Question

unit 4: periodic trends
directions: answer each question completely. indicate how you determined the answer to each question below.

1. draw two separate arrows indicating the direction of increasing atomic size for the period and group trends.
2. draw two separate arrows indicating the direction of increasing ionization energy for the period and group trends.
3. why does a cation decrease in size?
4. which element is the most electronegative? what does that mean it would do when forming a bond?

Explanation:

1. Atomic size increases down a group (more electron shells) and decreases across a period (higher nuclear charge pulls electrons closer).
2. Ionization energy increases across a period (higher nuclear charge) and decreases down a group (electrons are farther from the nucleus).
3. A cation loses electrons, reducing electron-electron repulsion and often removing an entire electron shell, so the remaining electrons are pulled closer to the nucleus.
4. Fluorine is the most electronegative element; it attracts bonding electrons strongly, often gaining electrons to form negative ions.

Answer:

1. Period trend: Arrow from right to left; Group trend: Arrow from top to bottom (on the periodic table outline).
2. Period trend: Arrow from left to right; Group trend: Arrow from bottom to top (on the periodic table outline).
3. Loss of electrons reduces repulsion and may remove a shell, shrinking the ion.
4. Fluorine; it strongly attracts bonding electrons.