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🧿 Radioactivity 🧿 ➖The process of emission of particles from nuclei because of the nuclear instability; is known as radioactivity. ➖The substance that releases such energy/rays is known as radioactive substance. ➖The invisible rays released from such radioactive substance are known as radioactive rays. ➖Likewise, radioactivity is a nuclear phenomenon that happens (naturally) because of the nuclear instability of atoms. ➖In 1896 Henri Becquerel first observed the phenomena of radioactivity, but the term ‘radioactivity’ was coined by Marie Curie. ➖Marie Curie discovered the radioactive elements namely Polonium and Radium in 1898. ➖For her discovery, Marie Curie won the Nobel Prize. ✅Radioactive Rays ➖After long years of experiment, Ernest Rutherford along with his colleague (Hans Geiger and his student Ernest Marsden), discovered alpha rays, beta rays, and gamma rays. ➖These rays emitted as the result of the disintegration of atoms. ✅Alpha (α) Particles ➖Alpha particles are usually composed of two protons and two neutrons, which are tightly bound together. ➖Alpha particles are being released during radioactive decay (or alpha decay) from the nucleus radio nuclides. ➖The alpha particles are identical to the nucleus of either normal helium atom or doubly ionized helium atom. ➖In comparison to other particles (i.e. Gamma and Beta), alpha particles are heavy and slow. Therefore, alpha particles have very small range in the air. ➖Because of slow speed, Alpha particles have very weak penetrating powers; these particles are even stopped by a thin paper sheet (see image given above). ➖Because of having the double positive charge, alpha particles are highly ionizing. ✅Beta (β) Particles ➖Beta particles are the fast moving electrons emitted by some radio nuclides during the radioactive decay (also known as beta decay). ➖Beta particles are of much lighter weight and carry a single negative charge. ➖Beta particles are rarely ionizing than the alpha particles. ➖Because of having lighter weight, beta particles can travel much farther than alpha particles; however, beta particles can be stopped by several sheet of papers or one sheet of aluminum. ➖Beta particles are negatively charged and get attracted towards positively charged particles. ✅Gamma (ү) Particles ➖Gamma particles are the bundle of high energy namely electromagnetic energy (photon) emitted by the radioactive elements during the radioactive decay. ➖Among all three particles (alpha, beta, and gamma), gamma particles are the most energetic photons. ➖Gamma particles, which are the form of electromagnetic radiation(EMR), originate from the nucleus. ➖The wavelengths of gamma are the shortest among all three. ➖Gamma particles have no charge and they are neutral; therefore, they are unaffected by magnetic and electric fields. ✅Uses of Radioactive Elements ➖Medical field (treatment of many diseases) ➖Industrial process ➖Energy production – Nuclear reactors ༆༆༆༆༆༆༆༆༆༆༆༆༆

📚 Some Basic Concepts of Chemistry 📚 Matter: Anything that exhibits inertia is called matter. The quantity of matter is its mass. Classification of Matter:- Based on chemical composition of various substances. 📍Elements: ➖It is the simplest form of the matter. ➖Smallest unit of an element is known as atom. ➖Total number of the known elements is 118 out of which 98 elements occur naturally and 20 are formed by artificial transmutation. ➖Examples: Na, K, Mg. Al, Si, P, C, F, Br etc. 📍Compound: ➖It is a non-elemental pure compound. ➖Formed by chemical combination of two or more atoms of different elements in a fixed ratio. ➖Examples: H2O, CO2, C6H12O6 etc. 📍Mixture: ➖Formed by physical combination of two or more pure substances in any ratio. ➖Chemical identity of the pure components remains maintained in mixtures. ➖Homogeneous mixtures are those whose composition for each part remains constant. ➖Example, Aqueous and gaseous solution. ➖Heterogeneous mixtures are those whose composition may vary for each and every part. ➖Example, Soil and concrete mixtures. 🧩Dalton’s Atomic Theory: ➖Every matter consists of indivisible atoms. ➖Atoms can neither be created nor destroyed. ➖Atoms of a given element are identical in properties ➖ Atoms of different elements differ in properties. ➖Atoms of different elements combine in a fixed ratio to form molecule of a compound. 🧩Precision and Accuracy: ➖Precision: Closeness of outcomes of different measurements taken for the same quantity. ➖Accuracy: Agreement of experimental value to the true value 🧩Laws of Chemical Combination: ➖Law of conservation of mass: “For any chemical change total mass of active reactants are always equal to the mass of the product formed” ➖Law of constant proportions: “A chemical compound always contains same elements in definite proportion by mass and it does not depend on the source of compound”. ➖Law of multiple proportions: “When two elements combine to form two or more than two different compounds then the different masses of one element B which combine with fixed mass of the other element bear a simple ratio to one another” ➖Law of reciprocal proportion: “ If two elements B and C react with the same mass of a third element (A), the ratio in which they do so will be the same or simple multiple if B and C reacts with each other”. ➖Gay Lussac’s law of combining volumes: “At given temperature and pressure the volumes of all gaseous reactants and products bear a simple whole number ratio to each other”. 🌀🌀🧪#Students_Notee

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🔰Proteins🔰 ✍️Introduction ➖Proteins, which are basically biomolecules, play wide range of functions in the body of a living organism. ➖Proteins are made up of tiny elements of different types of amino acids. ➖A sequence of amino acid residues in a protein is known particularly by the sequence of a gene; gene is encoded in the genetic code. ➖After formation, proteins exist for a fixed period of time and are then degraded and recycled. ➖The proteins get recycled by the cell's machinery by the process of protein turnover. ➖Most of the proteins contain linear polymers made up of series of up to 20 different L-α-amino acids. ➖The amino acids in a polypeptide chain are connected by peptide bonds. ➖The peptide bond, usually, has two resonance forms, which contribute some double-bond characters. ✍️Protein Structure ➖Most of the proteins illustrate unique 3-dimensional structures. ➖However, proteins have not a rigid structure, but rather, proteins may vary between several related structures especially when they perform their functions. ✍️Types of Protein ➖Enzymes − enzymes play important role especially during the breakdown of molecules. Enzymes are also required for the digestion and growth of the cell. ➖Structural Proteins − such type of proteins provide strength to cells, tissues, and organs. ➖Signaling Proteins − Such proteins facilitate cells to communicate with each other by providing signals. ➖Defensive Proteins − Such proteins help organisms to fight with infection and support damaged tissue in healing fast. ➖Hormone − Some hormones are proteins that help in metabolic activities. ለ Remedial program እና 9-12 ላሉ ተማሪዎች ቀዳም አስፈላጊ channel https://t.me/Ethio_Students_Note_and_pdf