Worksheet titled "Periodic Trends Worksheet" featuring questions about atomic and ionic radius, including comparisons of elements and definitions of ions.

1. a) K b) Ca c) Ga d) C e) Br f) Ba g) Si h) Au
2. Atomic size increases from top to bottom in a group. Atomic size decreases from left to right in a period.
3. Atoms get smaller moving left to right in a period because the number of protons increases, pulling electrons closer to the nucleus with greater effective nuclear charge, while electrons are added to the same principal energy level.
4. Atoms get larger moving down a group because each successive element has an additional electron shell (principal energy level), increasing the distance between the nucleus and the outermost electrons, despite the increase in nuclear charge.
5. Ar < P < Si < Mg < Na
6. An ion is an atom or molecule that has gained or lost one or more electrons, resulting in a net positive or negative electrical charge.
7. A cation is a positively charged ion formed by losing electrons; an anion is a negatively charged ion formed by gaining electrons.
8. Cations are smaller than their parent atoms because they lose electrons, reducing electron-electron repulsion and often losing an entire electron shell. Anions are larger than their parent atoms because they gain electrons, increasing electron-electron repulsion and sometimes adding to the same shell without increasing nuclear charge proportionally.
9. a) Na b) S²⁻ c) I⁻ d) Al
10. E) O²⁻, F⁻, Ne, Na⁺