Question

write the chemical symbol for an element in period 6 and group 3a.

Explanation:

Step1: Recall Periodic Table Structure

In the periodic table, period number corresponds to the principal quantum number (n) of the outermost electrons, and group number (for main - group elements) indicates the number of valence electrons. Group 3A elements have 3 valence electrons, and period 6 means the outermost electrons are in the 6th energy level.

Step2: Identify the Element

The element in period 6 and group 3A is Thallium? No, wait, Thallium is in group 13 (which is 3A in the old numbering) and period 6? Wait, no, let's check the periodic table. The elements in group 3A (group 13) and period 6: The atomic number progression. Let's list the elements in group 13: Boron (B, period 2), Aluminum (Al, period 3), Gallium (Ga, period 4), Indium (In, period 5), Thallium (Tl, period 6). Yes, Thallium (Tl) is in period 6 and group 13 (3A).

Answer:

$\text{Tl}$