Periodic Table trends for atomic number and valence electrons

Steps:

• Identify atomic numbers (proton numbers): Li = 3, Ca = 20, Cl = 17; Ca is highest.
• Identify groups to find valence electrons: Li in group 1 (1 electron), Ca in group 2 (2 electrons), Cl in group 17 (7 electrons); Cl is highest.
• Compare: Highest proton number is Ca; largest valence electrons is Cl.

Why B is correct:

• Atomic number defines proton count, increasing across periods; valence electrons equal group number for main-group elements (IA-VIIA), so Ca (20 protons, group 2) and Cl (17 protons, group 17 with 7 valence electrons) match.

Why the others are wrong:

• A: Cl has 7 valence electrons, more than Ca's 2.
• C: Li has only 3 protons, not highest.
• D: Li has only 3 protons, not highest.

Final answer: B