Key Differences:
* State of Matter: Many ionic compounds are solid at room temperature, while the elements that make them up can be solids, liquids, or gases. For example, sodium (Na) is a soft, silvery metal, and chlorine (Cl) is a greenish-yellow gas, but sodium chloride (NaCl) is a white, crystalline solid (table salt).
* Melting and Boiling Points: Ionic compounds generally have high melting and boiling points due to the strong electrostatic forces holding the ions together. In contrast, the elements that make them up usually have much lower melting and boiling points.
* Electrical Conductivity: Ionic compounds conduct electricity when dissolved in water or melted. This is because the ions are free to move and carry charge. The elements that make them up are often poor conductors of electricity in their elemental form.
* Solubility: Ionic compounds have varying solubility in different solvents, often dissolving in polar solvents like water. The elements that make them up may have different solubility patterns.
* Brittleness: Ionic compounds are often brittle, meaning they break easily under pressure. The elements that make them up may be more malleable or ductile.
Why the Difference?
The significant difference in properties arises from the nature of ionic bonding. In ionic compounds, atoms gain or lose electrons, forming charged ions. These ions are held together by strong electrostatic attractions. This strong attraction creates a rigid, crystalline structure with high melting and boiling points.
Example:
Consider sodium chloride (NaCl):
* Sodium (Na) readily loses an electron to form a positive ion (Na+).
* Chlorine (Cl) readily gains an electron to form a negative ion (Cl-).
* The oppositely charged ions attract each other strongly, forming a crystalline structure with high melting and boiling points.
In Summary:
Ionic bonding leads to significant changes in physical and chemical properties compared to the individual elements that make up the compound.
