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Boyle's Law ​ ​ The principle that states the volume of a given amount of gas is inversely proportional to its pressure at a constant temperature.

Surrounding Grade 10 SABIS SABIS The environment around a system where a chemical reaction is taking place.

< Back Chemical bonding This is placeholder text. To change this content, double-click on the element and click Change Content. This is placeholder text. To change this content, double-click on the element and click Change Content. Want to view and manage all your collections? Click on the Content Manager button in the Add panel on the left. Here, you can make changes to your content, add new fields, create dynamic pages and more. You can create as many collections as you need. Your collection is already set up for you with fields and content. Add your own, or import content from a CSV file. Add fields for any type of content you want to display, such as rich text, images, videos and more. You can also collect and store information from your site visitors using input elements like custom forms and fields. Be sure to click Sync after making changes in a collection, so visitors can see your newest content on your live site. Preview your site to check that all your elements are displaying content from the right collection fields. Previous Next 🔬 Chapter 4: Chemical Bonding 🔬 Learning Outcomes 🎯: Describe different types of bonding using dot-and-cross diagrams, including ionic, covalent, and co-ordinate (dative covalent) bonding. Explain shapes and bond angles in molecules using electron-pair repulsion. Describe covalent bonding in terms of orbital overlap, sigma and pi bonds, and hybridization. Explain terms like bond energy, bond length, and bond polarity. Describe intermolecular forces based on permanent and induced dipoles, hydrogen bonding, and metallic bonding. Deduce the type of bonding present from given information. (Page 48) Van der Waals’ Forces 💨: Van der Waals’ forces are weak forces of attraction between atoms or molecules. They arise due to temporary dipoles set up by the movement of electron charge clouds. These forces increase with the increasing number of electrons and contact points between molecules. They play a significant role in the boiling points of noble gases and other substances. (Page 14) Bond Length and Bond Energy ⚛️: Double bonds are shorter and stronger than single bonds. Bond energy is the energy needed to break one mole of a given bond in a gaseous molecule. Bond strength influences the reactivity of a compound. (Page 6) Metallic Bonding 🧲: Metals have a giant metallic structure with positive ions surrounded by a sea of delocalized electrons. This structure explains why metals are good conductors of electricity and have high melting points. (Page 22) Hydrogen Bonding and Boiling Point 🌡️: Hydrogen bonding can cause compounds to have higher boiling points than expected. Water has a much higher boiling point and enthalpy change of vaporization due to extensive hydrogen bonding. (Page 17)

Essential Concepts of Atomic Structure: Grade 10 SABIS ​ Electrical Neutrality of Atoms : An atom is like a well-organized party where the number of positive guests (protons) equals the number of negative guests (electrons). This balance ensures that the overall mood (charge) of the party (atom) remains neutral. Formation of Positive Ions (Cations) : Imagine an atom as a generous friend who gives away one or more of its electrons. This act requires energy, like the effort it takes to give a gift. The result is a positive ion (or cation), where the number of protons exceeds the number of electrons. Formation of Negative Ions (Anions) : On the flip side, an atom can also be a gracious receiver, accepting one or more electrons. This usually releases energy, like the joy of receiving a gift. The result is a negative ion (or anion), where the number of electrons is greater than the number of protons. Stable Nucleus : A stable nucleus is like a timeless masterpiece. It can exist indefinitely, maintaining its composition and properties over time. Electron Position : Electrons are like free birds. They can be anywhere around the nucleus, and we can't predict their exact location at any given moment. However, they are more likely to be found closer to the nucleus, like birds prefer to stay near their nest. Atomic Number (Z) : The atomic number is like the ID card of an atom. It's the number of protons in the nucleus and equals the number of electrons in a neutral atom. It also determines the nuclear charge. Mass Number (A) : The mass number is like the total population of a city where protons and neutrons live. It's the total number of protons and neutrons (nucleons) in a nucleus and represents the mass of a given nucleus. Nuclear Representation : A nucleus of an atom is represented by ZX^A, where X is the element’s symbol, Z is the atomic number (number of protons), and A is the mass number (number of nucleons). Quarks : Protons and neutrons are like a bag of tiny particles called quarks. These are the fundamental constituents that make up protons and neutrons. Isotopes : Isotopes are like siblings. They belong to the same element family (same atomic number), but they have different weights (mass numbers). They have the same nuclear charge, the same number of electrons, and react chemically in the same way. For example, hydrogen has three isotopes: hydrogen, deuterium, and tritium. Similarly, oxygen has three isotopes: oxygen-16, oxygen-17, and oxygen-18. Despite their differences in mass, they are all still recognized as hydrogen or oxygen, respectively.

Conservation of molecules? Grade 10 SABIS SABIS Molecules are not necessarily conserved in chemical reactions.

Variation of PE as two H atoms approach each other Grade 10 SABIS ​ The variation of potential energy (PE) as two hydrogen atoms approach each other is influenced by the interplay between attractive and repulsive forces. As the atoms move closer together, the potential energy undergoes significant changes, which can be understood in terms of the interaction between their electron clouds and the electrostatic forces between the nuclei and electrons. When two hydrogen atoms are far apart, the electron clouds of each atom experience only weak attractive forces. At this point, the potential energy is relatively low since there is little interaction between the atoms. As the atoms start to approach each other, the electron clouds of the two atoms begin to overlap. The overlapping electron clouds create an attractive force between the atoms known as the London dispersion force. This force arises due to the temporary fluctuations in electron distribution and induces a slight attraction between the atoms. As the atoms get closer, the potential energy decreases further as the attractive forces become more significant. However, as the atoms continue to approach each other, the repulsive forces between their positively charged nuclei become more pronounced. These repulsive forces arise due to the electrostatic repulsion between the like charges of the protons in the nuclei. The potential energy starts to increase rapidly as the repulsion outweighs the attraction. At a certain point, known as the equilibrium bond length, the attractive and repulsive forces balance each other, resulting in the lowest potential energy between the two hydrogen atoms. This equilibrium bond length corresponds to the most stable configuration of the hydrogen molecule, where the potential energy is at its minimum. If the atoms are brought even closer together than the equilibrium bond length, the repulsive forces dominate, causing the potential energy to increase sharply. This indicates an unfavorable arrangement, and the atoms will experience a strong repulsion. The variation of potential energy as two hydrogen atoms approach each other can be visualized using a potential energy diagram. The diagram shows the change in potential energy as a function of the distance between the atoms, highlighting the regions of attraction, equilibrium, and repulsion. In summary, the variation of potential energy as two hydrogen atoms approach each other is determined by the balance between attractive and repulsive forces. Initially, there is a weak attraction due to electron cloud overlap, leading to a decrease in potential energy. However, as the atoms get closer, the repulsive forces between their nuclei become dominant, causing the potential energy to increase. At the equilibrium bond length, the potential energy reaches its minimum, indicating a stable configuration. Beyond this point, further approach results in a rapid increase in potential energy due to strong repulsion. Understanding the variation of potential energy provides insights into the stability and bonding behavior of hydrogen molecules.

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Conservation in Nuclear Reactions Grade 10 SABIS ​ Conservation laws play a fundamental role in nuclear reactions, ensuring that certain quantities are conserved before and after the reaction takes place. The conservation laws that apply to nuclear reactions include conservation of mass-energy, conservation of charge, conservation of momentum, and conservation of nucleon number. The conservation of mass-energy, as described by Einstein's equation E=mc², states that the total mass-energy before and after a nuclear reaction remains constant. Although mass may appear to change during a reaction, the sum of mass and energy remains conserved. This conservation law highlights the conversion of mass into energy or vice versa in nuclear processes. Conservation of charge states that the total electric charge before and after a nuclear reaction remains the same. The charges of the subatomic particles involved, such as protons and electrons, are conserved throughout the reaction. This conservation law ensures that the overall charge of the system remains balanced. Conservation of momentum in nuclear reactions states that the total momentum before and after the reaction remains constant. Momentum, which depends on the mass and velocity of particles, is conserved in both the linear and angular forms. This conservation law ensures that the total momentum of the interacting particles remains balanced. The conservation of nucleon number, also known as conservation of baryon number, states that the total number of nucleons (protons and neutrons) before and after a nuclear reaction remains constant. In reactions involving the nucleus, the total number of protons and neutrons is conserved. This conservation law emphasizes the stability of the nuclear composition. These conservation laws provide essential constraints on nuclear reactions, guiding our understanding of the behavior and outcomes of atomic nuclei. They help predict the products and quantities involved in nuclear processes and contribute to the overall understanding of nuclear physics. An example of conservation in nuclear reactions is the decay of a radioactive isotope. During radioactive decay, the conservation laws ensure that the total mass-energy, charge, momentum, and nucleon number remain constant, even as the unstable nucleus undergoes transformations. In nuclear fission reactions, where a heavy nucleus splits into smaller fragments, the conservation laws dictate that the total mass-energy, charge, momentum, and nucleon number of the reactants equal the total of the products. Similarly, in nuclear fusion reactions, where lighter nuclei combine to form a heavier nucleus, the conservation laws ensure that the quantities involved, such as mass-energy, charge, momentum, and nucleon number, are preserved. In summary, conservation laws play a crucial role in nuclear reactions, ensuring the preservation of certain quantities. Conservation of mass-energy, charge, momentum, and nucleon number provide constraints on the behavior and outcomes of nuclear processes. Understanding these conservation laws helps predict the behavior of atomic nuclei, analyze radioactive decay, and comprehend the transformations occurring in nuclear fission and fusion reactions.

5 use bond energies (ΔH positive, i.e. bond breaking) to calculate enthalpy change of reaction, ΔHr A Level Chemistry CIE Bond energies play a crucial role in calculating the enthalpy change of a chemical reaction (ΔHr). Bond energies represent the amount of energy required to break a particular bond within a molecule. By utilizing bond energies, we can estimate the overall energy change associated with the breaking and formation of bonds during a reaction. To calculate the enthalpy change of a reaction (ΔHr) using bond energies, we follow a simple approach. First, we identify the specific bonds that are broken and formed in the reaction. Then, we determine the bond energies for these bonds from reliable sources such as databases or experimental data. The bond energies typically have positive values, indicating that energy is required to break the bonds (ΔH positive, i.e., bond breaking). These bond energies are expressed in units of energy per mole (kJ/mol) and represent the average energy needed to break the bond in a large number of molecules. Next, we sum up the bond energies for the bonds broken in the reactants. This represents the energy required to break these bonds. We subtract the sum of the bond energies for the bonds formed in the products. This represents the energy released during the formation of new bonds. The enthalpy change of the reaction (ΔHr) can then be calculated as the difference between the total energy required to break the bonds and the total energy released during the formation of new bonds. The ΔHr value obtained from bond energies is an estimation of the enthalpy change, assuming the reaction occurs under standard conditions. It's important to note that bond energies are approximate values and can vary depending on the specific molecular environment and conditions. They provide a useful estimate for calculating enthalpy changes, but actual experimental values may differ due to factors such as bond strength variations and different reaction conditions. For example, in the combustion of methane (CH4) to form carbon dioxide (CO2) and water (H2O), we can use bond energies to estimate the enthalpy change. The C-H bonds in methane are broken, requiring energy input. At the same time, new bonds (C-O and O-H) are formed in the products, releasing energy. By summing up the bond energies for the broken and formed bonds, we can calculate an approximate enthalpy change for the reaction. Using bond energies to calculate the enthalpy change of a reaction provides a valuable tool for estimating energy changes in chemical processes. It allows us to gain insights into the energetics of reactions, compare the relative stabilities of different compounds, and predict the feasibility of chemical transformations. In summary, bond energies can be used to estimate the enthalpy change of a reaction (ΔHr) by summing up the energy required to break the bonds in the reactants and subtracting the energy released during the formation of new bonds in the products. Although bond energies provide approximate values, they serve as a useful tool for understanding the energy transformations involved in chemical reactions and making predictions about their enthalpy changes.

Atoms Grade 10 SABIS SABIS The smallest unit of an element that retains the chemical properties of that element.

Know the Potential Energy diagram for an Exothermic and Endothermic reactions Grade 10 SABIS ​ To understand how to determine the potential energy diagram for exothermic and endothermic reactions, let's first discuss what a potential energy diagram represents. A potential energy diagram is a graphical representation that shows the changes in potential energy of a chemical system as a reaction progresses. The vertical axis of the diagram represents the potential energy, while the horizontal axis represents the progress of the reaction from the initial state to the final state. Now, let's focus on exothermic reactions. An exothermic reaction is one that releases energy to the surroundings, usually in the form of heat. In an exothermic reaction, the products have lower potential energy than the reactants. This means that the potential energy decreases as the reaction proceeds. On a potential energy diagram for an exothermic reaction, the reactants are represented at a higher energy level compared to the products. The curve starts at a higher point (representing the energy of the reactants) and gradually decreases (representing the decrease in potential energy) as the reaction progresses towards the products. The difference in potential energy between the reactants and products is the amount of energy released to the surroundings. Now, let's move on to endothermic reactions. An endothermic reaction is one that absorbs energy from the surroundings. In an endothermic reaction, the products have higher potential energy than the reactants. This means that the potential energy increases as the reaction proceeds. On a potential energy diagram for an endothermic reaction, the reactants are represented at a lower energy level compared to the products. The curve starts at a lower point (representing the energy of the reactants) and gradually increases (representing the increase in potential energy) as the reaction progresses towards the products. The difference in potential energy between the reactants and products is the amount of energy absorbed from the surroundings. To determine the shape of the potential energy diagram, it is essential to consider the activation energy, which represents the energy barrier that must be overcome for the reaction to occur. The activation energy is depicted as the peak on the potential energy diagram. For an exothermic reaction, the activation energy is usually lower than the potential energy of the reactants, indicating that the reaction can readily occur. The potential energy decreases from the reactants to the products, with the activation energy acting as the barrier that needs to be overcome. In contrast, for an endothermic reaction, the activation energy is typically higher than the potential energy of the reactants. This indicates that more energy is required for the reaction to proceed. The potential energy increases from the reactants to the products, with the activation energy representing the energy threshold that must be surpassed. In summary, the potential energy diagram for exothermic reactions shows a gradual decrease in potential energy from the reactants to the products, while the diagram for endothermic reactions shows a gradual increase in potential energy. The activation energy represents the energy barrier that must be overcome. Understanding these diagrams helps visualize the energy changes and barriers involved in the progress of chemical reactions.