Compounds

• Compounds play a significant role in our daily life, appearing in food, air, cleaning chemicals, and virtually every object we can see or touch.
• Compounds are made up of elements that are chemically bonded by electrostatic forces.
• Compounds can be classified as ionic or covalent.
• An ionic compound is formed when a metal (cation) transfers its valence electron/s to a nonmetal (anion).
• The covalent compound is formed when nonmetals share their valence electrons with another nonmetal.
• The formation of ionic and covalent compounds can be illustrated by an element transferring or sharing their valence electrons to attain stability.
• Ionic and covalent compounds can be identified and described through their chemical formula and name by observing the types of elements involved in a compound.
• In chemistry, the chemical formula is a symbolic expression signifying the number of atoms present in a molecular substance.
• The type of atom in a compound can be determined by referring to its chemical symbol.
• The number of atoms in a compound is determined by the subscript attached to the symbol.
• Chemical name shows the name of each element involved in a compound.
• Carbon dioxide, chemical formula written as C𝑂2, is an example of a covalent compound, since the elements involved are nonmetals, namely, one carbon atom and two oxygen atoms.
• Sodium chloride, chemical formula written as NaCl, is an example of an ionic compound, since the elements involved are sodium (Na) a metal and chlorine (Cl) a nonmetal.
• At normal atmospheric pressure and temperature, covalent compounds may exist in solid, liquid, or a gas, while ionic compounds exist only as crystalline solids.
• In covalent compounds, electrons are shared and no full ionic charges are formed, which makes the molecules in this compound not strongly attracted to one another compared to ionic compounds.
• Covalent molecules move freely and tend to exist as liquid or gas at room temperature like alcohol, which is widely used as a disinfectant, fuel, and as a main component of alcoholic beverages.
• Most ionic compounds do not actually exist as molecules; instead, the ions are arranged in an alternating positive and negative ion bonded together in a matrix.
• The ions in ionic compounds are held rigidly together in their crystal lattice structure, which is why they are solid under normal atmospheric pressure and temperature, like for example sodium chloride (NaCl), which is commonly used for flavoring and preserving foods.
• Ionic compounds generally have higher melting and boiling points while covalent compounds have lower melting and boiling points.
• Ionic compounds have high melting and boiling point because it takes a lot of thermal energy for ions (charged atoms) in the crystal to separate them apart from each other.
• Covalent compounds have low melting and boiling point because of the weak force of attraction between molecules.
• A small amount of thermal energy can separate covalent compounds.
• Ionic compounds are usually soluble in water, while covalent compounds tend to be less soluble in water.
• Solubility is the ability of a substance that may exist in solid, liquid, or gas form, referred to as the solute, to dissolve in solvent.
• Many ionic compounds are highly soluble in water because water molecules, a polar solvent, attract each of the ions of an ionic compound and pull the ions away from one another.
• Ionic compounds are less soluble in solvents that contain a common ion.
• Some covalent compounds are not soluble in water: they do not dissolve well in water.
• Compounds that have similar properties, particularly polarity, tend to dissolve in each other.
• Ionic compounds are generally less flammable than covalent compounds due to the presence of water in covalent compounds.
• The concept of "Like dissolves like" is often expressed.
• Combustion happens when substances containing carbon and hydrogen react with oxygen gas, forming carbon dioxide (C𝑂2) and water (𝐻2 𝑂).
• For substances with unlike polarities, like water and oil, where water is polar and oil is nonpolar, these two substances are insoluble with each other.
• Organic compounds, which are mostly found together in covalent compounds, burn because they contain carbon and hydrogen.
• More covalent compounds tend to be more flammable than ionic compounds.
• Not all covalent compounds burn, for instance, water, a covalent, has a molecule that is bonded with a polar covalent, making it hard to start fire with it.
• Liquefied Petroleum Gas (LPG) is an example of a covalent compound that contains a flammable mixture of hydrocarbon (hydrogen and carbon) gases.
• Liquefied Petroleum Gas (LPG) is usually used as fuel in cooking equipment, heating appliances, and vehicles.
• The flammability property of Liquefied Petroleum Gas (LPG) requires all the liquefied petroleum gas (LPG) industry participants to observe the minimum safety standards in the transportation and distribution of the petroleum product in cylinders under the mandated order of the Department of Energy (DOE), stated in their department circular (DC) 2014-01-0001 or the “The LPG Industry Rules”.
• Ionic compounds conduct heat and electricity compared to covalent compounds.
• In a chemical bond, ionic compounds are generally considered a good conductor of electricity when dissolved or in an aqueous solution.