GeneralChemistry

• Good in places, dry in others. Good on details, lacks big picture. Bailed halfway. (p450)
• Its hard to draw a line between chemistry and other sciences.
• The metric system was developed during the French revolution.
• 1 ml = 1cm³ or 1L = 10^-3 m³

Estimation

• The thermochemical calorie, ~ 3 J (4.184J) is the amount of energy needed to raise 1 g of water by 1C.
• To convert temperature from one scale to another you need only remember that the F degree is 100/180 C = 5/9 C and that 0C is the same as 32F.
• Granite has grains of three different substances: quartz mica and feldspar.
• Rocks are minerals (any chemical element, compound or other homogeneous material)
• Cast iron: is a mixture of iron and graphite (a form of carbon)
• Ductility is the ease at which a substance can be drawn into a wire.
• Iron readily combines with oxygen in moist air to form iron rust. whereas an alloy of iron with chromium and nickel (stainless steel) is found to resist rusting.
• Most bond lengths in molecules lie between 1 and 4 Angstroms (1A = 1e-10 m)
• Equilibrium is not a situation where nothing is happening, but rather a situation in which opposing reactions are taking place at the same rate so there is no overall change.
• Sublimation is the direct transition from solid (crystal) to gas or vice-versa.
• One atmosphere is ~100 kN m^-2.
• The g-factor of a proton (5.5855) is a surprising value and is evidence that the proton has complex structure and is not a simple particle.
• Cation is attracted to the cathode (the negatively charged terminal); anion, which is a negatively charged atom or molecule is attracted to the anode (the positive terminal).
• Avogadro's number is defined as the number of C-12 atoms in 12g of carbon 12. 6e23.
• Elements in the same group are called congeners
• A triple bond in the N₂ molecule is extremely strong, making N₂ very stable.
• The power of attraction for the electrons in a covalent bond is called the electronegatively of the element.
• Fluorine is by far the most electronegative element, with oxygen in 2nd place, nitrogen and chlorine in 3rd.
• Hydrogen is found in most of the substances that constitute living matter, and in many inorganic substances. There are more compounds of hydrogen known that of any other element, carbon being a close second.
• The crystal of graphite can be described as built of giant flat molecules, loosely held together in a pile.
• Elementary Nitrogen occurs in nature in the atmosphere, where it makes up 80% by volume. It is a colorless, odorless, tasteless gas of N₂ molecules.
• Oxygen is the most abundant element in the earths mantle. 90% of water 20% of air and nearly 50% of the common minerals (silicates)
• Fluorine is the most reactive of all elements. Substances such as wood and rubber bursts into flames when held in a stream of fluorine.
• The hydrocarbons are compounds of hydrogen and carbon alone. Methane CH4 is an example. Natural gas is usually about 85% methane. Gasoline is a mixture of C₇ H₁₆ and C₉ H₂₀ Kerosene a mixture of C₁₀ H₂₂ and C₁₆ H₃₄ Lubricating oils "Vaseline" and solid paraffin are mixtures of still larger molecules
• lime is calcium oxide (CaO)
• Benzene rings of 6 carbon atoms are often shown simply as a hexagon. Organic chemists also drop the attached hydrogen atoms.
• Benzene and its derivatives are extremely important substances. They are used in the manufacture of drugs, explosives (TNT) and many other substances.
• Basic (that is, it can add protons)
• An alcohol is obtained from a hydrocarbon by replacing one hydrogen atom by a hydroxyl group (-OH). Eg: methane CH4 gives methyl alcohol CH3-OH (causes blindness), and ethane C2H6 gives ethyl alcohol C2H5-OH (which is the active ingredient in alcoholic beverages.
• Nearly half of all the interesting inorganic compounds involve nonmetallic elements bonded to oxygen atoms.
• Carbon monoxide is poisonous because of its ability to combine with the hemoglobin on the blood in the same way that oxygen does.
• Dry ice is solid carbon dioxide.
• Free radical is an atom or group of atoms with one or more unshared electrons which can enter into chemical-bond formation.
• Combustion is the process of combining with oxygen.
• Gases differ remarkably from liquids and solids in that the volume of a sample of gas depends in a striking way on the temperature of the gas and the applied pressure.
• Maxwell showed that according to the kinetic theory the viscosity of a gas should be independent of pressure and should increase with increasing temperature, rather than decrease. These surprising properties were verified by experiment, and the kinetic theory of gases was accepted long before a direct experimental determination of the velocity distribution function could be carried out.
• 1 cal = 4.1840 J ~ 3 J
• The heat capacity of water is unusually large.

Estimation

• The principle commercial method of production of ammonia is the Haber process, the direct combination of nitrogen and hydrogen under high pressure (several hundred atmospheres) in the presence of a catalyst.
• Waters physical properties are strikingly different from those of other substances, in ways that determine the nature of the physical and biological world.
• Ordinary water is impure: it usually contains dissolved salts and dissolved gases. The impurity that is hardest to keep out of the water is carbon dioxide, which dissolves readily from the air.
• Hard water is water containing cations of calcium, magnesium, and iron.
• Water has a very large dielectric constant.
• The unusual properties of water mentioned above are due to the power of its molecules to attract one another especially strongly. This power is associated with a the Hydrogen bond. Only the most electronegative atoms - fluorine, oxygen, nitrogen - form these bonds. Water is especially suitable to form hydrogen bonds because each molecule as two attached hydrogen atoms and two unshared electron pairs, and so can form four hydrogen bonds. The tetrahedral arrangement of the electron pairs causes these four bonds to extend in the four tetrahedral directions of space, and leads to the characteristic crystal structure of ice. It is a very open structure; each molecule is surrounded by only four immediate neighbors. This gives ice an abnormally low density. When ice melts, this structure is partially destroyed, and the molecules are packed more closely together, causing water to have a higher density than ice.
• One of the most striking proprieties of water its ability to dissolve many substances, forming aqueous solutions. Solutions are very important kinds of matter. The ocean is an aqueous solution that contains thousands of components. It was in this solution that the first living organisms developed, and from it that they obtained the ions and molecules needed for their growth and life. With time, organisms were evolved that could leave this aqueous environment, and move out onto the land and into the air. They achieved this ability by carrying the aqueous solutions with them, as tissue fluid, blood plasma, and cellular fluids containing the necessary supply of ions and molecules.

WhoWeAre

• Air is a gaseous solution of nitrogen, oxygen, carbon dioxide, water vapor and the Nobel gases.
• An acid is a hydrogen-containing substance that dissociates on solution in water to produce hydrogen ions (protons). A base is a substance containing hydroxide ions (OH-) that dissociates in water as the hydroxide ion. Acidic solutions have a characteristic sharp taste, due to the hydronium ion H20+, and basic solutions have a brackish (?) taste, due to the hydroxide ion. An acid is a proton donor a base is a proton receptor.
• Pure water does not consist of simply H20 molecules, but contains hydronium and hydroxide ions in concentration 1e-7 moles per liter. This has been found out by the electrical conduction of water. Pure water with no ions would not conduct electricity. Instead of saying that the concentration of hydrogen ion in pure water is 1e-7 M, we say that the pH of water is 7.
• The process of extracting a metal from the ore is called winning the metal. Refining is the purification of the metal that has been extracted from the ore. Metallurgy is the science and art of winning and refining metals.
• The rate of many reactions at room temperature is approximately doubled for every 10C increase in temperature.
• Little is known about the fundamental nature of catalytic activity and searches for catalysts is largely empirical. There is some evidence that some catalysts have a structure that leads to a strong interaction with the activated complex and only weak interaction with the reactants and products. This decreases the activation energy.
• Most of the chemical reactions in living organisms are catalyzed by certain protein molecules called enzymes.
• 80 of the ~137 elementary substances are metals.
• Modern civilization is based on iron and steel. The importance of these alloys is primarily due to their hardness and strength, which are a consequence of the presence in the metals of very strong bonds between atoms.
• In metals each atom has a large number of neighbors.
• The chemical properties of the transition elements do not change so strikingly with atomic number as do those of the other elements.
• Metals are malleable. When a non-metal eg: sodium chloride is deformed such that the ions are displaced by one atomic distance, then the sodium ions become adjacent to sodium ions and chlorine ions become adjacent to chlorine ions which causes the crystal to break. In a metal, the atoms are all of the same kind, and any atom can form bonds with any other.
• A boundary between crystal grains can serve as a barrier to the motion of dislocation in the metal crystal, and in this way can decrease the plasticity and increase the hardness of a metal. If a piece of copper is hammered until the large crystal grains are broken up into small grains, the crystal boundaries may interfere with slip by stopping the motion of dislocations. This is the mechanism of the hardening of copper and other metals by "cold work".
• Silicon plays an important part in the inorganic world, similar to that played by carbon in the organic world. most of the rocks that compose the earths crust are composed of silicate minerals, of which silicon is the most important constituent. Carbon is important b/c it can form carbon-carbon bonds, permitting complex molecules. Silicon does a similar thing, but it Si not bonded to itself but to Oxygen.
• Metallic iron is greatly strengthened by the presence of a small amount of carbon. The ores of iron are usually first roasted, to remove water, decompose carbonates, and to oxidize sulfides. They are then reduced with coke, in a structure called a blast furnace. Cast iron is cheap, but low strength. It is usually converted into steel or wrought iron.
• Steel is a purified alloy of iron, carbon, and other elements. It is manufactured in a liquid state.
• Alnico is a strong ferromagnetic alloy of aluminum, nickel, cobalt, and iron. It is used for making permanent magnets.
• Gold is the most malleable and ductile of all metals.
• Oxygen is practically transparent to visible light, but strongly absorbs in the far UV.
• The ozone layer absorbs practically all the UV light from sunlight before it reaches the surface of the earth. If the UV light were not blocked life on earth (in its present form) could not exist.
• Iron wire or sheet is galvanized by cleaning with sulfuric acid and then dipping in molten zinc. a thin layer of zinc adheres to the iron.
• Chromium was not known to the ancients. Stainless steel contains ~15% chromium and 10% nickel.
• Organic chemistry is the chemistry of the compounds of carbon.
• One of the most important sources of organic compounds is petroleum (crude oil).
• The characteristic properties of rubber are due to the fact that it is an aggregate of very long molecules, intertwined with one another in a random way.
• Carbohydrates are substances with general formula CX(H20)Y. They occur widely in nature. The simpler carbohydrates are called sugars and the complex ones are called polysaccharides. Important polysaccharides include starch, glycogen, and cellulose (the structural element of plants).
• The human body does not consist of cells alone. There are also bones, which have been laid down as the excretions of bone-making cells. The bones consist of inorganic calcium molecules and collagen which is a protein.
• Proteins are probably the most important substances in plants and animals. They are molecules with very large molecular weight: 1e4 to 1e7. All proteins are nitrogenous substances, containing ~15% nitrogen, together with carbon, hydrogen, oxygen and often other elements.
• When proteins are heated in acidic or basic solutions they produce substances called amino acids.
• Proteins are an important part of food. They are digested by the stomach and intestines, being split into amino acids. These smaller molecules are able to pass through the walls of the stomach and intestines into the blood stream, where they are carried to the tissues, where they may serve as building blocks for the manufacture of the bodies proteins. Carbohydrates are split into simple sugars in digestion and then pass into the blood stream. The sugars are converted in the liver into glycogen, an important source of energy for animals. Glycogen combines with oxygen to form C02 and water + energy, part of which can be used for doing work and part to keep the body warm. The nitrogen of the protein molecules that are town down is eliminated in urine.
• Nine amino acids are essential to man. It is not enough, however, that the diet contain proteins that provides these 9 amino acids, and sufficient supply of carbs and fats to provide energy. Other substances both inorganic and organic are also essential to health. The inorganic requirements are sodium, chloride, potassium, calcium, magnesium, iodine, phosphorus and several transition metals. The other organic requirements are called vitamins.
• The amino acids are either left or right handed. A most extraordinary fact is that only one of the two parities of each of the amino acids has been found to occur in plant and animal proteins; only the left handed one. No one knows why.
• DNA: A (adenine) and T (thymine) can form two hydrogen bonds with one another where as C (cytosine) and G (guanine) can form three.
• Hormones are substances that serve as messengers in the body.
• One Curie of any radioactive substance is an amount of substance such that ~3e10 atoms undergo radioactive decay per second. The Curie is a large unit. One curie of radium is ~1g of the element.
• Carbon-14 is being made at a steady rate in the upper atmosphere. Cosmic-ray neutrons transmute N-14 into C-14. The radiocarbon is oxidized to form C02, which is mixed in the atmosphere with nonradioactive co2. The steady state concentration of c-14 atoms in the atmosphere is 1e-12. C02 is absorbed by plants with fix the carbon in their tissues. Animals that eat the plants also fix the carbon, containing 1e-12 part radiocarbon. When a plant or animal dies, the amount of radioactivity of the carbon in its tissues is determined by the amount of radiocarbon present, which is the steady state amount in the atmosphere. After 5760 years, half the c-14 decays.
• The nucleonic density is found to be constant with value, 0.3 nucleons per fm³, it drops to zero over the radio scale of 2fm. The radius is proportional to the cube root of the nucleon number, suggesting that the nucleons are packed together in a way resembling a liquid rather than a gas.