Physical Science Notes 3rd Quarter 2024-2025 PDF

NOTES in PHYSICAL SCIENCE – 3rd Quarter (S.Y. 2024 – 2025) Stellar nucleosynthesis involves nuclear fusion and neutron capture. Elements heavier than iron-56 are not produced through nuclear fusion; instead, they are assembled through the capture of neutrons, thus creating a heavier isot...

NOTES in PHYSICAL SCIENCE – 3rd Quarter (S.Y. 2024 – 2025) Stellar nucleosynthesis involves nuclear fusion and neutron capture. Elements heavier than iron-56 are not produced through nuclear fusion; instead, they are assembled through the capture of neutrons, thus creating a heavier isotope of a particular element. We call this process as Neutron capture. Supernova nucleosynthesis is a process that occurs during the explosive death of massive stars. It is responsible for the creation of heavy elements beyond iron in the periodic table. Supernova nucleosynthesis is responsible for the formation of elements beyond iron in the periodic table. The intense conditions during a supernova explosion allow for the fusion of lighter elements into heavier ones, including elements like gold, silver, and uranium. CNO cycle stops once the star has used all the hydrogen in its core. In the laboratory, the synthesis of transuranic elements, particularly those beyond those found in nature, often involves the use of particle accelerators. In 1911, Ernest Rutherford’s Gold foil experiment realizes that positive charge was localized in the nucleus of an atom. He called it the Nuclear model. Proton and neutron are subatomic particles that are found inside the nucleus. Polar covalent bonding is involved when the bonding of electrons is shared unequally between two atoms. PCl5 is a covalent compound. To determine the polarity of a molecule through its molecular shape, we investigate the symmetricity. If the molecule is symmetrical, the molecule is NON-POLAR. If the molecule is asymmetrical, the molecule is POLAR. The presence of “lone pairs” will tell you that the shape of a molecule is asymmetrical. CS2 has a nonpolar covalent bonds. PCl5 is an example of a covalent compound. NH3 has a trigonal pyramidal shape. The polarity of materials/ molecules determines if they are soluble in water and not in other liquids. A salt solution is a good conductor of electricity. Sand and salt do not melt quickly when heated. Salt dissolves immediately in water. Hydrogen bonding is a strong type of dipole-dipole interaction that occurs when a hydrogen atom is bonded to a highly electronegative atom, such as oxygen, fluorine or nitrogen. Liquids can form spherical elastic film to minimize surface area. This is made possible because of H-Bonding. London-induced dipole exists between ions and a non-polar compound. The high boiling point of water is primarily due to hydrogen bonding between water molecules. Butter is a mixture of fats, and its solid-state at room temperature is due to the presence of strong intermolecular forces, such as van der Waals forces. When heated, the temperature increase provides enough energy to overcome these intermolecular forces, causing them to break. Concrete is used in construction because they are sturdy. Sports equipment should have strong IMFA’s because they need to be strong. Proteins play a key role in catalyzing biochemical reactions. Enzymes, which are specialized proteins, act as catalysts that facilitate and accelerate chemical reactions in living organisms. Carbohydrates are organic compounds made up of carbon, hydrogen, and oxygen Active sites are specific regions of a protein where catalytic activity occurs. By modifying the amino acid sequence (primary structure), the tertiary structure may be altered, leading to a misalignment or disruption of the active sites. This disturbance in the tertiary structure can result in the loss of catalytic activity, as the active sites are essential for facilitating biochemical reactions. Lipids function as long-term energy storage in the body. They insulate the body to protect us against heat loss. The structure of lipids, particularly in the cell membrane, plays a critical role in maintaining the fluidity and permeability of the membrane. Changes in lipid composition can impact these properties, affecting various cellular functions such as transport of molecules across the membrane and signaling processes. According to simple collision theory, an increase in the concentration of reactants leads to a higher number of collisions between particles.  An increase in temperature, according to simple collision theory, results in higher kinetic energy of particles. This higher energy leads to more frequent and energetic collisions between particles, increasing the chances of successful collisions and, consequently, increasing the rate of reaction. Absorption of heat, change of color, and liberation of heat shows evidence of a chemical reaction. While an increase in temperature generally leads to a faster rate of reaction according to simple collision theory, it is crucial to consider the specific reactants and their activation energy. The activation energy barrier must still be overcome for a reaction to occur. Some reactions may not be significantly affected by temperature if their activation energy is high. The primary role of a catalyst is to speed up a reaction by lowering the activation energy required for the reaction to occur. Importantly, a catalyst remains unchanged after the reaction and does not alter the total energy change or the concentrations of products. A catalyst is a substance that increases the rate of a chemical reaction by providing an alternative reaction pathway with lower activation energy. Importantly, a catalyst remains unchanged and is not consumed during the reaction. To investigate the effect of particle size on the rate of reaction, it is essential to isolate the variable of interest while keeping other factors constant. By keeping temperature and concentration constant and varying particle size, any observed changes in the rate of reaction can be attributed to the influence of particle size. In a reaction between 5 moles of nitrogen gas (N2) and 8 moles of hydrogen gas (H2) according to the balanced equation: N2(g)+3H2(g)→2NH3(g). Hydrogen gas (H2) will be the limiting reactant and 5 moles of ammonia will form. In a reaction involving 3 moles of hydrogen gas (H2) and 4 moles of oxygen gas (O2), with a balanced chemical equation of: 2H2(g)+O2(g)→2H2O(g), the limiting reactant will be the Hydrogen gas. If 8 moles of sulfur dioxide (SO2) react with 6 moles of oxygen (O2) in the reaction: 2SO2(g)+O2(g)→2SO3(g). Sulfur dioxide will be the limiting reactant and 8 moles of sulfur trioxide (SO3) will be formed. Fossil fuels, including coal, oil, and natural gas, are primarily associated with the combustion of organic matter. Geothermal energy involves harnessing heat from the Earth's interior, typically through the use of steam or hot water reservoirs beneath the Earth's surface. In contrast, biomass energy is derived from the combustion of organic matter, such as plants or animal waste. In a remote location with abundant sunlight and agricultural waste, a combination of biomass and solar energy would be suitable. Fossil fuels, when burned, release carbon dioxide and other pollutants, contributing to climate change and air pollution. In contrast, biomass combustion is considered carbon-neutral since the carbon released during combustion is part of the natural carbon cycle. Both geothermal and hydrothermal power involve harnessing the Earth's internal heat. Geothermal power typically extracts heat directly from the Earth's interior, while hydrothermal power often involves capturing steam generated by the interaction of water with hot rocks beneath the Earth's surface. Mineral deposits, often composed of minerals like calcium and magnesium, can be effectively removed by acids. Hydrochloric acid (HCl) is a strong acid commonly used in cleaning products designed for descaling or removing mineral deposits. Surfactants contribute to the formation of foam, aiding in the removal of dirt and debris. Enzymes, on the other hand, are biological catalysts that can break down specific substances, such as proteins, fats, or starches. In cleaning products, enzymes are often added to target and break down specific types of stains or soils. Sodium hydroxide (lye) is a strong alkaline substance that is effective in breaking down tough grease and fats due to its corrosive nature. On the other hand, citric acid, derived from citrus fruits, and plant-based surfactants are often chosen for their eco-friendly properties. While citric acid can have some degreasing properties, it may be less powerful than sodium hydroxide in tackling tough grease. Fragrances in cleaning agents serve the purpose of providing a pleasant scent. This can help mask any unpleasant odors associated with the cleaning process. Colorants in cleaning products are primarily added to provide a pleasant color to the solution. This can enhance the overall appearance of the product and make it more visually appealing. Preservatives are added to cleaning agents to prevent microbial growth and extend the product's shelf life.