Chemical compounds consist of multiple homologous molecules comprised of atoms derived from multiple elements that are interconnected through chemical bonding. There exist four distinct types of compounds, which are categorized based on how the constituent atoms are bound together.
- Molecules are bound together through the formation of covalent bonds.
- Ionic compounds are formed through the bonding of ions, resulting in the establishment of ionic bonds.
- Intermetallic compounds are cohesive due to the presence of metallic bonds.
- The formation of specific complexes is facilitated by the presence of coordinate covalent bonds.
A chemical formula serves as a means of communicating details regarding the constituent atoms of a specific chemical compound. This is achieved through the utilization of standardized abbreviations for chemical elements, along with subscripts to indicate the number of atoms present. As an example, water consists of two hydrogen atoms that are bonded to one oxygen atom, denoted by the chemical formula H₂O. The Chemical Abstracts Service (CAS) assigns a unique numerical identifier to various chemical compounds.
The alteration of a compound’s chemical conformation can be achieved through a chemical reaction that occurs when it interacts with a second chemical compound. This method involves the dissociation of chemical bonds in both interacting compounds, followed by the reformation of bonds to establish new connections between atoms.
- A chemical compound can be defined as any substance that consists of two or more distinct types of atoms, or chemical elements, in a specific and unchanging stoichiometric ratio. This concept is most easily comprehended when examining chemically pure substances. The inherent composition of chemical compounds, consisting of a constant proportion of two or more types of atoms, allows for their conversion into compounds or materials with a reduced number of atoms through a chemical reaction.
- The elemental composition of a compound is denoted by its chemical formula. A chemical formula serves as a means of conveying pertinent details regarding the constituent atoms of a particular chemical compound. It employs established abbreviations for chemical elements and subscripts to indicate the number of atoms involved.
- For instance, the chemical compound H2O stands for water, which consists of two hydrogen atoms bound to one oxygen atom. In the case of non-stoichiometric compounds exemplified, it is possible to observe a consistent ratio during their production, resulting in a fixed proportion of their constituent elements. However, it should be noted that these proportions are not crucial or indispensable.
e.g. palladium hydride [PdHx (0.02 < x < 0.58) ℎ (0.02 < x < 0.58)]
- Chemical compounds consist of distinct and well-defined chemical configurations that are interconnected through chemical bonds, forming a precise three-dimensional arrangement.
- Chemical compounds can be classified into various categories based on the type of bonding that holds their constituent atoms together.
- These categories include molecular compounds, which are characterized by covalent bonds; salts, which are characterized by ionic bonds; intermetallic compounds, which are characterized by metallic bonds; and a subset of chemical complexes, which are characterized by coordinate covalent bonds.
- Chemical elements in their pure state are typically not classified as chemical compounds, as they do not meet the criterion of consisting of two or more atoms. However, it is worth noting that they frequently comprise molecules composed of multiple atoms.
- The Chemical Abstracts Service (CAS) assigns a unique numerical identifier to various chemical compounds.
Types of Chemical Compounds
- Molecular compounds are interconnected through the formation of covalent bonds.
- A molecule refers to an electrically neutral assembly of two or more atoms that are interconnected through chemical bonds. The distinction between molecules and ions lies in their respective electrical charges, with molecules being characterized by their absence of charge. However, within the domains of quantum organic chemistry, physics, and biochemistry, the term “molecule” is frequently employed in a broader sense, encompassing polyatomic ions that consist of multiple atoms.
- Within the framework of the kinetic theory of gases, the term “molecule” is frequently employed to refer to a gaseous entity, irrespective of its composition. Based on the provided definition, noble gas atoms are conceptualized as monatomic molecules.
- As an illustration, oxygen (O2) is an example of a molecule with homonuclear properties, which means that all of its atoms are from a single chemical element. Conversely, it may possess heteronuclear attributes, representing a chemical compound composed of multiple elements, such as water (H2O). Atoms and complexes that are connected through non-covalent interactions, such as hydrogen bonds or ionic bonds, are typically not regarded as individual entities.
- A covalent bond is formed in the molecule H2, wherein two hydrogen atoms mutually share a pair of electrons.
- Ionic compounds that are bound by ionic bonds are referred to as ionic compounds. Within the realm of chemistry, an ionic compound can be defined as a chemical compound consisting of ions that are interconnected through the presence of electrostatic forces, commonly referred to as ionic bonding.
- The compound is electrically neutral, consisting of cations, which are positively charged ions, and anions, which are negatively charged ions. Ions can exist in different forms, including individual ions like sodium (Na+) and chloride (Cl–) in sodium chloride, as well as polyatomic ions like ammonium (NH4+) and carbonate (CO32-) in ammonium carbonate.
- The ions present in an ionic compound generally exhibit multiple nearest neighbors, indicating that they do not form discrete molecules. Instead, they form an interconnected three-dimensional lattice, typically adopting a crystalline arrangement.
- Acids are classified as ionic compounds that contain hydrogen ions (H+), while bases are classified as ionic compounds that contain basic ions such as oxide (O2) or hydroxide (OH).
- Ionic compounds that lack these ions are alternatively referred to as salts, which can be synthesized through acid-base reactions.
- Ionic compounds can be made in many ways, such as by evaporation, freezing, precipitation, solvent, electron transfer reactions, or solid-state reactions involving reactive metals and reactive non-metals, like halogen gases.
- Ionic compounds typically exhibit elevated boiling and melting points, as well as possessing characteristics of hardness and brittleness. In their solid state, these substances exhibit electrical insulating properties. However, upon undergoing liquefaction or dissolution, their conductivity greatly increases due to the mobilization of ions.
Example of an Ionic Compound
- An illustration of an ionic compound can be observed in the case of sodium chloride (NaCl), which is derived from the combination of sodium and chlorine.
- When chemical compounds are being formed, numerous elements exhibit a proclivity to acquire or relinquish electrons in order to achieve an electron configuration equivalent to that of the noble gas located nearest to them in the periodic table.
- Upon the interaction between sodium and chlorine, it is observed that each sodium atom willingly relinquishes an electron, thereby transforming into a Na+ ion. This ion retains its 11 protons within the nucleus yet possesses only 10 electrons, resembling the electronic configuration of neon. Conversely, each chlorine atom acquires an electron, leading to its conversion into a Cl– ion. This ion retains its 17 protons within the nucleus while accommodating 18 electrons, akin to the electronic configuration of argon.
- Solid sodium chloride consists of an equal number of positively charged cations (Na+) and negatively charged anions (Cl–), thereby ensuring the maintenance of electrical neutrality.
- Six chloride ions surround every sodium ion, and vice versa for each sodium ion. Because there are so many attractive interactions between Na+ and Cl–, the total electrostatic energy of attraction in NaCl is very high.
- An intermetallic, also known as an intermetallic compound, is a type of metallic alloy that forms a solid-state compound that exhibits distinct stoichiometry and an ordered crystal structure.
- Metallic bonds hold intermetallics together, making them a type of metallic compound. Intermetallics are also known as intermetallics.
- There exist specific complexes that are interconnected through the formation of coordinate covalent bonds. A coordination complex, typically of a metallic nature, is referred to as the coordination center.
- It consists of a closely arranged group of molecules or ions, known as complexing agents or ligands.
- Numerous compounds that incorporate metals, particularly those belonging to the transition metal category, are characterized as coordination complexes.
- A metal complex refers to a coordination complex wherein a metal atom serves as the central component.
Physical Property of Ionic Compound
- Ionic compounds exhibit a robust and crystalline nature, characterized by their high melting points and notable resistance to evaporation. The properties of an ionic solid arise from its internal structure, which is characterized by a three-dimensional lattice arrangement of alternating cations and anions, which are bound together by robust electrostatic interactions.
- Elevated temperatures are necessary to surmount the electrostatic forces of attraction existing between the cations and anions in ionic compounds. Hence, a substantial amount of energy is necessitated in order to induce the melting or boiling of ionic compounds.
- In the same way that ionic compounds tend to have higher melting and boiling points, their enthalpies of fusion and vaporization tend to be 10 to 100 times higher than those of most molecular compounds. The enthalpy of fusion refers to the amount of thermal energy needed to transform one mole of a solid substance into its liquid state while maintaining a constant pressure. The enthalpy of vaporization refers to the amount of heat energy that must be supplied to convert one mole of a liquid compound into its gaseous state while maintaining a constant pressure.
- Ionic crystals exhibit high hardness due to the robust electrostatic attraction between positively and negatively charged ions, rendering their separation arduous. Nevertheless, the application of pressure to an ionic crystal can compel ions of similar charge to approach each other in proximity. The phenomenon of electrostatic repulsion possesses sufficient magnitude to induce the fracture of a crystal lattice, thereby accounting for the inherent brittleness of ionic solids.
- When ionic compounds are dissolved in water, the dissociated ions become mobile. This makes it possible for electric charges to travel through the solution. Molten ionic compounds, commonly referred to as molten salts, exhibit the ability to conduct electric current.
Physical Properties of Molecular Compound
- The ions within an ionic compound exhibit a significant degree of mutual attraction, whereas covalent bonds give rise to molecules that can disassociate from one another upon the addition of a relatively smaller quantity of energy. Consequently, molecular compounds typically exhibit relatively low melting and boiling points.
- The enthalpy of fusion refers to the quantity of energy required, under constant pressure conditions, to convert one mole of a solid substance into its liquid state. The enthalpy of vaporization refers to the quantity of energy needed, under constant pressure conditions, to convert one mole of a liquid into its gaseous state. The phase transition of molecular compounds requires significantly less heat, typically ranging from 1% to 10% of the energy required for the phase transition of ionic compounds.
- This phenomenon can be primarily attributed to the inherent flexibility and ease of rupture of covalent bonds. The presence of covalent bonds in molecular compounds contributes to their characteristic states of matter, which can manifest as gases, liquids, or soft solids. Exceptions can arise in the case of molecular compounds, particularly when they adopt crystalline structures.
- Numerous combustible substances consist of hydrogen and carbon atoms, which have the capacity to engage in combustion, an exothermic reaction that liberates energy as the compound reacts with oxygen, resulting in the formation of carbon dioxide and water. Due to their similar electronegativities, carbon and hydrogen are frequently observed in conjunction with numerous molecular compounds.
- In order to facilitate the flow of electricity within an aqueous solution, the presence of ions is essential. Molecular compounds exhibit a tendency to dissolve into discrete molecular entities rather than undergo dissociation into ions. Consequently, their ability to conduct electricity when dissolved in water is generally limited.
- Numerous exceptions exist to this rule, analogous to the abundance of salts (ionic compounds) that exhibit limited solubility in aqueous solutions. Nevertheless, a significant number of covalent compounds exhibit polarity and possess the ability to readily dissolve in polar solvents, such as water. Sugar and ethanol are molecular compounds that exhibit high solubility in water. Oil and polymerized plastic are two instances of molecular compounds that exhibit limited solubility in water.
List of Chemical Compounds
|It is used as a baking ingredient
|Used to control algae and fungus
|Used and bleaching agent and disinfectant
|Used in laundry detergent
|Used in household cleaner as a disinfectant
|Used on a large scale for surface cleaning, bleaching, purification, odor removal, and water disinfection
|Used as a fungicide, and in medicine as a purgative
|Used in automotive brakes, and clutches
|Used in potassium soaps, detergents, and liquid fertilizers
|Calcium Magnesium Carbonate
|Used in the production of bricks, ceramics, and glass
|Used as a solvent for lacquer, resins, and floor polish
|Solid Carbon dioxide
|Used to preserve food
|Cream of tartar
|Used in a bakery to stabilize egg whites
|Used in fertilizer, explosives, and high-strength glasses
|Magnesium Sulfate Heptahydrate
|Used to relieve pain and inflammation
|Ferrous Sulfate Heptahydrate
|Used for sewage and water treatment and as a pigment and fertilizer
|Sodium Sulfate Decahydrate
|Used in medicine and as a dyeing agent
|Calcium Sulfate Dihydrate
|Used for drywall manufacturing
|Lead (II) Sulfide
|Used to make a green glaze that is applied in pottery
|Freon-12 / CFC-12
|Used as the refrigerant and aerosol spray propellant
|Used in the production of iron, steel, paper, and pulp
|Used in cement, paints, and building materials
|Used to produce pigment, preparation for heavy media separation, radiation shielding, etc
|Used in mortars, cement, and plasters
|Used in nuclear reactors, as a neutron moderator
|Used to produce pigment, preparation for heavy media separation, radiation sheilding, etc
|Sodium Thiosulfate Pentahydrate
|Used in films and photographic paper processing
|Used by dentist
|Used in fertilizers and explosives
|Milk of Magnesia
|Used as an antacid for upset stomach, heartburn
|Used in the manufacturing of alumina, soap and detergents, pulp and paper
|Used in fertilizer, rocket fuel, and sanitizing products
|Lead (II) Oxide
|Litharge (Red) and Massicot (Yellow)
|Used in lead glass, paints, enamels, and inks
|Ammonium Iron (II) Sulfate
|Used to increase the shelf life of iron and reduce oxidization
|Used in paint formation
|Calcium Sulfate Hemihydrate
|Plaster of Paris
|Used in the protective coating on walls and ceilings
|Potassium Aluminum Sulfate Dodecahydrate
|Used in water purification, leather tanning, and dyeing
|Used to make plastic and pesticides
|Oil of Vitriol
|Used to make fertilizers, pigments, dye, and explosive
|Used for symptomatic relief of acute pain in muscles, joints, and tendons
|Used for the production of batteries, photoflash bulb, and firework
|Used as a condiment and food preservative
|Used as a cleaning agent in several industrial processes
|Used in the manufacturing of fertilizers, pesticides, glass, fireworks, and explosives
|Used in the food industry for controlling crystallization, sweetness, and physical appearance
|Used as an oscillator in watches and radios
|Zinc Sulfate Heptahydrate
|Used for producing cosmetic and oral care products
|Used as a pigments for thousands of years
|Used in grenades, bombs, and other military weapons
|Used in the production of glass and soap
|Used for the manufacturing of inks, dyes, and perfumes
|Used in pencils and lubricants
|Used in medicine