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Cooling Stage ​ ​ The portion of the curve where the substance is being cooled, resulting in a decrease in temperature and average kinetic energy of the particles.

Know that in for endothermic reactions H products > H reactants, ∆ H> 0 and reaction absorbs energy Grade 10 SABIS ​ In chemical reactions, an endothermic reaction is one that absorbs energy from the surroundings. It is characterized by the fact that the enthalpy (H) of the products is greater than the enthalpy of the reactants. This change in enthalpy (∆H) is positive, indicating that energy is absorbed during the reaction. To understand endothermic reactions, let's consider an everyday example: the process of cooking pasta. When you boil water and add pasta to it, the reaction between the pasta and the hot water is endothermic. The energy from the heat source is absorbed by the pasta, causing it to cook and increase in temperature. In an endothermic reaction, the potential energy of the products is higher than that of the reactants. This means that the reactants have a lower energy level compared to the products. As the reaction progresses, energy is absorbed from the surroundings, leading to an increase in potential energy. 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 proceeds towards the products. The difference in potential energy between the reactants and products is the amount of energy absorbed from the surroundings. The positive value of ∆H indicates that the reaction absorbs energy. This energy can be in the form of heat, light, or any other form of energy. In the case of the cooking pasta example, the absorbed energy is in the form of heat from the boiling water. Endothermic reactions are essential in various processes. For instance, in photosynthesis, plants absorb energy from sunlight to convert carbon dioxide and water into glucose and oxygen. This process requires energy input to drive the reaction. Another example is the process of evaporation. When a liquid evaporates, it absorbs energy from the surroundings, causing a cooling effect. This is because the liquid particles need to gain energy to break the intermolecular forces and transform into a gas state. Endothermic reactions are also prevalent in chemical reactions used for cooling, such as instant cold packs or ice packs. These packs contain chemicals that undergo an endothermic reaction when activated, absorbing heat from the surroundings and providing a cooling sensation. In summary, endothermic reactions are characterized by the absorption of energy from the surroundings. The enthalpy of the products is greater than that of the reactants, resulting in a positive change in enthalpy (∆H). On a potential energy diagram, the potential energy increases from the reactants to the products, indicating the energy absorbed during the reaction. Understanding endothermic reactions helps us comprehend processes that require energy input and have a cooling effect, such as cooking, photosynthesis, evaporation, and cooling packs.

A stable compound has a low level of potential energy. Grade 10 SABIS ​

< Back Atomic Structure Lesson 1 ⚛️ Lesson 1 ⚛️ Get Ready by joining Lesson 1 , it is easy but you need to know it .Explore the structure of an atom and its subatomic particles in this visually enhanced quiz. Learn about atomic and ionic radii, understand the role of protons, neutrons, and electrons, and discover how to determine the number of neutrons in an atom. Embark on a journey through the microcosm of atoms and ions and unlock the secrets of the periodic table! Previous Next ⚛️ 1.1.1Structure of an Atom ⚛️ Welcome ! Today we are diving into the heart of matter to understand the structure of an atom. Let's get started! 💠 Atomic Structure 💠 Matter, as we know it, is composed of atoms, the smallest particles of an element capable of engaging in chemical reactions. The core of an atom is a very small, dense nucleus surrounded by a large area of mostly empty space. 1️⃣ Nucleus: It contains protons and neutrons, giving the nucleus an overall positive charge. 2️⃣ Protons: These particles carry a positive charge. 3️⃣ Neutrons: These particles are neutral, with no charge. 4️⃣ Electrons: These are negatively charged particles that reside in orbitals around the nucleus. Remember, the diagram of an atom is not to scale; the nucleus is much smaller compared to the overall size of the atom. 🎲 Subatomic Particles 🎲 Atoms are made up of protons, neutrons, and electrons, referred to as subatomic particles. Their masses and charges are usually relative and not actual charges and masses. 1️⃣ Protons and Neutrons: They both have a similar mass and are assigned a relative mass of 1. 2️⃣ Electrons: They are 1836 times smaller than a proton or a neutron, and their mass is usually considered negligible. Here are their relative masses and charges: Proton: Relative mass = 1, Charge = +1 Neutron: Relative mass = 1, Charge = 0 Electron: Relative mass ≈ 0 (negligible), Charge = -1 Q1: What are the relative masses and charges of protons, neutrons, and electrons? 🐘🪶 Picture this: a colossal elephant 🐘 named Proton, a mighty rhino 🦏 named Neutron, and a tiny, agile mouse 🐁 called Electron. These three are the heart and soul of our extraordinary, molecular circus, much like protons, neutrons, and electrons being the star ⭐ performers in the grand show of an atom. Just like in a regular circus, it's important to know our performers' talents and traits. But we can't use the conventional tools 🔧🔨! Imagine trying to weigh these performers on a feather 🪶 scale. It's just not accurate enough! It's the same with subatomic particles: we can't measure their masses and charges using everyday units like grams or coulombs. So, to bypass this problem, we dive into the world of 'relatives' 🎭. Imagine if we said, "Compared to the elephant 🐘, the rhino 🦏 weighs the same, but the mouse 🐁 is much, much lighter." We're not giving their weights in pounds or kilograms; instead, we're comparing their weights relative to each other. In the same manner, the mass of a proton is taken as a standard 🏆 (like our elephant 🐘), and it's given a 'relative mass' of 1️⃣. The neutron (our rhino 🦏) also weighs as much as the proton, so it too has a relative mass of 1️⃣. But our tiny mouse 🐁, the electron, is much lighter, with a relative mass of only 1/1836 ❗ And just like our performers have different weights, they also have different charges. The proton (our jolly, positive 🟢 elephant) has a relative charge of +1️⃣, the electron (the negatively charged 🔴 mouse) has -1️⃣, and the neutron (the neutral 🔘 rhino) is a 0️⃣. So remember, these 'relative' masses and charges are like comparisons, not actual masses or charges. It's like comparing our elephant, rhino, and mouse in our molecular circus! 🎪🌈 🔑 Atomic Key Terms 🔑 There are a few terms that you need to know to understand the structure of an atom. 1️⃣ Atomic Number (Z): It is the number of protons in the nucleus of an atom. In a neutral atom, the atomic number is also equal to the number of electrons. 2️⃣ Mass Number (A): It is the total number of protons and neutrons (nucleons) in the nucleus of an atom. The number of neutrons in an atom can be calculated by subtracting the atomic number from the mass number. Number of Neutrons = Mass Number - Atomic Number Q2: If an atom has a mass number of 11 and an atomic number of 5, how many neutrons does it have? 📚 Exam Tip 📚 In the Periodic Table, each element is represented with its mass number and atomic number. This notation helps us understand the structure of the atom for that particular element. Stay tuned for more lessons where we delve deeper into the Periodic Table and explore the properties and behaviors of atoms! 💥🔬📚 Quiz Level 1: Beginner Level 🌱 What is the smallest part of an element that can participate in chemical reactions? 🤔 Where are protons and neutrons found in an atom? 📍 What is the charge of an electron? ⚡ What do we call the particles that an atom is made up of? 🎭 What is the relative mass of an electron compared to protons and neutrons? ⚖️ Answers: An atom. In the nucleus of an atom. Negative. Subatomic particles. The mass of an electron is often considered negligible, being around 1/1836 times smaller than that of protons and neutrons. Level 2: Novice Explorer 🧭 Quiz What are the charges of protons, neutrons, and electrons, respectively? 🌈 What does the atomic number of an atom tell us? 🔢 What is the term for protons and neutrons together? 🤝 How can we calculate the number of neutrons in an atom? 🧮 What is the space called that electrons move around in, outside the nucleus? 🌌 Answers: Protons have a positive charge, neutrons have no charge (neutral), and electrons have a negative charge. The atomic number tells us the number of protons in the nucleus of an atom. Protons and neutrons together are called nucleons. The number of neutrons = mass number - atomic number. This space is called the electron cloud or orbitals. ⚛️ Level 3 Questions: Structure of an Atom ⚛️ : Practicing More 💪 🔬💫 Level 3: Structure of an Atom 💫🔬 Describe the structure of an atom, giving details of the subatomic particles present. [6] Explain the terms atomic number and nucleon number. [2] 💡 Atomic Number (Z) - The atomic number represents the number of protons in an atom's nucleus, determining its unique identity. 🎯 💡 Nucleon Number (A) - The nucleon number, also known as the mass number, signifies the total number of protons and neutrons in the nucleus. 🔢 Copy and complete the table: 📋 [2] Explain why atoms are neutral. [1] An oxygen atom has 8 protons in its nucleus. Explain why it cannot have 9 protons. [1] When calculating the relative mass of an atom, the electrons are not used in the calculation. Explain why not. [1] 🌟💡 Level 3 Answers: Structure of an Atom 💡🌟 The structure of an atom revolves around its nucleus, containing protons and neutrons, while electrons occupy energy levels or shells surrounding the nucleus. Protons bear a positive charge, neutrons are neutral, and electrons carry a negative charge. ⚛️ Atomic Number (Z) signifies the count of protons, determining the element's identity. It corresponds to the number of electrons in a neutral atom. 💫 Nucleon Number (A) accounts for the total protons and neutrons present in the nucleus, representing the atom's mass. 📊 Atoms are neutral since they possess an equal number of positively charged protons and negatively charged electrons. This balance of charges yields an overall neutral charge. ⚖️ An oxygen atom with 8 protons cannot have 9 protons since the number of protons defines its identity as oxygen. Altering the proton count would result in a different element. 🚫 When calculating the relative mass of an atom, electrons are not considered due to their significantly smaller mass compared to protons and neutrons. An electron's mass is approximately 1/1836 amu, whereas protons and neutrons have a mass close to 1 amu. Consequently, electrons have a negligible impact on the overall mass calculation. ⚖️❌ Stay tuned for more exciting lessons on the atomic world and its mesmerizing phenomena! 🌌🔬✨ Quiz Level 4: Pro Player 🏅 If an atom's mass number is 12 and its atomic number is 6, how many neutrons does it have? 🧠 Why is an atom mainly empty space? 🌌 Can the number of protons in an atom change? Why or why not? 🔄 What is the role of electrons in chemical reactions? ⚗️ If an atom gains an electron, does it become positively or negatively charged? Why? 🎭 Answers: The atom has 6 neutrons (mass number - atomic number = 12 - 6). An atom is mainly empty space because the electrons orbit the nucleus in this space, and electrons are much smaller than the nucleus. The number of protons in an atom cannot change, as changing the number of protons would change the identity of the element (its atomic number). Electrons participate in chemical bonds, either being transferred (ionic bonds) or shared (covalent bonds) between atoms. If an atom gains an electron, it becomes negatively charged because electrons carry a negative charge. Quiz Level 5: Expert Challenger 🏆 What determines the identity of an element? 🔎 How does the arrangement of electrons impact the chemical properties of an atom? 🌈 How does the atomic number affect the position of an element in the periodic table? 📚 What happens to the charge of an atom if it loses an electron? Why? 🎭 If an atom's mass number is 14 and it has 7 neutrons, what is its atomic number? 🧮 Answers: The number of protons (atomic number) in an atom determines the identity of an element. The arrangement of electrons, especially those in the outermost shell (valence electrons), impacts the chemical properties of an atom as they are involved in bonding. The atomic number determines the position of an element in the periodic table; elements are arranged in order of increasing atomic number. If an atom loses an electron, it becomes positively charged because it loses a negatively charged particle. The atom has an atomic number of 7 (mass number - number of neutrons = 14 - 7).

< Back Prerequisites for Chapter 5: States of Matter ​ Prerequisite Previous Next 🌟📘 Prerequisites for Chapter 5: States of Matter 📘🌟 Before diving into Chapter 5, which deals with states of matter, students must have a solid understanding of the following concepts: 🔬 1. Basic Particle Theory 🧪 Understand that matter is made up of particles and the differences in particle arrangement in solids, liquids, and gases. 🔬 2. Temperature and Heat 🌡️ Understand the concept of temperature as a measure of the average kinetic energy of particles. Know the difference between heat and temperature. 🔬 3. Pressure 📐 Understand the concept of pressure and its relationship with force and area. Know how pressure is related to the motion of particles in gases. 🔬 4. Intermolecular Forces 💪 Have a basic understanding of the forces between molecules, such as van der Waals forces and hydrogen bonding. 🔬 5. Phase Changes 🔄 Understand the processes of melting, freezing, evaporation, condensation, sublimation, and deposition. 🌟 20 Multiple Choice Questions to Check Mastery of Prerequisites 🌟 Which state of matter has a definite shape and volume? a) Solid b) Liquid What happens to the particles of a substance during melting? a) They gain kinetic energy and move apart. b) They lose kinetic energy and move closer. c) They gain potential energy and move closer. d) They lose potential energy and move apart. What is the pressure exerted by a gas due to? a) Collisions of gas particles with each other. b) Collisions of gas particles with the walls of the container. c) The weight of the gas particles. d) The volume of the gas particles. Which of the following is NOT a type of intermolecular force? a) Ionic bond b) Hydrogen bond c) Dipole-dipole interaction d) London dispersion forces What is the process of a liquid turning into a gas called? a) Melting b) Freezing c) Evaporation d) Condensation Which state of matter has particles that are far apart and move freely? a) Solid b) Liquid c) Gas d) Plasma What is the SI unit of pressure? a) Pascal b) Newton c) Joule d) Watt What is the boiling point of water at standard atmospheric pressure? a) 0°C b) 25°C c) 100°C d) 212°C What happens to the pressure of a gas if the volume is decreased while the temperature is constant? a) Pressure increases. b) Pressure decreases. c) Pressure remains the same. d) Pressure becomes zero. Which phase change involves a solid turning directly into a gas? a) Melting b) Sublimation c) Evaporation d) Deposition What is the process of a gas turning into a liquid called? a) Melting b) Freezing c) Evaporation d) Condensation Which of the following is an example of a substance that exhibits hydrogen bonding? a) H₂O b) O₂ c) N₂ d) He What happens to the kinetic energy of particles as the temperature increases? a) Kinetic energy increases. b) Kinetic energy decreases. c) Kinetic energy remains the same. d) Kinetic energy becomes zero. In which state of matter do particles vibrate around fixed positions? a) Solid b) Liquid c) Gas d) Plasma What is the process of a gas turning directly into a solid called? a) Melting b) Sublimation c) Evaporation d) Deposition Which of the following is a measure of the average kinetic energy of the particles in a substance? a) Heat b) Pressure c) Temperature d) Volume What type of intermolecular force is present between nonpolar molecules? a) Hydrogen bonding b) Dipole-dipole interaction c) Ionic bonding d) London dispersion forces Which of the following will increase the rate of evaporation of a liquid? a) Decreasing the surface area b) Decreasing the temperature c) Increasing the humidity d) Increasing the temperature What is the process of a liquid turning into a solid called? a) Melting b) Freezing c) Evaporation d) Condensation Which of the following best describes the particles in a solid? a) Tightly packed and vibrating in place b) Tightly packed and moving freely c) Far apart and moving freely d) Far apart and vibrating in place 🌟 Answers 🌟 a) Solid a) They gain kinetic energy and move apart. b) Collisions of gas particles with the walls of the container. a) Ionic bond c) Evaporation c) Gas a) Pascal c) 100°C a) Pressure increases. b) Sublimation d) Condensation a) H₂O a) Kinetic energy increases. a) Solid d) Deposition c) Temperature d) London dispersion forces d) Increasing the temperature b) Freezing a) Tightly packed and vibrating in place

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Condensation ​ ​ The process of a substance changing from a gaseous to a liquid state at a specific temperature.

Bond Energy Grade 10 SABIS ​ Bond energy refers to the amount of energy required to break a chemical bond between atoms or molecules. When atoms or molecules come together to form a bond, energy is released. Conversely, breaking a bond requires an input of energy.Imagine holding two magnets together. The energy you need to separate them represents bond energy. Similarly, when you pull apart two Lego blocks connected by studs, it requires energy to break the bond holding them.Forming a bond involves the attraction and sharing or transfer of electrons between atoms or molecules. This process releases energy. For example, when two puzzle pieces fit perfectly and snap together, the energy released represents bond formation .In a chemical reaction, the overall energy change is related to bond energy. When bonds are broken in reactant molecules, energy is absorbed. On the other hand, when new bonds are formed in the product molecules, energy is released. The difference between the energy absorbed and the energy released represents the bond energy change during the reaction.For instance, in a combustion reaction, such as the burning of gasoline, the energy released is due to the breaking of bonds in the reactant molecules (fuel and oxygen) and the formation of new bonds in the product molecules (carbon dioxide and water).Bond energy is an important concept in understanding the stability of molecules and the energy changes associated with chemical reactions. It helps explain why certain reactions release energy (exothermic) and others require energy input (endothermic). By studying bond energy, scientists can better understand the behavior of chemicals and design reactions for specific purposes.

Mass Grade 10 SABIS SABIS A measure of the amount of matter in an object, usually measured in grams or kilograms.

Coefficient Grade 10 SABIS SABIS The number preceding the chemical symbol and indicating the quantity of particles

Sublimation ​ ​ The process of a substance changing directly from a solid to a gaseous state at a specific temperature.

Effect of changing surface area on rate of reaction: Grade 10 SABIS ​ if one of the reactants is a solid, the more divided or broken it is, the larger is its surface area and the more particles will be in contact with the other reactant. This leads to particles colliding more frequently and so the rate increases.