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Positron Grade 10 SABIS The positron has the same mass as an electron but has a charge of 1+ is a subatomic particle that is similar to an electron in terms of mass but possesses a positive charge. It is often denoted as e+ and is considered the antiparticle of the electron. Despite having the same mass as an electron, the positron has an opposite charge of +1. Both the electron and the positron are classified as leptons, which are fundamental particles with no internal structure. They are part of the family of elementary particles in the Standard Model of particle physics. The mass of an electron and a positron is approximately 9.11 x 10^-31 kilograms. This mass is incredibly small, making electrons and positrons highly lightweight particles. The key difference between an electron and a positron lies in their electric charge. While an electron carries a negative charge of -1, the positron carries an equal but opposite positive charge of +1. The charges of the electron and the positron determine their behavior in electromagnetic interactions. Due to their opposite charges, electrons and positrons are attracted to each other and can undergo annihilation when they collide. When an electron and a positron collide, their charges cancel out, resulting in the production of energy in the form of gamma rays. This process is known as electron-positron annihilation. The existence of positrons was first theorized by Paul Dirac in 1928 and was later confirmed through experimental observations. The discovery of the positron contributed to the development of antimatter physics and had significant implications for our understanding of particle interactions. In practical applications, positrons have various uses, including in medical imaging techniques such as positron emission tomography (PET). In PET scans, positrons emitted by a radioactive substance interact with electrons in the body, leading to the detection of gamma rays and providing information about physiological processes. The study of particles like electrons and positrons is crucial in understanding the fundamental building blocks of matter and the intricate workings of the universe at the subatomic level. Advances in particle physics have led to numerous technological innovations and have broadened our knowledge of the fundamental laws governing the physical world. In summary, a positron shares the same mass as an electron but possesses a positive charge of 1+. Both particles are leptons, with the electron carrying a negative charge of -1. The existence of positrons was theorized and later confirmed through experimental observations. Understanding the properties and behavior of electrons and positrons contributes to our knowledge of particle physics and has practical applications in various fields, such as medical imaging.

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

The rate of the reaction can be defined as either: Grade 10 SABIS The quantity of products produced per unit time OR the quantity of reactants consumed per unit time.

Atomicity Definition General Atomicity is the term used to describe the number of atoms bonded together within a molecule. It represents the smallest unit of a compound that retains the chemical properties of that substance. Explanation with examples from here

Inverse Proportion A relationship between two variables where an increase in one variable leads to a decrease in the other variable, and vice versa.

Endothermic Reaction Grade 10 SABIS SABIS Is a reaction which absorbs heat from the surrounding. As heat is absorbed, the temperature of the surrounding decreases. Decomposition reactions like electrolysis of water, heating a substance, melting, vaporization and sublimation are examples of endothermic processes

Microscopic changes that take place when gases are heated very strongly Grade 10 SABIS When gases are heated very strongly, several microscopic changes occur at the molecular level. These changes involve the increased kinetic energy of the gas molecules and their interactions, leading to observable macroscopic effects such as expansion, increased collisions, and changes in the gas properties. As the gas is heated, the temperature of the system rises, and this increase in temperature corresponds to an increase in the average kinetic energy of the gas molecules. The molecules gain energy and move more rapidly, exhibiting increased translational, vibrational, and rotational motion. The increased kinetic energy causes the gas molecules to spread out and occupy a larger volume. This expansion occurs because the higher energy levels enable the molecules to overcome intermolecular forces and move farther apart. As a result, the gas expands to fill the available space. Furthermore, the increased kinetic energy leads to an increase in the frequency and intensity of molecular collisions. The molecules collide more frequently and with greater force, resulting in an overall increase in pressure. This increase in pressure can be observed macroscopically, such as in an inflated balloon. The increased molecular motion also affects the average speed of the gas molecules. According to the Maxwell-Boltzmann distribution, higher temperatures result in a greater distribution of molecular speeds, with more molecules possessing higher velocities. This increased molecular speed contributes to the overall energy and pressure of the gas. At very high temperatures, certain gases may undergo dissociation or ionization. Dissociation involves the breaking of molecular bonds, leading to the formation of individual atoms or smaller molecules. Ionization involves the removal or addition of electrons, resulting in the formation of ions. These processes contribute to the overall chemical behavior of the gas. In some cases, heating a gas very strongly can lead to the breakdown of ideal gas behavior. At high temperatures, the intermolecular forces between gas molecules can become more significant, deviating from the ideal gas assumptions of negligible intermolecular interactions. It's important to note that the microscopic changes when gases are heated very strongly are highly dependent on the specific gas and its molecular structure. Different gases may exhibit different behaviors and undergo unique molecular transformations at high temperatures. Understanding the microscopic changes that take place when gases are heated very strongly is crucial in various fields, including combustion, high-temperature processes, and astrophysics. It allows us to analyze energy transfers, thermodynamic properties, and the behavior of gases under extreme conditions. In summary, when gases are heated very strongly, microscopic changes occur at the molecular level, involving increased kinetic energy, expansion, increased molecular collisions, and potential dissociation or ionization. These changes influence the macroscopic properties and behavior of the gas, contributing to phenomena such as expansion, pressure increase, and alterations in chemical reactivity.

Proportional A relationship between two variables where an increase in one variable leads to a corresponding increase in the other variable, and vice versa.

Pressure The force applied per unit area.

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.

< Back Chapter 8: Molecules in the Gas Phase Understand the behavior of molecules in the gas phase and how to describe their properties using the gas laws. Chapter 8: Molecules in the Gas Phase - This chapter explores the behavior of gases and the properties of the gas phase. Students will learn about the gas laws, the ideal gas law, and the kinetic molecular theory. The chapter also covers the behavior of gases in real-world situations. Previous Next

< Back Chapter 5: Stoichiometry Discover the quantitative relationships between reactants and products in chemical reactions and learn how to apply stoichiometric calculations. Chapter 5: Stoichiometry - This chapter covers the calculations involved in chemical reactions. Students will learn how to balance chemical equations, calculate limiting reactants, and determine percent yield. The chapter also covers the mole concept and how to use it in stoichiometry problems. Previous Next