Molecular Compounds and Conductivity PDF

Created by Turbolearn AI Molecular Compounds and Conductivity Molecular compounds are typically unable to conduct current. This is because they do not contain metals, and current is defined as the physical movement of electrons through a substance. In molecular compounds, electrons are not shared,...

Created by Turbolearn AI Molecular Compounds and Conductivity Molecular compounds are typically unable to conduct current. This is because they do not contain metals, and current is defined as the physical movement of electrons through a substance. In molecular compounds, electrons are not shared, making it less likely for electrons to flow through the substance. Ionic Compounds and Conductivity In contrast, ionic compounds tend to be conductors, meaning they allow the conduction of electrons. This is because ionic compounds are made up of ions that are in close proximity to each other, allowing electrons to flow through the substance. Covalent Bonding Covalent bonding occurs when atoms share electrons to achieve a stable electron configuration. This is often seen in nonmetals and metalloids in groups 4A, 5A, 6A, and 7A of the periodic table. Characteristics of Covalent Bonds The following are characteristics of covalent bonds: Atoms share electrons to achieve a stable electron configuration Typically found in nonmetals and metalloids in groups 4A, 5A, 6A, and 7A of the periodic table Result in the formation of molecules Example: Hydrogen Molecule The hydrogen molecule H2 is an example of a covalent bond. Two hydrogen atoms share their electrons to form a stable molecule. Example: Ozone O3 Page 1  Created by Turbolearn AI Ozone is another example of a covalent bond. It is made up of three oxygen atoms that share their electrons to form a stable molecule. Ozone has several applications, including: Sanitizing air in hospitals and other public spaces Removing odors and pollutants from the air Used in water treatment plants to kill bacteria and other microorganisms Single Covalent Bonds A single covalent bond is a type of covalent bond where two atoms share one pair of electrons. A single covalent bond is defined as a bond where two atoms share one pair of electrons, resulting in a stable molecule. Characteristics of Single Covalent Bonds The following are characteristics of single covalent bonds: Two atoms share one pair of electrons Result in a stable molecule Typically represented by a straight line in Lewis dot structures Example: Fluorine Molecule The fluorine molecule F 2 is an example of a single covalent bond. Two fluorine atoms share their electrons to form a stable molecule. Unshared Pairs An unshared pair is a pair of electrons that are not shared between atoms. An unshared pair is defined as a pair of electrons that are not shared between atoms, and are typically found in the outer energy level of an atom. Characteristics of Unshared Pairs Page 2  Created by Turbolearn AI The following are characteristics of unshared pairs: Pair of electrons that are not shared between atoms Typically found in the outer energy level of an atom Do not participate in bonding Water Molecule The water molecule H2O is an example of a covalent bond. Oxygen has six available electrons, and needs two more to be happy. Hydrogen atoms plug into the available spaces, resulting in a bent shape. The following table summarizes the characteristics of the water molecule: Atom Number of Electrons Number of Electrons Needed Oxygen 6 2 Hydrogen 1 1 This bent shape is the reason why oceans and lakes can freeze without killing marine life. The bent shape of the water molecule allows it to form a crystalline structure that is less dense than liquid water, resulting in the formation of ice that floats on top of the liquid water.## Properties of Water Water is a unique substance that expands when it freezes, making it less dense than its liquid form. This property allows ice to float on top of liquid water. The reason for this expansion is due to the arrangement of water molecules, which have electronegative and electropositive regions. The electronegative region of a water molecule is the area where the oxygen atom is located, while the electropositive region is where the hydrogen atoms are located. As water molecules come together to form ice crystals, they arrange themselves in a way that maximizes the distance between the electropositive regions, resulting in a less dense structure. Methane Methane is a molecule composed of one carbon atom and four hydrogen atoms. The carbon atom has four valence electrons, which are evenly spaced and repel each other, resulting in a tetrahedral shape. Page 3  Created by Turbolearn AI Atom Valence Electrons Carbon 4 Hydrogen 1 The carbon atom in methane achieves a noble gas configuration by redistributing its electrons to form four covalent bonds with the hydrogen atoms. Hydrochloric Acid Hydrochloric acid is prepared by dissolving hydrogen chloride gas in water. The hydrogen chloride molecule is a diatomic molecule with a single covalent bond. Hydrogen chloride is a toxic gas that can cause damage to the lungs and other tissues. When hydrogen chloride is inhaled, it reacts with the water in the lungs to form hydrochloric acid, which can cause severe burns and damage to the tissues. Double and Triple Bonds A double bond is a type of covalent bond where two pairs of electrons are shared between two atoms. A triple bond is a type of covalent bond where three pairs of electrons are shared between two atoms. Type of Bond Number of Electron Pairs Shared Single Bond 1 Double Bond 2 Triple Bond 3 The energy required to break a double or triple bond is greater than the energy required to break a single bond. Carbon Dioxide Carbon dioxide is a molecule composed of one carbon atom and two oxygen atoms. The carbon atom is bonded to the two oxygen atoms through double bonds. Page 4  Created by Turbolearn AI Atom Valence Electrons Carbon 4 Oxygen 6 The carbon dioxide molecule has a linear shape, with the two oxygen atoms bonded to the carbon atom through double bonds. Nitrogen Nitrogen is a diatomic molecule with a triple bond between the two nitrogen atoms. The triple bond makes it difficult to break the nitrogen molecule apart. Nitrogen is an essential element for life, and it is a major component of amino acids and nucleotides. The triple bond in nitrogen makes it a stable molecule, but it also makes it difficult to react with other molecules. Oxygen Oxygen is a diatomic molecule with a double bond between the two oxygen atoms. However, the oxygen molecule does not obey the octet rule, and it has two unpaired electrons. The octet rule states that atoms tend to gain, lose, or share electrons to achieve a full outer energy level, which typically consists of eight electrons. The oxygen molecule has a paramagnetic property due to the presence of unpaired electrons.## Carbon Monoxide Poisoning Carbon monoxide is a colorless, tasteless, and flammable gas that can be deadly in large quantities. It is produced by the incomplete combustion of fossil fuels, such as propane, natural gas, and fuel oil. Carbon monoxide poisoning occurs when this gas displaces oxygen in the lungs, leading to a range of symptoms, including: Lethargy Nausea Headache Fever Sleepiness Page 5  Created by Turbolearn AI Carbon monoxide poisoning is often mistaken for the flu, as the symptoms are similar. However, it is essential to recognize the difference, as carbon monoxide poisoning can be fatal if left untreated. Coordinate Covalent Bonding Coordinate covalent bonding is a type of bonding where one atom shares its electrons with another atom to achieve a stable configuration. This type of bonding is different from other covalent bonds, as it involves the sharing of electrons between atoms with different electronegativities. Atom Electrons Needed to Achieve Stability Carbon 4 Oxygen 2 In the case of carbon monoxide, the carbon atom shares its electrons with the oxygen atom to achieve a stable configuration. The oxygen atom donates 2 electrons to the carbon atom, resulting in a triple bond between the two atoms. Polyatomic Ions A polyatomic ion is a group of atoms that are bonded together and have a positive or negative charge. These ions can be found in a variety of compounds and are essential to understanding chemistry. Polyatomic Ion Formula Charge Ammonium ion NH4+ +1 Hydronium ion H3O+ +1 A polyatomic ion is a tightly bound group of atoms that have a positive or negative charge and behave as a unit. The ammonium ion forms when a positively charged hydrogen ion attaches to the unshared electron pair of an ammonia molecule. This results in a positive charge on the entire molecule. Drawing Electron Dot Structures Page 6  Created by Turbolearn AI Drawing electron dot structures is an essential skill in chemistry. It involves representing the electrons in an atom or molecule using dots. Molecule Electron Dot Structure Water H2O Ammonia NH3 When drawing electron dot structures for polyatomic ions, it is essential to remember that the entire molecule has a charge, not just a single atom. Exceptions to the Octet Rule The octet rule states that atoms tend to gain or lose electrons to achieve a full outer energy level, which typically consists of 8 electrons. However, there are some exceptions to this rule, including: Molecules with an odd number of valence electrons, such as nitrogen dioxide NO2 Molecules with an even number of valence electrons, but with atoms that do not follow the octet rule, such as boron and sulfur hexafluoride SF 6 These exceptions are essential to understanding the behavior of atoms and molecules in chemistry.## Bond Dissociation Energy The strength of a covalent bond is related to its bond dissociation energy, which is the energy required to break the bond between two atoms. Bond dissociation energy is the energy required to break a bond between two atoms, typically measured in kilojoules per mole. A large bond dissociation energy corresponds to a strong covalent bond. For example, the bond dissociation energy of a carbon-carbon single bond is approximately 347 kilojoules per mole, indicating a strong bond. Examples of Bond Dissociation Energy Molecule Bond Dissociation Energy kJ/mol Hydrogen Molecule H2 435 Carbon-Carbon Single Bond 347 Page 7  Created by Turbolearn AI Resonance Resonance occurs when a molecule has multiple possible electron dot structures that are equivalent in energy. Resonance is a phenomenon where a molecule has multiple possible electron dot structures that are equivalent in energy, and the actual structure is a hybrid of these resonance structures. In the case of the ozone molecule O3, there are two possible electron dot structures that are mirror images of each other. These structures are connected by a double- headed arrow to indicate resonance. Characteristics of Resonance The resonance structures are identical in every way except for the orientation of the electron pairs. The bond lengths in resonance structures are often equal, despite initial predictions that they would be unequal. Resonance is used to model the bonding in molecules that cannot be adequately described by a single structural formula. Molecular Compounds Molecular compounds are formed when two or more atoms or molecules bond together. It is essential to distinguish between atoms and molecules to understand the composition of molecular compounds. Page 8