphorus anion is
than a phosphorus atom.
A magnesium ion is
than a sodium ion.
A chlorine ion is
than a phosphorus ion.
A potassium ion is
than a sodium ion.

1. smaller

2.smaller

3.larger

4.larger

5.smaller

 2. ... its Larger. because The extra electrons add to the volume of the atom. Since they're just filling in levels that are already partially filled, it isn't by much, but they do push on the other electrons by way of their charge, decreasing the density of the 3-minus ion relative to that of the neutral atom.5.Na+ ions are smaller than K+ ions because K+ ions are farther down the periodic table, which causes atomic radius to increase because the strength of the bonds decreases (there are more elementary particles to attract, i.e. electrons, protons, neutrons), and they become more spread out. Also, K+ has more protons than Na+ ions.   so yeah thats how i got my answer ever thou i got number 2 wrong 

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6