Which of the following elements in the third period of the periodic table typically forms a cation with a +1 charge?

• A. Al
• B. Na
• C. Si
• D. Mg

Answer: (B)

Verified step by step guidance

1. Identify the elements listed and their positions in the third period of the periodic table: Al (Aluminum), Na (Sodium), Si (Silicon), and Mg (Magnesium).
2. Recall that elements in the third period have electrons filling the 3s and 3p orbitals, and their typical charges as ions depend on their tendency to lose or gain electrons to achieve a stable noble gas configuration.
3. Understand that alkali metals (Group 1 elements) like Sodium (Na) typically lose one electron to form a +1 cation because they have one electron in their outermost shell.
4. Recognize that Magnesium (Mg), an alkaline earth metal (Group 2), typically forms a +2 cation by losing two electrons, Aluminum (Al) typically forms a +3 cation, and Silicon (Si), a metalloid, usually does not form a simple +1 cation.
5. Conclude that among the given options, Sodium (Na) is the element in the third period that typically forms a cation with a +1 charge.