Basics of Physical Chemistry [PPT]

Aug 20, 2019
  • Composition of Matter - Everything in the universe is composed matter. Matter is anything that occupies space or has mass Mass - quantity of matter an object 'Weight pull of gravity on an object Volume
  • Elements Pure substances that cannot be broken down chemically into simpler kinds of At Rn matter More than occurring) 100 elements (92 naturally Mg 40 La s-block elements p•btock elements d-biock elements t: f-btock elements V cr Mn Fe co Ni cu Nb Mo Ru Rh Pd Ag Cd Ta W Re os Ir Pt Au Hg Tl Db Sg Bh H' Mt 'Jun uuu 'Jub c Ge uuq• F Ne As Sb se
  • 90% of the mass of an organism is composed of 4 elements (oxygen, carbon hydrogen and nitrogen) Each element unique chemical symbol Consists of 1-2 letters First letter is always capitalized 6.4 Alornlc number 2 —He Chemkal symbol Atomic mms 9 F Fluorite 19 oo 4 10 Ne Neon 20. IJ
  • Atoms The simplest particle of an element that retains all the properties of that element Properties of atoms determine the structure and properties of the matter they compose Our understanding of the structure of atoms based on scientific models, not observation Nucleus Ele€tron Energy l*'eb
  • The Nucleus Central core Consists of positive charged protons and neutral neutrons Positively charged Contains most of the mass of the atom
  • The Protons All atoms of a given element have the same number of protons Number of protons called the atomic number Number of protons balanced by an equal number of negatively charged electrons Oxygen 15.9994 (He)2s'2p8 Oxygen atom 8 Protons 8 Neutrons 8 Electrons
  • The Neutrons The number varies slightly among atoms of the same element Different number of neutrons produces isotopes of the same element Nontadloacuve carbon-12 6 eleorons 6 protons 6 neutr ons lwtopes of Carbon Nonradioactrve carbon-13 6 electrons 6 protons 7 neutrons Radioactrve carbon-14 6 electrons 6 protons B neutrons
  • Atomic Mass Protons & neutrons are found in the nucleus of an atom Protons and neutrons each have a mass of 1 amu (atomic mass unit) The atomic mass of an atom is found by adding the number of protons & neutrons in an atom
  • The Electrons Negatively charged high energy particles with little or no mass Travel at very high speeds at various distances (energy levels) from the nucleus
  • Electrons in the same energy level are approximately the same distance from the nucleus Outer energy levels have more energy than inner levels Each level holds only a certain number of electrons D)RCt1
  • Energy Levels Atoms have 7 energy levels The levels are K (closest to the nucleus), L, M, N, O, P, Q (furthest from the nucleus) The K level can only hold 2 electrons Levels L - Q can hold 8 electrons (octet rule)
  • Periodic Table Elements are arranged by their atomic number on the Periodic Table The horizontal rows are called Periods & tell the number of energy levels Vertical groups are called Families & tell the outermost number of electrons
  • IVA VA VIA VIP. 3 Na Mg * Lanthanide Series + Actinide Series Periodic Table of Elements Iva va 58 Ce Pr Nd Legend - click to find out more... Non-Metals Alkali Metals Li -solid Transition Metals Alkali Earth Metals Br - liquid Rare Earth Metals Other Metals Tc - synthetic Halogens Inert Elements
  • Compounds • Most elements do not exist by themselves Readily combine with other elements in a predictable fashion H3C OH Aspirin
  • A compound is a pure substance made up of atoms of two or more elements The proportion of atoms are always fixed Chemical formula shows the kind and proportion of atoms of each element that occurs in a particular compound
  • Molecules are the simplest part of a substance that retains all of the properties of the substance and exists in a free state Some molecules are large and complex methane CFC
  • Chemical Formulas Subscript after a symbol tell the number of atoms of each element • 1420 has 2 atoms of hydrogen & 1 atom of oxygen Coefficients before a formula tell the number of molecules • 302 represents 3 molecules of oxygen or (3x2) or 6 atoms of oxygen
  • The physical and chemical properties of a compound differ from the physical and chemical properties of the individual elements that compose it Water molecule H 20 Oxygen molecule 02 6.4 Sucrose molecule C'2H220'1
  • The tendency of elements to combine and form compounds depends on the number and arrangement of electrons in their outermost energy level Atoms are most stable when their outer most energy level is filled
  • Most atoms are not stable in their natural state Tend to react (combine) with other atoms in order to become more stable (undergo chemical reactions) In chemical reactions Carbon bonds are broken; atom rearranged and new chemical bonds are formed that store energy Hydrogen and Oxygen
  • Covalent Bonds Formed when two atoms share one or more pairs of electrons o O Water 0420)
  • Ionic Bonds Some atoms become stable by losing or gaining electrons Atoms that lose electrons are called positive ions
  • Atoms that gain electrons are called negative ions Because positive and negative electrical charges attract each other ionic bonds form Sodium Atom (Na) Chlorine Atom (Cl) Sodium Ion (Na+) Chiorino ion (CI—) e Transfer of Electron Protons 11 Electrcns —11 Charge protons E Ectrons Charge -17 Protcns Eledrons Charge -10 Protons Electrons Chxge +17 -18
  • Energy and Matter • Energy The ability to do work or cat change Occurs in various forms Can be converted to another form Forms important to biological systems are chemical, thermal, electrical and mechanical energy Free energy is the energy in a system that is available for work
  • States of Matter Atoms are in constant motion The rate at which atoms or molecules in a substance move determines its state SQ/id Liquid
  • Solid o Molecules tightly linked together in a definite shape O Vibrate in place • Fixed volume and shape
  • Liquids -Molecules not as tightly linked as a solid o Maintain fixed volume o Able to flow and conform to shape of container PYREX
  • Gas Molecules have little or no attraction to each other Fill the volume of the e occupied container • Move most rapidly To cause a substance to change state, thermal energy (heat) must be added to or removed from a substance
  • Energy and Chemical Reactions Living things undergo thousands of chemical reactions as part of the life process
  • Many are very complex involving multistep sequences called biochemical pathways Chemical equations represent chemical reactions Glucose (giycoiysis) Glycerol Phosphoglycetabdehyde (PGAI.) Pyruvic acid Gly, Ser, Ala. Cys Fan-y acids ++Acety CoA+Phe. Leu. lie, Thr. Lys. Trp. Tyr Asp. Onloacetic acid Citric id The Citric Acid cyclo Reactants are shown on crketoglutar»c acid Arg, His Pro left side of the equation Products are shown on the right side Succinic acid Val. Met. Ile
  • The number of each kind of atom must be the same on either side of the arrow (equation must be balanced) Bonds may be broken or made forming new compounds + H2() 1-1304 (aq) + Nitrate ion, NO Hydronium ion, I-LO
  • Energy Transfer Much of the energy organisms need is provided by sugar (food) Undergoes a series of chemical reactions in which energy is released (cell respiration) The net release of free energy is called an exergonic (exothermic) reaction Reactants O Energy is released Products Reaction Progress
  • Reactions that involve a net absorption of free energy are called endergonic (endothermic) reactions Photosynthesis is an example Most reactions in living Energy is required The pr have more energy than the reactants Reaction Progress organisms are endergonic; therefore living organisms require a constant source of energy
  • Most chemical reactions require energy to begin The amount of energy needed to start the reaction is called activation energy Exothermic Reaction Activation energy Reactants Energy given off Products Reaction progress
  • Certain chemical substances (catalysts) reduce the amount of activation energy required Biological catalysts are called enzymes Comparison of Pathways for the Decomposition of H202 c EO = 58 Eti = 4 Uncatalyzed Homogeneous Chemically processes catalyzed (I ) Enzymatically catalyzed Reaction progress
  • Enzymes are an important class of catalysts in living organisms Mostly protein Thousands of different kinds Each specific for a different chemical reaction Substrates Enzyme Product
  • Enzyme Structure Enzymes work on substances called substrates Substrates must fit into a place on an enzyme called the active site Enzymes are reusable! Active Site Substrate Enzyme
  • 6.4 Reduction-Oxidation Reactions Many of the chemical reactions that help transfer energy in living organisms involve the transfer of electrons (reduction-oxidation = redox reactions) Oxidized compound B Reduced compound A (oxidizing agent) (reducing agent) B is reduced, A is oxidized, gaining electrons losing electrons Reduced Oxidized compound B compound A
  • Oxidation reaction - reactant loses electron(s) becoming more positive 2Na + C,12 -..-..........-.+ 2NaC,l +1 Sodium Sodium ion Electron
  • Reduction reaction - reactant gains electron(s) becoming more negative 2Na + C12 2NaCl -l c12 2 e-- -...................................> Cl-- Chlorine Electrons Chloride ion
  • Solutions
  • Solutions A solution is a mixture in which 2 or more substances are uniformly distributed in another substance Solution Solvent + Solute
  • Solute is the substance dissolved in the solution Particles may be ions, atoms, or molecules Solvent is the in which substance the solute IS dissolved Water is the universal solvent Solute Sodium ion, Nav Chloride ion, Cl Water, solvent Saltwater, solution 000 00000800
  • Solutions can be composed of varying proportions of a given solute in a given solvent - vary in concentration (measurement of the amount of solute) A saturated solution is one in which no more solute can be dissolved Aqueous solution (water) are universally important to living things
  • Dissociation of water Breaking apart of the water molecule into two ions of opposite charge (due to strong attraction of oxygen atom of one molecule for H atom of another water molecule) H20 H + (hydrogen ion) + OH- (hydroxide ion) + H 20 H30 (hydronium ion) I-I 6.4 Dissociation of water molecule 1+1 Water Molecule (2 hydrogen and one oxygen atom) spilt to form negative hydroxl ion (alkaline) and r»sitive hydrogen ion (acidic) 1+1 11
  • Acids and Bases One of the most important aspects of a living system is the degree of acidity or alkalinity Hydronium ion
  • Acids Number of hydronium ions in solutions is greater than the number of hydroxide ions Chloride ions, Hydronium ions, Water molecule, H 20
  • Bases Number of hydroxide ions in solution is greater than the number of hydronium ions - NaOH Na+ + OH- Properties of Acids and Bases Litmus Indicators Litmus comos from lichens. Hydrochloric acid (an acid) Water a neutral substance) Sodium hydroxide base)
  • More basic More acidic 2 3 4 5 6 7 8 9 10 11 12 13 14 pH Scale logarithmic scale for comparing the relative concentrations of hydronium ions and hydroxide ions in a solution ranges from O to 14 Battery acid Stomach acid Apple juice Antacid (when dissolved Hand in water) soap Pure Baking soda Black coffee water Quality BAKING SODA. Drain cleaner Household ammonia • Each pH is IOX stronger than next • e.g. ph 1 is 10 times stronger than ph 2
  • the lower the pH the stronger the acid the higher the pH the stronger the base pH 7.0 is neutral
  • Buffers Control of pH is very important Most enzymes function only within a very narrow pH Control is accomplished with buffers made by the body Buffers keep a neutral pH (pH 7) 6.4 lhtffered AspirifJ TIA H4+A- HA 011-+ TIA A
  • Buffers neutralize small amounts of either an acid or base added to a solution Complex buffering systems maintain the pH values of your body's many fluids at normal and safe levels H2C03 OH - + HeC03 1120 1130 + + H20
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Gopal Ji Rai

With more than 12 years of experience in tutoring students belonging to Competitive Exam and train students for the campus recruitment test in the engineering colleges. I try to cater to them all as per their requirements. My focus is particularly based on problem-based learning. I’m also associated with LearnPick for the last 6 years.

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