Question

What is the PEL of Valence Electrons of the elements, Li, Mg, Cl, I, Ga, Kr, Na, and Te?

Answer 1

Looking at the periodic table, the first period (H, He) has valence electrons at n = 1.

The second period has valence electrons at n = 2. etc.

Thus for Li it is 2; Na, Mg, Cl it is 3; Ga, Kr it is 4; I, Te it is 5.

This rule only applies to representative elements (All of these elements are representative elements) So we do not consider outer electrons in completely filled d or f subshells to be valence electrons.

For transition metals it is different, outer electrons in a completely filled f subshell shouldn't be considered as valence electrons. But those in the d subshell can be. For example, for cobalt, it has 9 valence electrons, 7 in

n = 3 and 2 in n = 4. the valence electrons are in two different energy levels.

Answer 2

The PEL of valence electrons for each element corresponds to the period number they are in on the periodic table. Li, Mg, and Na have their valence electrons in the 2nd PEL; Cl and Kr in the 3rd PEL; I and Te in the 5th PEL; and Ga in the 4th PEL.

Step-by-step explanation:

The Principal Energy Level (PEL) of valence electrons for the elements Li, Mg, Cl, I, Ga, Kr, Na, and Te can be determined using their positions on the periodic table. To find the PEL, you look at the period (horizontal row) that the element is in, which corresponds to the primary energy level that the outermost electrons occupy.

• Lithium (Li) is in period 2, so its valence electrons are in the 2nd PEL.
• Magnesium (Mg) is also in period 2, so its valence electrons are in the 2nd PEL.
• Chlorine (Cl) is in period 3, indicating the 3rd PEL for its valence electrons.
• Iodine (I) is in period 5, therefore its valence electrons are in the 5th PEL.
• Gallium (Ga) is in period 4, so its valence electrons are in the 4th PEL.
• Krypton (Kr) is in period 4 as well, placing its valence electrons in the 4th PEL since it's a noble gas.
• Sodium (Na) is in period 3, so its valence electrons are in the 3rd PEL.
• Tellurium (Te) is in period 5, indicating the 5th PEL for its valence electrons.

Remember, the group number (except for transition metals) can also help identify the number of valence electrons. However, for this question, only the PEL of valence electrons is queried.