Physical Science Reviewer PDF

 **Physical Science** Lesson 1.The Light Elements Bigbang Nucleosynthesis - the process where light elements were formed Hydrogen and Helium- the first light elements to be formed Rapid drop of temperature from 1032 to 109 Quarks and Gluons- condensed into nucleons whi...

 **Physical Science** Lesson 1.The Light Elements Bigbang Nucleosynthesis - the process where light elements were formed Hydrogen and Helium- the first light elements to be formed Rapid drop of temperature from 1032 to 109 Quarks and Gluons- condensed into nucleons which formed the light elements Lesson 1.2 The Heavy Elements Stellar Nucleosynthesis - the formation of heavy elements by fusion of lighter nuclei in the interior of stars. Nebulas - cloud of Hydrogen and Helium Protostar - mass of H and He Stars can only produced elements up to Iron Lesson 1.3 Formation of Elements heavier than Iron Supernova nucleosynthesis - the explosive death of star; the creation of new elements based on the intensity of the burst Extreme temperatures and Abundant neutrons - Two key characteristics of Supernova explosion Neutron capture - when the nuclei captures a electrically neutral neutron to form heavier elements than iron Lesson 1.4 Chemical Elements and Isotopes in the Universe Isotopes -is a form of an element that has the same atomic number of the original element but with different atomic mass or mass number. Stable Isotope - are not radioactive Unstable Isotope - are radioactive;decays and emits positron and neutrino to form a new element Positron - same mass as the electron but its charge is positive Neutrino - massless and has no charge Lesson 2.1 The Atomic Theory: From the Ancient Greeks up to the Present Empedocles\' Theory - proposed that there were four fundamental substances. These substances constitute all matter. Democritus\' Theory - he claimed that everything is made up of atoms.;he called the very tiny pieces of matter "atomos" which means indivisible ; the atom is the smallest possible piece of matter. Aristotles\' Theory accepted the ideas of Empedocles and even added his own idea that the four substances could be transformed into other substances. he associated the four fundamental elements-earth, water, air and fire with four qualities: hot, moist, cold and dry. Alchemys\' Theory of Matter based on Aristotles\' theory of two pairs of opposed qualities and the four elements produced by pairwise conjunction of the four qualities. ; when these elements interchange qualities , they produce other substance. Lesson 2.2 The Structure of the Atom John Dalton - proposed an atomic theory about indivisible building blocks of matter called atoms; atoms are spherical in shape and are always in motion. Four Main Concepts of Dalton\'s Atomic Theory A. matter is composed of tiny, indivisible particles called atoms. B. B. all atoms of the same element are identical in mass and properties. C. compounds are formed by a combination of two or more different kinds of atoms. D. A chemical reaction is a rearrangement of atoms. Scientific Laws About Chemical Reactions A. 1\. Law of Conservation of Mass - Antoine Lavoisier in 1789 - This law states that the total mass in a chemical reaction remains constant B..Law of Definite Proportions - Joseph Louis Proust in 1799 \- based on this law, if a compound is broken down into constituent elements, then the masses will always have the same proportions C. Law of Multiple Proportions - John Dalton -this law states that if two elements can be combine to form a number of possible compounds, then the ratios of the masses of the second element, which combines with a fixed mass of the first element, will be ratios of small whole numbers. Joseph John Thomson aka J.J. Thomson - proposed the "plum pudding" model of divisible atom - discovered the electrons Ernest Rutherford - the model atom has a very small positively-charged nucleus that contains most of the mass of the atom. - discovered the protons through his Gold Foil Experiment Niels Bohr - a planetary model for the hydrogen atom. James Chadwick - the nucleus of an atom contains neutrons, electrically neutral particles with a mass similar to that of a proton. - discovered the neutrons Quantum Mechanical Model A. Quantum - any of the very small increments or parcels into which many forms of energy are subdivided B. electrons occupy orbitals, volume of space around the nucleus with a high probability of finding the electron C. energy levels are made up of sublevels D. each sublevel contains a set of orbitals E. no orbital can contain more than two electrons Lesson 2.2 The Synthetic Elements Synthetic or Artificial elements - elements with atomic numbers 99-118. - they are radioactive Radioactivity -the result of the random and spontaneous breakdown of the unstable nucleus of an atom. -this breakdown is called radioactive decay Types of Radioactive Decay A. Alpha Radiation or Alpha Decay - happens in larger, heavier atoms where two protons and two neutrons are emitted. B. Beta Radiation or Beta- Decay -occurs in isotopes with too many neutrons in the nucleus. C. Positron Emission (β˖decay) - an isotope with too many protons in the nucleus undergoes Beta + radioactive decay. C. Electron Capture - the electron from the innermost shell is absorbed by the nucleus. D. Gamma Radiation or Gamma Decay - this does not involve any change in the atomic number or mass number. The Production of Artificial Elements Neutron Bombardment - the process in which the stable isotopes are hit by neutrons in a small research scale nuclear reactor. The Trans-uranium Elements \- the synthesis of man-made or atificially-prepared elements ( atomic number 93-112). Two Methods A. bormbarding the heavy atomic nucleus with a smaller ionized atom particle in an ion particle accelerator B. neutron bormbardment in a nuclear reactor III\. Bonding and Physical Properties of Matter Lesson 3.1 Ionic, Covalent and Metallic Bonds Ionic Bond - are formed when a metal reacts with a nonmetal - donation of electrons. - the one that donated valence electrons becomes positively-charged ion (cation) while the atom that gained electrons becomes negatively-charged ion or anion. Covalent Bonds- sharing of electrons - non-metal to non-metal chemical bond one, two or three pairs of electrons may be shared Two types of Covalent Bond A. Non-polar Covalent Bonds - Equal Sharing of electrons B. Polar Covalent Bonds - Unequal sharing of electrons Metallic Bonds -the metallic cations are attracted to delocalized electrons. - metal to metal bonding. Lesson 3.2 Bond Energies Bond Energy - in order to break the bonds between the atoms, energy needs to be absorbed - the energy that is needed to pull the atoms apart is called the bond dissokiiociation energy. The double and triple covalent bonds are stronger bonds. They have shorter bond lenghts. The shorter the bond length, the stronger is the covalent bonds Lesson 3.3 Properties of Ionic and Covalent Compounds Ionic Compounds A. are strongly bonded B. brittle and break into smaller pieces C. very high melting point D. very distinct three-dimensional crystal shapes E. can conduct electricity when dissolved in F. water because the ions are free to move Covalent Compounds A. have low melting point B. do not conduct electricity C. tend to be softer than ionic compounds when D. solid at room temperature IV\. Bonding and Electronegativity Lesson 4.1 Electronegativity - is the general tendency of an atom to attract electrons toward it. - the more electronegative an atom is, the easier it is for this atom to attract eletrons. Electronegativity Trend - INCREASING FROM LEFT TO RIGHT, DECREASING FROM TOP TO BOTTOM Polarity - is a physical property of compounds. - a result of the uneven partial charge in the atoms of a given compound. Lesson 4.2 Non Polar Molecules Nonpolar Molecules - they have the same electronegativity values and the same strength to attract electrons. \- the electron is equally shared by the two atoms. Lesson 4.3 Polar Molecules Polar Molecules or Dipole - electrons are attracted more to one end. \- the molecule has a slightly positive and a slightly negative end. Lesson 4.4 Bond Character Pauling scale - a scale developed by Linus Pauling in which fluorine has the highest electronegativiy value of 4.0. Degree of Polarity - is determined by the ectronegativity difference between the two bonded atoms. E. Intermolecular Forces Intermolecular Forces - the strength of these forces determines the state of the substance. - solid, liquid, or gas- at room temperature. Lesson 5.1 Types of Intermolecular Forces Ion-Dipole forces - when an ion and a polar molecule ( a dipole ) attract each other. Hydrogen Bonding - a special type of dipole-dipole interaction. - it involves hydrogen and an electronegative atom such as nitrogen, oxygen, or fluorine. Van der Waals Dipole-Dipole Forces - the attractive forces between polar molecules, or those have dipole moments. - result when the positive region of one molecule becomes attracted to the negative region of a second molecule. Dispersion Forces (london Forces) - Fritz W. London -these forces act on all molecules and they are considered as the weakest intermolecular forces. - the only forces between two nonpolar molecules. Lesson 5.2 Intermolecular Forces and Properties of Substance Properties of Liquids A. Surface Tension - the amount of energy that is needed to the liquid surface. -directly proportional to the intermolecular forces between the particles of a liquid. B. Capillarity - the ability of the liquids to rise in a narrow tube because the adhesive foces are greater than the cohesive forces C. Boiling and Melting Points - the greater the molecular weight the higher is the melting point of the substance. As the kinetic energy of the molecules decreases, they become less active but the London forces increases. -the shape of the molecule also affects the strength of the dispersion forces. D. Viscosity -the resistance to flow. This is exhibited by both gases and liquids. - liquids with strong intermolecular forces have higher viscosities. Properties of Solids A. Crystalline Solids - are those that have a well-defined shape due to the arrangement of their atoms, molecules, or ions. B. Amorphous Solids - those which are disorganized. VI\. Chemical Reactions Lesson 6.1 Understanding Chemical Reactions Chemical Reaction - a process that involves rearrangement of the molecular or ionic structure of a substance, as opposed to a change in physical form or a nuclear reaction. Two sets of substance involved in a chemical reaction: A. Reactants - present before the chemical reaction took place B. Products - resulting substances Lesson 6.2 Types of Chemical Reactions Composition or Combination Reaction - This reaction takes place when two or more elements combine to form a more complex molecule. Decomposition Reaction - One substance, usually a compound breaks down to form two or more subtances which may be elements or compounds. Single-Replacement Reactions - subtitution or replacement reaction, one element reacts by replacing another element in a compound. Double-Replacement Reaction - involves ionic reactions, the positive ion of one compound exchanges with the positive cation of another compound. - also known as metathesis. Lesson 6.3 Evidences of Chemical Reactions Energy and Chemical Reactions A. Exothermic Reaction - is a chemical reaction that involves the release of energy. - the root word "thermic" refers to heat and the prefix "exo" means out of. B. Endothermic Reaction - the prefix "endo" means into.-The word endothermic refers to the absorption of heat. Lesson 6.4 Energy of Chemical Reactions Activation Energy - refers to the certain amount of energy that is needed for a chemical change to occur. - to get the bonds into a state that allows them to break, the molecule must be contorted (deformed, or bent) into an unstable state called the transition state. Lesson 6.5 Rates of Chemical Reactions Reaction Mechanism - series of steps before the product/s is/are formed. such as burning of wood, burning of paper, digestion of food, souring of millk, and corroding of metal. Rates of Chemical Reactions - a measure of how fast the reactants turns into product. Kinetics - the study of reaction rates. Collision Theory - shows the relationship between particle collisions and reaction rate. - the more collisions there are, the faster the rate of the chemical reaction. Factors Affecting Rates of Reaction A. Concentration - substances with higher concentration have more particles available for collisions. If there are more collisions, then more products would also be formed. B. Particle Size - the greater the surface area the greater also would be the collision between the particles. the more collisions, the faster also is the rate of reaction. C. Surface Area - refers to how much of the amount of material is exposed. D. Temperature - the molecules of a substance become more active as the temperature increases. The more collisions, the faster, too, is the rate of reaction. E. Catalyst - a substance that speeds up the rate of reaction. - lowers down the activation energy required so that the molecules of the of the reactants can already start colliding each other. 1\. Heterogenous Catalyst- a catalyst that exists in a different state than the reaction it catalyzes. 2\. Homogenous Catalyst- the same physical state as the one catalyzes. Lesson 6.6 Other Sources of Energy Renewable resources - those that can be replenished in a short period of time. Nonrenewable resources - resources that are not easily replenished by the environment. Fossil Fuels - are burried combustible geologic deposits of organic materials formed from decayed plants and animals that have been converted by exposure to heat and pressure in the earth\'s crust over hundreds of million of years. Carboniferous Period - the fossil fuels were formed which is part of Paleozoic Era \- derived from the word carbon, the basic element in coal and other fossil fuels. Geothermal - comes from "geo" which means earth and "thermal" which refers to heat. - as the distance below earth\'s crust increases, the temperature also increases. Hydroelectric - another source of energy is water. - it is the kinetic energy of moving water that that is used to generate electricity. Batteries - chemical energy can be stored in batteries. - chemical reactions takes place inside the battery if there is a flow of electrons. Different Types of Batteries A. Alkaline battery - the electrodes are zinc and manganese oxide. the electrolyte is alkaline paste. B. Lead-acid battery - used in automobiles. -the electrodes are made of lead and lead oxide. the electrolyte is a strong acid. C. Lithium battery - used in cameras for the flash bulb. - made with lithium, lithium iodide, and lead iodide. - it can supply surges of electricity for the flash. D. Lithium-ion battery - the battery found in laptop computers, cellular phones and other high-use portable equipment. E. Nickel-cadmium battery - electrodes are nickel hydroxide and cadmium. the electrolyte is potassium hydroxide. F. Zinc-carbon battery or standard carbon battery - zinc and carbom are used in all regular or standard AA, C, and D dry-cell batteries. -electrodes are made of zinc and carbon, with a paste of acidic materials between them serving as the electrolyte. Solar Cells - also called photovoltaic cells (or PV Cells) - they are used in calculators and even space crafts. - were first used in US space satellites. Biomass - usually equated with garbage. -sometimes tapped directly at the landfill with decaying waste products. Landfill gas - gas collected when a garbage decomposes and is used to make electricity. Biogas or Biofuel- the fuel gas resulting from biomass. - a mixture of 65% methane and 35% carbon dioxide. lighter than air, and it produces twice as less calories by combustion with equal volume of natural gas. VII\. Stoichiometry Lesson 7.1 Stoichiometry Stoichiometry - refers to measurement based on the quantitative laws of chemical combination Formula Mass - the term used for compounds that are made up of primarily IONIC BONDS. Molecular Mass - the term used for compounds that are composed of molecules and have primarily COVALENT BONDS. The Mole - Chemists are able to count atom and molecules by relating number to mass. - they have created a counting unit called mole. Avogadro's number - 6.02x 1023 Percentage Composition From Formulas - percent is defined as parts per hundred to find the percentage composition of a compound, you can use grams for mass units. Calculations of Formulas From Experimental Data The formula can only be obtained after experimentally determining: a. the elements that comprise the compound b. the proportions by weight of the elements in the compound c. the relative molecular weight of the compound Empirical Formulas - used to calculate the simplest ratio of a compound You can determine the empirical formula of a compound based on: a. mass relations of elements obtained from experimental data b. percentage composition of the compound Lesson 7.2 Calculations with Balanced Equations Mole-to-Mole Conversion - If the number of moles of one substance is given in the problem, you can determine the number of moles of any of the other substances in the reaction by using a mole conversion factor based on the coefficients in the balanced equation. Moles-to-Grams Conversion \- In order to convert moles to grams or grams to moles, you have to make use of the molar mass of the given compound. Mass-to-Mass Conversion - If the problem asks for the mass in grams of one substance and the mass of another substance is given, follow these steps. Step 1. Change the mass in grams of the given substance to moles using its molar mass. Step 2. Then calculate the number of moles othe other substance using the mole relationship. Step 3. Finally, the moles of the unknown substance can be changed to grams using its molar mass. Lesson 7.3 Limiting and Excess Reagent/Reactant Limiting Reactant or Limiting Reagent - the reactant or reagent that limits the amount of product formed because it was already totally consumed while a reaction is taking place. Excess Reactant or Excess Reagent - the other reactant that is in excess. Theoretical yield - the amount of product that is expected to be formed based on calculations. Actual yield - the amount of product actually produced as a result of the reaction. Percent yield - the ratio between the actual yield and the theoretical yield. Formula: Percentage Yield = actual yield/ theoretical yield x 100%