Video Script: Elements, Compounds, Atomic Structure, Chemical Bonds, and Metabolism

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In chemistry, we distinguish between elements and compounds. Elements are pure substances made of only one type of atom, like oxygen gas which contains only oxygen atoms. Compounds, on the other hand, are made of two or more different elements that are chemically bonded together, such as water which contains both hydrogen and oxygen atoms. Atoms are composed of three main subatomic particles. In the nucleus at the center, we find protons which carry a positive charge, and neutrons which have no charge. Orbiting around the nucleus are electrons, which carry a negative charge. The number of protons determines what element the atom is, while the electrons are responsible for chemical bonding. Covalent bonds form when atoms share electrons. In nonpolar covalent bonds, like in chlorine gas, both atoms have equal electronegativity, so electrons are shared equally. In polar covalent bonds, like in water, oxygen is more electronegative than hydrogen, so electrons spend more time near the oxygen atom, creating partial charges. Dehydration synthesis and hydrolysis are opposite chemical processes. In dehydration synthesis, two smaller molecules combine to form a larger molecule by removing a water molecule. This process builds complex molecules like proteins and carbohydrates. Hydrolysis does the reverse - it breaks down large molecules into smaller ones by adding water, which is essential for digestion.