Question

11.rank the following elements by decreasing atomic radius: zinc, vanadium, titanium, selenium, calcium
12.describe the trend for atomic radius as you move from top to bottom within a group on the periodic table. why is this the case?
13.describe the trend for atomic radius as you move from left to right within a period on the periodic table. why is this the case?

Explanation:

Step1: Recall atomic - radius trends

Atomic radius decreases across a period (left - to - right) and increases down a group. Calcium (Ca), vanadium (V), titanium (Ti), zinc (Zn) are in period 4 and selenium (Se) is in period 4 too. In period 4, elements are arranged as Ca (Group 2), Sc (Group 3), Ti (Group 4), V (Group 5),..., Zn (Group 12), Se (Group 16).

Step2: Rank elements in period 4

Since atomic radius decreases from left to right in a period, the order of decreasing atomic radius for Ca, V, Ti, Zn, Se is Ca > V > Ti > Zn > Se.

Step3: Trend in a group

As you move from top to bottom within a group on the periodic table, the atomic radius increases. This is because new electron shells are added as you go down a group. Each new shell is farther from the nucleus, increasing the distance from the nucleus to the outermost electrons, thus increasing the atomic radius.

Step4: Trend in a period

As you move from left to right within a period on the periodic table, the atomic radius decreases. This is because the number of protons in the nucleus increases (increasing the nuclear charge) while the electrons are added to the same shell. The increased nuclear charge pulls the electrons closer to the nucleus, reducing the atomic radius.

Answer:

1. Calcium > Vanadium > Titanium > Zinc > Selenium
2. The atomic radius increases as you move from top to bottom within a group. This is because new electron shells are added, increasing the distance from the nucleus to the outermost electrons.
3. The atomic radius decreases as you move from left to right within a period. This is due to the increasing nuclear charge pulling the electrons in the same shell closer to the nucleus.