Polymer" is a generic term used to describe a very long molecule consisting of structural units and repeating units connected by covalent chemical bonds.
A key feature that distinguishes polymers from other molecules is the repetition of many identical, similar, or complementary molecular subunits in these chains.
These subunits, the monomers, are small molecules of low to moderate molecular weight, and are linked to each other during a chemical reaction called polymerization.
Polymer
Author: asim /Chemical compound
Author: asim /
A chemical compound is a chemical substance consisting of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition.
The ratio of each element is usually expressed by chemical formula.
For example, water (H2O) is a compound consisting of two hydrogen atoms bonded to an oxygen atom. The atoms within a compound can be held together by a variety of interactions, ranging from covalent bonds to electrostatic forces in ionic bonds.
Real Gases
Author: asim /gas molecules attract one another
gas molecules occupy a finite volume
Both of these factors are neglected in the Ideal Gas law. Both increase in importance when molecules are close together (high P, low T)
van der Walls equation corrects for the attraction between molecules.nb corrects for the volume of gas moleculesvan der Walls constants are given
Kinetic Theory of Gases
Author: asim /1.Gases consist of particles (atoms or molecules) in continuous, random motion.
2.Collisions between gas particles are elastic.
3.The average energy of translational motion of a gas particle is directly proportional to temperature. In addition to the postulates above, it is assumed that the volumes of the particles are negligible as compared to container volume and attractive forces between particles are neglected.
Et = average kinetic energy of translationKEavgm = mass of the particleu = average velocity of the particle
from the third postulate we can formulateT = temperature in Kelvin, c = constant which has the same value for all gases.
A.Average Speed of Gas particles (find u)c = constant = R = gas constant, NA = Avogadro's #substituting for cmass times moles (NA) equals Molar Mass (MM), substituting MM and solving for u givesusing this last equation we can solve for an individual gas particle's speed rms = root mean square, which is the average square root of the speed of the individual particles.Use R = 8.3148 , in order for the units to come out in m/s
B.Grahm's Law
effusion - the flow of gas particles through a small opening or pinhole in a container.diffusion - random motion of gas particles.formulas:if the two gases are at the same temperature then:
Experimentally usually measure the time for effusion to occur, this time is an inverse of the effusion rate (lower times-faster effusion rates)
this equation was used for the separation of U238 during WWII by effusion principles.
The Ideal Gas Law
Author: asim /V=
volume (liters, cubic decimeters, milliliters, cubic centimeters).
n=
amount in moles, n = (MM = molar mass from Periodic Table).
T=
temperature, for gases must be in Kelvin, K = oC = 273.15, usually find temperature to nearest degree, so only add 273.
P=
pressure (atmospheres, millimeters of mercury, kilopascals, torr. 1 atm = 760 mm Hg = 101.3 kPa = 760 torr = 29.92 in Hg = 14.7 lb/in2, these are all at 0 oCtorr named after Torricelli - Italian scientist, first person to accurately measure atmospheric pressure, 1640
Calculation of Gas Pressure
barometer - closed manometer, take h directly.
manometer - open manometer.Pgas = Patm + P due to h mm Hg H2O is on the atmospheric side in the h part of the equation, this will effectively give the addition or subtraction from atmospheric pressure.
Relation between variables;
PV=nRTwhere R is a true constant, it is the same for all gases and is independent of P, V, n or T.
inputting standard temperature and pressure (STP) for any gas will give the same R, Avogadro's Law - the same number of particles at the same P, T, and V.
Matter and Measurements Review
Author: asim /AP ChemistryScience of chemistry dates form about 1800, chemistry is an experimental science.
1.Measured Quantities
Length
Volume
Mass
TemperatureKelvin: K= oC + 273.15Celsius: oC = K - 273.15
2.Significant Figures
significant digits: based upon the meaningful digits from the laboratory instrument, know the rules on page 13 of the textbook.
mathematics: multiplication and division addition and subtraction.
3.Conversion FactorsBased on the "bridge" between known and unknown
one step conversions
multiple step conversions
4.Types of Substances
elements: cannot be broken down into two or more simpler substances.Know symbols, location on periodic table.
compounds: contain two or more elements with fixed mass percents.sodium chloride NaCl 39.345 Na, 60.66% Cl
5.Properties of Substances:Used to identify a substance by comparing to the properties of known substances.
chemical properties
physical properties
density
solubility
specific heat: q = m ( T) (Cp)
color
6.Separation of Mixtures
distillation
chromatography
Chemical Formulas and Equations
Author: asim /I.Prediction of formulas of ionic compounds
1.Charges of monatomic ions of main group elements can be predicted from position in Periodic Table.
2.Transition metal cations can have multiple charges. You must know the common transition metals.(Table 2.4 page 62)
3.Polyatomic ions; know common ions, hand out.
Names of compounds
1.Ionic Compounds: give name of cation followed by that of anion (ends in -ide). If metal forms more than one cation, as with many transition metals, then names of ions have suffixes that are related to their ionic charges: -ous refers to the lower charge: -ic refers to the higher charge.
**The IUPAC (Stock Name) system uses Roman Numerals.**
2.Names of polyatomic ions containing oxygen- some elements form several polyatomic ions with oxygen. A series of suffixes and prefixes is used to specify the relative number of oxygen atoms.
per-........-ate
greatest number of oxygen atoms
........-ate
greater
........-ite
smaller
hypo-........-ite
smallest number of oxygen atomsThe mercurous ion is an exceptional case, it requires special attention. The formula and charge for the mercurous or mercury (I) ion is Hg2+2. Note that this ion contains two mercury atoms.
3.Binary molecular compounds (two nonmetals)Indicate number of atoms of each element using greek prefixes (page 67).
PCl3
N2O5
N2H4
Acid nomenclature
Acids- Acids are molecular compounds that contain hydrogen bonded to a nonmetal to a group of atoms that behave like a nonmetal. Acids can be either binary or ternary compounds. The names of binary acids have the form Hydro-........-ic acids. The names of ternary acids use a series of prefixes and suffixes to specify the relative number of oxygen atoms in the molecule.
per-........-ic
greatest number of oxygen atoms
........-ic
greater
........-ous
smaller
hypo-........-ous
smallest number of oxygen atoms
If only two different ternary acids exist for a given nonmetal, only the suffixes -ic and -ous are used.
HClO4
perchloric acid
HClO3
chloric acid
HClO2
chlorous acid
HClO
hypochlorous acid
Significant Digit Rules
Author: asim /1.The number of significant digits recorded for a measurement includes all of those digits known with certainty plus the first digit about which there is some uncertainty. The first digit in which there is some uncertainty is the first digit which is estimated
2.The only time significant digits must be considered is when dealing with measured quantities. You will only deal with two types of numbers, those which are part of a measured quantity and pure numbers. An example of a pure number is the number 2 when it indicates the diameter of a circle is twice the radius of a circle. Another pure number would be the number 5 when you say five people. Many conversion facts are also pure numbers like 5280 ft = 1 mi or 1 in = 2.54 cm. Pure numbers have infinite number of significant digits. The fact that pure numbers have an infinite number of significant digits means they will never be the number which limits the numbers of significant digits in the result of a calculation using measured quantities.
3.All digits which are not zeros are significant digits.
4.Any zeros between nonzero digits are significant
5.Any zeros which simply hold the decimal point in position are not significant digits. A simple test for this kind of zero is to write the quantity in scientific notation. If the zeros disappear they are not significant. A further description of these kinds of zeros would be either -
1"ending" zeros (for big numbers) which are to the right of any nonzero digit but to the left of the decimal point, or
2"leading" zeros (for small, decimal numbers) which are to the right of a decimal point but to the left of any nonzero digit.
6.In a number such as 56,500 a special effort must be made to indicate the place value to which the quantity was recorded in the event the zeros are significant. A line above a zero or below it indicates that the zero is significant and it is the first estimated digit or the last significant digit.
7."Trailing" zeros (for decimals) which are to the right of the decimal point and to the right of any nonzero digit are significant because they indicate the measurement has been carried to that degree of precision.
8.When adding or subtracting measurements you should first calculate the answer using all digits available. Then you should determine to which place value you should round your answer. To do this determine the estimated digit in each number used in the calculation (this would be the last significant digit in each number). Then, as you proceed from left to right, the first column in which you find an estimated digit should be the column or place value to which you should round off your answer.
9.In multiplication or division of measured quantities you should first perform all of the calculations involved. Then determine how many significant digits are in each of the quantities used in the calculations. Round off your answer so it has only as many significant digits as the quantity which contains the least number of significant digits.
10.When taking a logarithm the number of digits to the right of the decimal is equal to the number of significant digits in the number that you are taking the logarithm of.
AP Chemistry: Basic Knowledge
Author: asim /Elements
Symbol
+Oxidation
-Oxidation
aluminum
Al
3+
barium
Ba
2+
beryllium
Be
2+
boron
B
3+
bromine
Br
-1
cadmium
Cd
calcium
Ca
2+
carbon
C
4+
-4
cesium
Cs
1+
chlorine
Cl
-1
chromium
Cr
3+
cobalt
Co
2+, 3+
copper
Cu
1+, 2+
fluorine
F
-1
gold
Au
1+
helium
He
hydrogen
H
1+
iodine
I
-1
iron
Fe
2+, 3+
lead
Pb
2+, 4+
lithium
Li
1+
magnesium
Mg
2+
manganese
Mn
mercury
Hg
neon
Ne
nickel
Ni
nitrogen
N
-3
oxygen
O
-2
phosphorus
P
-3
platiunm
Pt
potassium
K
1+
silicon
Si
silver
Ag
1+
sodium
Na
1+
strontium
Sr
2+
sulfur
S
-2
tin
Sn
2+
zinc
Zn
2+
POLYATOMIC IONS
phosphate
PO43-
ammonium
NH41+
acetate
CH3COO1-
hydroxide
OH1-
nitrate
NO31-
carbonate
CO32-
sulfate
SO42-
chlorate
ClO31-
chromate
CrO42-
dichromate
Cr2O72-
peroxide
O22-
cyanide
CN1-
permanganate
MnO41-
oxalate
C2O42-
hydrogen phosphate
HPO42-
dihydrogen phosphate
H2PO41-
thiocyanate
SCN1-
thiosulfate
S2O32-
hydrogen carbonate
HCO31-
mercury (I)
Hg22+
ACIDS
oxy-acids
acetic
CH3COOH
carbonic
H2CO3
nitric
HNO3
nitrous
HNO2
phosphoric
H3PO4
sulfuric
H2SO4
sulfurous
H2SO3
non-oxyacids
hydrochloric
HCl
hydrofluoric
HF
hydrobromic
HBr
hydroiodic
HI
hydrosulfuric
H2S
hydrocyanic
HCN
what is chemistry?
Author: asim /the structure and behaviour of atoms (elements)
the composition and properties of compounds
the reactions between substances with their accompanying energy exchange
the laws that unite these phenomena into a comprehensive system.
Chemistry is not an isolated discipline, for it merges into physics and biology. The origin of the term is obscure. Chemistry evolved from the medieval practice of alchemy. It's bases were laid by such men as Boyle, Lavoisier, Priestly, Berzelius, Avogadro, Dalton and Pasteur.
Branches Of Chemistry
Author: asim /This specific type of chemistry is concerned with elements containing carbon. Carbon is only the fourteenth most common element on earth, yet it creates the largest number of different compounds. This type of chemistry is important to the petrochemical, pharmaceutical, and textile industries. All living organisms contain at least some amount of carbon in their body. Inorganic Chemistry
This branch of chemistry deals with substances not containing carbon and that are not organic. Examples of such substances are minerals found in the earth's crust and non-living matter. There are many branches of inorganic chemistry. They include bioinorganic chemistry, nuclear science and energy, geochemistry, and synthetic inorganic chemistry, just to name a few. Physical Chemistry
This type of chemistry deals with the discovery and description of the theoretical basis of the behavior of chemical substances. This means also that it provides a basis for every bit of chemistry including organic, inorganic, and analytical. This chemistry is defined as dealing with the relations between the physical properties of substances and their chemical formations along with their changes. Biochemistry
Biochemistry is a science that is concerned with the composition and changes in the formation of living species. This type of chemistry utilizes the concepts of organic and physical chemistry to make the world of living organisms seem much clearer. Some people also consider biochemsitry as physiological chemistry and biological chemistry. The scientists that study biochemistry are called biochemists. They study such things as the properties of biological molecules, including proteins, lipids, carbohydrates, and nucleic acids. Other topics they focus on are the chemical regulation of metabolism, the chemistry of vitamins, and biological oxidation. Analytical Chemistry
This kind of chemistry deals mostly with the composition of substances.
All these branches of chemistry must deal with each other one way or another. If they didn't work in unison it would be impossible for these chemistries to perform the functions we need for experiments. For example you wouldn't be able measure the change of an organic substance without knowing how to use analytical chemistry.
Molecular Formula
Author: asim /Molecular mass
Author: asim /Molecular mass differs from more common measurements of the mass of chemicals, such as molar mass, by taking into account the isotopic composition of a molecule rather than the average isotopic distribution of many molecules. As a result molecular mass is a more precise number than molar mass; however it is more accurate to use molar mass on bulk samples. This means that molar mass is appropriate most of the time except when dealing with single molecules.
Atomic mass
Author: asim /Atomic number
Author: asim /The atomic number, Z, should not be confused with the mass number, A, which is the total number of protons and neutrons in the nucleus of an atom. The number of neutrons, N, is known as the neutron number of the atom; thus, A = Z + N. Since protons and neutrons have approximately the same mass (and the mass of the electrons is negligible for many purposes), the atomic mass of an atom is roughly equal to A.
Atoms having the same atomic number Z but different neutron number N, and hence different atomic masses, are known as isotopes. Most naturally occurring elements exist as a mixture of isotopes, and the average atomic mass of this mixture determines the element's atomic weight. The current standard for the atomic mass unit (amu), also termed the dalton (Da) is defined to be exactly 1/12th of the mass of a free (unbound) neutral 12C atom in its lowest-energy, or "ground" state.[1] In SI units, 1 Da = 1.660538782(83)×10−27 kg.
Discovery of the Neutron (1932)
Author: asim /Until 1932, the atom was known to consist of a positively charged nucleus surrounded by enough negatively charged electrons to make the atom electrically neutral. Most of the atom was empty space, with its mass concentrated in a tiny nucleus. The nucleus was thought to contain both protons and electrons because the proton (otherwise known as the hydrogen ion, H+) was the lightest known nucleus and because electrons were emitted by the nucleus in beta decay. In addition to the beta particles, certain radioactive nuclei emitted positively charged alpha particles and neutral gamma radiation. The symbols for these emissions are b - or –1e0, a 2+ or 24He2+, and 00g .
Twelve years earlier, Lord Ernest Rutherford, a pioneer in atomic structure, had postulated the existence of a neutral particle, with the approximate mass of a proton, that could result from the capture of an electron by a proton. This postulation stimulated a search for the particle. However, its electrical neutrality complicated the search because almost all experimental techniques of this period measured charged particles.
In 1928, a German physicist, Walter Bothe, and his student, Herbert Becker, took the initial step in the search. They bombarded beryllium with alpha particles emitted from polonium and found that it gave off a penetrating, electrically neutral radiation, which they interpreted to be high-energy gamma photons.
Discovery of Proton
Author: asim /The proton's mass and charge have both been determined. The mass is 1.673 × 10-24 g. The charge of a proton is positive, and is assigned a value of +1. The electron has a –1 charge, and is about 2,000 times lighter than a proton. In neutral atoms, the number of protons and electrons are equal.
The number of protons (also referred to as the atomic number) determines the chemical identity of an atom. Each element in the periodic table has a unique number of protons in its nucleus. The chemical behavior of individual elements largely depends, however, on the electrons in that element. Chemical reactions involve changes in the arrangements of electrons, not in the number of protons or neutrons.
The processes involving changes in the number of protons are referred to as nuclear reactions. In essence, a nuclear reaction is the transformation of one element into another. Certain elements—both natural and artificially made—are by their nature unstable, and spontaneously break down into lighter elements, releasing energy in the process. This process is referred to as radioactivity. Nuclear power is generated by just such a process.Read more: http://science.jrank.org/pages/5551/Proton-Discovery-properties.html#ixzz0J376HZXT&C
Discovery of Electron
Author: asim /Radioactive decay
Author: asim /The most common forms of radioactive decay are:[78][79]
Alpha decay is caused when the nucleus emits an alpha particle, which is a helium nucleus consisting of two protons and two neutrons. The result of the emission is a new element with a lower atomic number.
Beta decay is regulated by the weak force, and results from a transformation of a neutron into a proton, or a proton into a neutron. The first is accompanied by the emission of an electron and an antineutrino, while the second causes the emission of a positron and a neutrino. The electron or positron emissions are called beta particles. Beta decay either increases or decreases the atomic number of the nucleus by one.
Gamma decay results from a change in the energy level of the nucleus to a lower state, resulting in the emission of electromagnetic radiation. This can occur following the emission of an alpha or a beta particle from radioactive decay.
Electron cloud
Author: asim /Electrons, like other particles, have properties of both a particle and a wave. The electron cloud is a region inside the potential well where each electron forms a type of three-dimensional standing wave—a wave form that does not move relative to the nucleus. This behavior is defined by an atomic orbital, a mathematical function that characterises the probability that an electron will appear to be at a particular location when its position is measured.[55] Only a discrete (or quantized) set of these orbitals exist around the nucleus, as other possible wave patterns will rapidly decay into a more stable form.[56] Orbitals can have one or more ring or node structures, and they differ from each other in size, shape and orientation.[57]
Nucleus
Author: asim /mass spectrometer
Author: asim /Atom
Author: asim /chain reaction
Author: asim /2 (in physics) a reaction that perpetuates itself by the proliferating fission of nuclei and the release of atomic particles that cause more nuclear fissions.
Molecular Mass Calculations
Author: asim /Atomic mass carbon = 12.01 (from the Periodic Table) Atomic mass of oxygen = 16.00 (from the Periodic Table)
Molecular Mass (MM) for cabon monoxide = atomic mass carbon + atomic mass oxygen
Molecular mass (MM) = 12.01 + 16.00 = 28.01 g/mole
Formula Mass (Formula Weight)
Author: asim /Formula Mass (Formula Weight) is a more general term that can be applied to compounds that are not composed of molecules, such as ionic compounds.
In practice, the terms, molecular mass, molecular weight, formula mass and formula weight are used interchangeably by Chemists.
Formula Mass (Formula Weight)
Author: asim /Formula Mass (Formula Weight) is a more general term that can be applied to compounds that are not composed of molecules, such as ionic compounds.
In practice, the terms, molecular mass, molecular weight, formula mass and formula weight are used interchangeably by Chemists.
Molecular Mass (Molecular Weight)
Author: asim /In theory, the relative molecular mass or molecular weight of a compound is the mass of a molecule of the compound relative to the mass of a carbon atom taken as exactly 12.
In practice, the molecular mass, MM, (molecular weight, MW) of a compound is the sum of the atomic masses (atomic weights) of the atomic species as given in the molecular formula.
In theory we can only refer to the Molecular Mass or Molecular Weight of a covalent compound since only covalent compounds are composed of molecules.
Molecules of Compounds
Author: asim /A molecule of a compound consists of two or more atoms of different elements joined together in a fixed ratio.
Examples: CuSO4 contains Cu - 1 atom, S - 1 atom, O - 4 atoms
A chemical formula represents the composition of a molecule of the substance in terms of the symbol of the elements present in the molecule. It is also called molecular formula.
Microscale Gas Chemistry Experiments with Oxygen
Author: asim /AgCO3(s) Ag(s) + CO2(g) + O2(g)
On August 1, 1774 Joseph Priestley first prepared oxygen by directing the sun's light with a 12-inch diameter burning lens onto a sample of red mercurius calcinatus per se (now HgO). Thus, Priestley independently had discovered oxygen which he called dephlogisticated air. His explanation of the reaction using was:
mercurius calcinatus per se + heat yields quicksilver + dephlogisticated air
Today, we would describe the same reaction as follows:
HgO(s) Hg(l) + O2(g)
Uses of Carbon dioxide
Author: asim /History of human understanding
Author: asim /The properties of carbon dioxide were studied more thoroughly in the 1750s by the Scottish physician Joseph Black. He found that limestone (calcium carbonate) could be heated or treated with acids to yield a gas he called "fixed air." He observed that the fixed air was denser than air and did not support either flame or animal life. Black also found that when bubbled through an aqueous solution of lime (calcium hydroxide), it would precipitate calcium carbonate. He used this phenomenon to illustrate that carbon dioxide is produced by animal respiration and microbial fermentation. In 1772, English chemist Joseph Priestley published a paper entitled Impregnating Water with Fixed Air in which he described a process of dripping sulfuric acid (or oil of vitriol as Priestley knew it) on chalk in order to produce carbon dioxide, and forcing the gas to dissolve by agitating a bowl of water in contact with the gas.[7]
Carbon dioxide was first liquefied (at elevated pressures) in 1823 by Humphry Davy and Michael Faraday.[8] The earliest description of solid carbon dioxide was given by Charles Thilorier, who in 1834 opened a pressurized container of liquid carbon dioxide, only to find that the cooling produced by the rapid evaporation of the liquid yielded a "snow" of solid CO2.[9]
Properties of carbon dioxide
Author: asim /There are several physical and chemical properties, which belong to carbon dioxide.Here we will sum them up in a table.
Property
Value
Molecular weight
44.01
Specific gravity
1.53 at 21 oC
Critical density
468 kg/m3
Concentration in air
370,3 * 107 ppm
Stability
High
Liquid
Pressure < 415.8 kPa
Solid
Temperature < -78 oC
Henry constant for solubility
298.15 mol/ kg * bar
Water solubility
0.9 vol/vol at 20 oC
What is carbon dioxide and how is it discovered?
Author: asim /Energy - Absorbed or Released
Author: asim /Chemical Changes
Author: asim /Matter is never destroyed or created in chemical reactions. The particles of one substance are rearranged to form a new substance. The same number of particles that exist before the reaction exist after the reaction.
Chemical vs Physical Change
Author: asim /Atoms Around Us
Author: asim /The List of Elements
Author: asim /We've got 18 to choose from. From the launch of the site we've been asked, "Why start with 18?" The rules for the first 18 elements are very straight-forward. (1) Electrons fit nicely into three shells.(2) These elements make up most of the matter in the universe.(3) It's a lot easier to remember facts about 18 elements than over 100 elements.
Element 1: HydrogenElement 2: HeliumElement 3: LithiumElement 4: BerylliumElement 5: BoronElement 6: CarbonElement 7: NitrogenElement 8: OxygenElement 9: Fluorine
Element 10: NeonElement 11: SodiumElement 12: MagnesiumElement 13: AluminumElement 14: SiliconElement 15: PhosphorusElement 16: SulfurElement 17: ChlorineElement 18: ArgonWho are we kidding? We teased you with only 18 elements for many years. We've added the next 18 elements from the fourth period. You need to remember that this is the first row with transition elements. Those transition metals have electron configurations that are a little different from the first 18. Make sure you understand the first 18 before you move on to this set.
Element 19: PotassiumElement 20: CalciumElement 21: ScandiumElement 22: TitaniumElement 23: VanadiumElement 24: ChromiumElement 25: ManganeseElement 26: IronElement 27: Cobalt
Element 28: NickelElement 29: CopperElement 30: ZincElement 31: GaliumElement 32: GermaniumElement 33: ArsenicElement 34: SeleniumElement 35: BromineElement 36: Krypton
The Same Everywhere
Author: asim /Periodic Table and the Elements
Author: asim /Changing States of Matter
Author: asim /Matter is the Stuff Around You
Author: asim /Chemical Reactions
Author: asim /Key Points1. A chemical change must occur. You start with one compound and turn it into another. That's an example of a chemical change. A steel garbage can rusting is a chemical reaction. That rusting happens because the iron (Fe) in the metal combines with oxygen (O2) in the atmosphere. When a refrigerator or air conditioner cools the air, there is no reaction. That change in temperature is a physical change. Nevertheless, a chemical reaction can happen inside of the air conditioner. 2. A reaction could include ions, molecules, or pure atoms. We said molecules in the previous paragraph, but a reaction can happen with anything, just as long as a chemical change occurs (not a physical one). If you put pure hydrogen gas (H2) and pure oxygen gas in a room, they can be involved in a reaction. The slow rate of reaction will have the atoms bonding to form water very slowly. If you were to add a spark, those gases would create a reaction that would result in a huge explosion. Chemists would call that spark a catalyst. 3. Single reactions often happen as part of a larger series of reactions. Take something as simple as moving your arm. The contraction of that muscle requires sugars for energy. Those sugars need to be metabolized. You'll find that proteins need to move in a certain way to make the muscle contract. A whole series (hundreds actually) of different reactions are needed to make that simple movement happen.