Physical Science PDF: The Life Cycle of Stars

`Physical Science THE LIFE CYCLE OF STAR Big Bang: The big bang theory, a cosmological model that describes how the universe started its expansion about 13.8 billion years ago, states that the universe continues to move and expand. How did big bang explain t...

`Physical Science THE LIFE CYCLE OF STAR Big Bang: The big bang theory, a cosmological model that describes how the universe started its expansion about 13.8 billion years ago, states that the universe continues to move and expand. How did big bang explain the formation of the unisverse: The universe expanded rapidly from this point, and it continues to expand, causing galaxies to move apart. This is observed through redshift, where light from distant galaxies stretches as they move away. Star - Stars are primarily made of hydrogen and helium. These elements undergo nuclear fusion in the star's core, producing heavier elements like carbon, oxygen, and others, along with energy that makes the star shine. Stellar Formation - The star formation theory states that stars formed when gravity acted on the particles expanding the universe Stellar Nucleosynthesis - production of nuclei heavier than hydrogen in stars CNO Process: Fusion of hydrogen into helium using carbon, nitrogen, and oxygen as catalysts in stars more massive than the Sun. Big Bang Nucleosynthesis: Formation of light elements (hydrogen, helium, and trace amounts of lithium) during the early moments of the universe. Neutron Capture: Process where atomic nuclei capture neutrons to form heavier elements; includes s-process (slow capture) and r-process (rapid capture). Proton-Proton Chain: Fusion of hydrogen into helium primarily in stars like the Sun, involving a series of reactions that convert protons into helium. Stellar nurseries form from dense molecular regions Protostars are formed when these regions collapse Big Bang nucleosynthesis - forms light elements like hydrogen, helium Stellar Nucleosynthesis - it is the production of nuclei heavier than hydrogen in stars Formation of Elements heavier than Iron - The massive stars that end up as supernova are manufacturers of elements heavier than iron - Like gold(Au), silver(Ag), lead (Pb), and mercury(Hg) require the very special conditions of pressure and heat that exist inside a supernova during those few seconds of collapse - Supernovas distributer if elements to the universe because of explosion Stellar evolution - refers to the process in which a star changes through its lifetime Proving Stellar Evolution and Nucleosynthesis 1. The discovery of interstellar gas and dust in the early 1900s 2. The study of different stages of stellar evolution happening throughout the universe - Infrared radiation(IR) can be detected from different stages of stellar evolution - LIFE CYCLE OF A STAR Stellar Nebula: A massive cloud of gas and dust where stars are born. Gravity pulls the particles together, and once dense enough, nuclear fusion ignites, forming a star. Protostar: The early stage of a star's formation where the gas and dust condense under gravity, but nuclear fusion hasn't fully started yet. Main Sequence: The stable period in a star's life where hydrogen is fused into helium in the core. This is the longest phase, and our Sun is currently in this stage. Red Giant/Supergiant: As the hydrogen in the core depletes, the star expands and cools, becoming a red giant (if medium-mass) or supergiant (if massive). Planetary Nebula/Supernova: For medium-mass stars, the outer layers are shed, forming a planetary nebula. For massive stars, they explode in a supernova, releasing enormous energy. White Dwarf, Neutron Star, or Black Hole: White Dwarf: The remnant of a medium-mass star. It slowly cools and fades over time. Neutron Star: If the star was massive enough, its core collapses into an incredibly dense neutron star. Black Hole: If the star was extremely massive, its core collapses to a point of infinite density, forming a black hole. THE CONCEPT OF ATOMIC NUMBER LED TO THE SYNTHESIS OF NEW ELEMENTS IN THE LABORATORY Atomic number - number of protons in the nucleus of each atom of an element is called the atomic number(Z) - In a neutral atom the number of protons is equal to the number of electrons, so the atomic number also indicates the number of electrons present in the atom. Periodic table - organized array of all the chemical elements in order of increasing atomic number. - There are 94 elements that naturally occur in the earth and 24 elements are synthetic Henry Gwyn- Jeffrey’s Moseley - demonstrate that the atomic number, the number of protons in an atom, determines most of the properties of a component - In 1913 Moseley published a paper on the arrangement of the elements in the periodic table based on their atomic number. He used X-ray spectroscopy to work out the atomic number of an element - gaps corresponded to the atomic numbers 43, 61, 85 and 87. - These elements were synthesized in the laboratory through nuclear transmutations, - In 1919 Rutherford successfully administered a nuclear transmission reaction , a reaction involving the transformation of one element into another element LEWIS DOT STRUCTURE Valence Electron - refers to the electrons found in the outermost shell of an orbital; that occupy the shell with the highest value of n. Those are also ones that participate in chemical reaction Octet rule atoms tend to gain lose or share electrons until they are surrounded by eight valence electrons Multiple bonds - a shared electron pair constitutes s single covalent bond, generally referred to simply as a single bond Tripple bond corresponds to the sharing of three pairs of electrons, such as in the N2 molecule Properties of Molecules based on Polarity - The properties of the molecules are related to their polarity  - Forces of attraction play significant roles to almost all properties of substances, including solubility melting point and boiling point, - Molecules with partially positive ends attracted to the partially negative ends of other molecules Dipole-dipole forces - polar molecules , this is due to the interaction of the positive pole of one molecule with the negative pole of another Nonpolar molecules, however, do not have positive or negative ends, therefore attraction is very miniman The strength of attraction between molecules affect properties such as solubility, meting point and boiling point Solubility - refers to the maximum amount of solute that dissolves in a given quantity of solvent Hydrophilic - interact with water Hydrophobic - repel water If both Philic and phobic its amphiphilic molecules like soap Immiscibility - never fully mix Miscible substance fully mix in all portion Intermolecular forces Intramolecular forces - type of attractive force; attraction of atoms within molecule Intermolecular forces -force between molecules, which holds them together TYPE OF INTERMOLECULAR FORCES Ion Ion Interaction - strongest intermolecular force. Between oppositely charged ions, there is ion ion contact London Dispersion Forces (LDFs) - These are the weakest , present in betweel all electrically neutral molecules polar and non polar molecules Dipole- Dipole forces -between partially positive end of one HCI molecule and the partially negative end of another HCI Ion-Dipole - this result from the electrostatic attraction of molecule containing a dipole and an ion Hydrogen Bonding - attractive force that exist when hydrogen is bonded to F, O or N CARBOHYDRATES AND PROTEINS 1. Biological Macromolecules-They are composed of many small organic molecules that link up to form a long chain. 2. Carbohydrates- are polymers composed of sugar molecules linked together in long chains 3. Monosaccharide-(simple sugar) a carbohydrate with three to seven carbon atoms. 4. Disaccharide- A carbohydrate composed of two monosaccharides. 5. Polysaccharide-A carbohydrate that is a polymer of monosaccharides. - Carbohydrates are also called saccharides which means sugar. he simplest carbohydrates are monosaccharides. - Disaccharides are two monosaccharides joined together while polysaccharides are complex carbohydrates. When these saccharides react with water, they can be completely hydrolyzed to yield monosaccharide units.  Carbohydrates are chains of small organic molecules with a 1:2:1 mole ratio of carbon, hydrogen, and oxygen. Lipids - are organic molecules that are insoluble in water because of their lack of many functional groups Fat molecule- two main component glycerol and fatty acid LIPIDS TYPE Phospholipids Fats Oils Steriods Waxes