On the periodic table, which element listed below is expected to behave most like magnesium in its chemical properties?

Introduction / Context:
This question tests your understanding of periodic trends and group similarities. Elements in the same group of the periodic table have similar valence electron configurations and therefore show similar chemical behaviour, such as forming ions of the same charge and combining with other elements in analogous ways. Magnesium is a group 2 alkaline earth metal, and you are asked to identify which element among the options will behave most like magnesium.

Given Data / Assumptions:

• Magnesium is located in group 2 (the alkaline earth metals).
• The options include Sr, S, Si, Sn and Cl.
• We are comparing general chemical behaviour such as typical oxidation states and bonding patterns.
• Standard periodic table positions and group trends are assumed.

Concept / Approach:
Elements in the same group share the same number of valence electrons. Magnesium has an electron configuration ending in 3s2 and belongs to group 2. Strontium also lies in group 2 with a valence configuration ending in 5s2. Both typically form +2 cations (Mg2+ and Sr2+) and show similar reactivity with water, acids and halogens. In contrast, sulfur, silicon, tin and chlorine belong to other groups and have different valence electron counts, leading to different typical oxidation states and bonding patterns. Therefore, the element that behaves most like magnesium is the one directly below it in the same group: strontium.

Step-by-Step Solution:
Step 1: Identify the group of magnesium. It is in group 2, the alkaline earth metals. Step 2: Recall that elements in the same group have identical valence electron configurations and similar chemical properties. Step 3: Locate strontium (Sr) in the periodic table; it is also in group 2, below calcium and magnesium. Step 4: Note that Sr, like Mg, typically forms a +2 ion and reacts with acids and water to form Sr2+ and hydrogen gas. Step 5: Consider sulfur (S), which is a group 16 nonmetal and usually forms −2 anions or covalent compounds, unlike magnesium. Step 6: Silicon (Si) is a group 14 metalloid with a valence of 4, and tin (Sn) is a group 14 metal that commonly shows +2 and +4 oxidation states, not the simple +2 of magnesium in the same way. Step 7: Chlorine (Cl) is a group 17 halogen, typically forming Cl− ions and covalent molecules, very different from magnesium.

Verification / Alternative check:
You can further verify this by comparing chemical reactions. Magnesium reacts with hydrochloric acid to form magnesium chloride and hydrogen; strontium behaves similarly, forming strontium chloride and hydrogen. Both metals react with oxygen to form oxides of the form MO, where M is the metal, and with halogens to form ionic halides MX2. Their hydroxides are basic and show similar solubility trends. By contrast, sulfur forms oxides like SO2 and SO3 and acidic oxoacids, silicon forms covalent network solids such as silica and tin forms more complex metallic and covalent compounds. These patterns confirm that strontium behaviour parallels magnesium most closely.

Why Other Options Are Wrong:
Sulfur is chemically very different from magnesium because it is a nonmetal and forms negative ions or covalent compounds, not simple +2 metal ions. Silicon is a metalloid involved in covalent network structures and does not mimic the behaviour of alkaline earth metals. Tin, though a metal, belongs to a different group and has different common oxidation states and bonding. Chlorine is a halogen, strongly electronegative and typically forms negative ions or covalent molecules like Cl2, again very unlike magnesium. Hence, none of these elements behaves as closely like magnesium as strontium does.

Common Pitfalls:
A common error is to pick any metal or any element near magnesium on the periodic table without checking the group number. Some students confuse periods (rows) with groups (columns), assuming that elements in the same period behave similarly. While there are periodic trends, chemical behaviour is far more strongly tied to group membership. To avoid such mistakes, always identify the group of the reference element and choose an option from the same group when asked which element behaves most similarly.

Final Answer:
The element that behaves most like magnesium is strontium (Sr), another group 2 alkaline earth metal.