Element \(\mathrm{X}\) forms a chloride with the formula \(\mathrm{XCl}_{2}\), which is a solid with a high melting point. X would most likely be in the same group of the Periodic Table as (a) \(\mathrm{Na}\) (b) \(\mathrm{Mg}\) (c) AI (d) Si

Valence electrons are the electrons located in the outermost shell of an atom. They play a key role in determining how an element will react chemically with other substances. For example, in the exercise involving element \(\text{X}\) forming \(\text{XCl}_2\), the subscript '2' in \(\text{XCl}_2\) tells us that two chlorine atoms are bonding with element X. This means X has two valence electrons available for bonding. Understanding the concept of valence electrons is crucial because:

• It helps predict the types of chemical bonds that an element can form.
• It aids in determining the element's placement in the Periodic Table, specifically its group number.

In the Periodic Table, elements in the same group have the same number of valence electrons, which is why they exhibit similar chemical properties. For instance, all Group 2 elements have two valence electrons, making them reactive but less so than Group 1 elements.

Alkaline earth metals constitute Group 2 of the Periodic Table. They include elements like Beryllium (\text{Be}), Magnesium (\text{Mg}), Calcium (\text{Ca}), Strontium (\text{Sr}), Barium (\text{Ba}), and Radium (\text{Ra}). These metals are known for having two valence electrons. This explains why a compound like \(\text{XCl}_2\) would likely be formed by an alkaline earth metal. Some key attributes of alkaline earth metals include:

• They are all shiny and silvery-white.
• They have higher melting points compared to Group 1 metals.
• They react with water, though not as vigorously as Group 1 metals.
• They are good conductors of electricity.

In the step-by-step solution, we see that \(\text{X}\) is most likely magnesium (\text{Mg}), an alkaline earth metal known for forming stable chlorides like \(\text{MgCl}_2\), which has a high melting point.

Chemical bonding is the process through which atoms combine to form compounds. There are primarily three types: ionic, covalent, and metallic bonds. In the exercise example, element \(\text{X}\) forms \(\text{XCl}_2\), which indicates ionic bonding. This is common among alkaline earth metals, which tend to lose their two valence electrons easily to achieve a stable electron configuration. Key points about ionic bonding include:

• Ionic bonds form between metals and non-metals.
• Metals tend to donate electrons, becoming positively charged cations.
• Non-metals accept electrons, becoming negatively charged anions.
• The electrostatic attraction between cations and anions forms a strong bond.

In the compound \(\text{XCl}_2\), the metal \(\text{X}\) donates its two valence electrons, one to each chlorine atom. Chlorine (\text{Cl}), a non-metal with seven valence electrons, accepts the electron to fulfill its octet, forming a stable ionic compound with high melting points and solid states, characteristic of such bonds.