"If you're not part of the solution, you're part of the precipitate.  ~Henry J. Tillman"

Chemistry isn't as boring as it may seem,here we will provide you enough erudition along the way and make you experience a pleasurable way of tutorials about chemistry.Not your typical tutorial site >:)

See for yourself.

-- @kimmontealto & @franzsantos

http://kimemvee.blogspot.com/

http://lamentations-of-chemistry.blogspot.com/

Candle Making 101 Tomorrow :D

Chemistry Jokes :))

Let’s Speak Chemistry!

"I think your website is beryllium!" (read as brilliant)

"That's a pro-phosphorous idea!" (read as preposterous)

"I can't be arsenic-ed!" (read as arsed)

"This is so boron!" (read as boring)

"Pick it up off the fluor-ine!" (read as floor)

"Lith-ium alone!" (read as leave him)

"This is a-bismuth!" (read as abysmal)

"I've got a bad gold" (read as cold)

"Is she Indium?" (read as Indian)

"Did he have a car-bon?" (read as car bomb)

"Pass the lattice" (read as lettuce)

"Would you like a polo-nium t?" (read as polo mint)

"Can you iron my shirt please?" (read as iron)

"I can't bar-ium" (read as bare him)

"Can they cur-ium?" (read as cure him)

"Caes-ium!" (read as caese him)

"That was so-dium good" (read as so damn)

“How many have we done sul-phur?” (read as so far)

"Keep your i-on the ball" (read as eye on)

"A friend of mine pierced his tung-sten" (read as tongue)

"A-cid that one" (read as I said)

"A-mine the other one" (read as I mean)

"You're too easily lead" (read as lead)

Julian: "My trousers keep falling down!"

Nick: "This man-ga-nese a belt!" (read as man needs)

Nick: "We need to get so many things for our cat"

Julian: "I don't think we'll be able to remember them all"

Nick: "Well then we will have to make the cat-a-lyst!"

”I zinc we are done because all the other jokes ar-gon!”

Chemistry Pride

January 5^th marks the passing of Harold Urey. Urey was an American chemist who was awarded the 1934 Nobel Prize in Chemistry for his discovery of deuterium.

Deuterium is an isotope of hydrogen. The most common form of hydrogen has one proton and no neutrons, but deuterium contains a proton and neutron in its nucleus. This isotope has the same chemical properties as hydrogen and can combine with oxygen to create water. Deuterium water is also known as 'heavy water'. Heavy water is used in many applications such as nuclear magnetic resonance, neutron moderation in nuclear power plants and organic chemistry.

Urey discovered deuterium by investigations of heavy water in 1931 and was important in the understanding of the concepts of isotopes.

Harold Clayton Urey was born in Walkerton, Indiana, on April 29, 1893, as the son of the Rev. Samuel Clayton Urey and Cora Rebecca Reinoehl, and grandson of pioneers who settled in Indiana. His early education in rural schools led to his graduation from high school in 1911 after which he taught for three years in country schools. In 1914 he entered the University of Montana and received his Bachelor of Science degree in Zoology in 1917. He spent two years as a research chemist in industry before returning to Montana as an instructor in Chemistry. In 1921 he entered the University of California to work under Professor Lewis and he was awarded the degree of Ph.D. in Chemistry in 1923. He spent the following year in Copenhagen at Professor Niels Bohr's Institute for Theoretical Physics as American-Scandinavian Foundation Fellow to Denmark and on his return to the United States he became an Associate in Chemistry at Johns Hopkins University. In 1929 he was appointed Associate Professor in Chemistry at Columbia University and he became Professor in 1934; during the period 1940-1945 he was also Director of War Research, Atomic Bomb Project, Columbia University. He moved to the Institute for Nuclear Studies, University of Chicago in 1945 as Distinguished Service Professor of Chemistry and became Martin A. Ryerson Professor in 1952. He was George Eastman Visiting Professor, University of Oxford, during 1956-1957 and in 1958 he took his present post as Professor-at-Large, University of California.

Professor's Urey's early researches concerned the entropy of diatomic gases and problems of atomic structure, absorption spectra and the structure of molecules. In 1931 he devised a method for the concentration of any possible heavy hydrogen isotopes by the fractional distillation of liquid hydrogen: this led to the discovery of deuterium. Together with the late Dr. E.W. Washburn, he evolved the electrolytic method for the separation of hydrogen isotopes and he carried out thorough investigations of their properties, in particular the vapour pressure of hydrogen and deuterium, and the equilibrium constants of exchange reactions. He later worked on the separation of uranium isotopes and, more recently, he has been concerned with the measurement of paleotemperatures, investigations into the origin of the planets, and the chemical problems of the origin of the earth.

He is the author of the books Atoms, Molecules and Quanta (1930, with A.E. Ruark), and The Planets (1952). He was editor of the Journal of Chemical Physics during 1933-1940 and he has written numerous papers on the structure of atoms and molecules, the discovery of heavy hydrogen and its properties, separation of isotopes, measurement of paleotemperatures and the origin of planets. These have been published in many different chemical journals.

Professor Urey received the Willard Gibbs Medal (American Chemical Society) in 1934; Davy Medal (Royal Society, London), 1940; Franklin Medal, 1943; Medal for Merit, 1946; Cordoza Award, 1954; Honor Scroll Award (American Institute of Chemists), 1954; Joseph Priestley Award, 1955; Alexander Hamilton Award, 1961; and the J. Lawrence Smith Award (National Academy of Sciences), 1962. He has received honorary Doctor of Science degrees of Montana, Princeton, Newark, Columbia, Oxford, Washington and Lee, McMaster, Yale, Indiana, Birmingham Universities, and of the Universities of Athens, Durham, and Saskatchewan; also honorary Doctor of Law degree from Wayne University and the University of California. He is a member of many of the more important scientific societies of the world, and is Honorary Fellow of the Chemical Society (London), the National Institute of Sciences of India and the Weizmann Institute of Science (Israel).

In 1926 he married Frieda Daum. They have three daughters and one son.

Balancing Chemical Equation

What is a balanced equation?

A chemical equation is balanced when the number of atoms of each type on each side of the equation is the same. Which means if you have 12 hydrogens on the left hand side of the equation, you must have 12 hydrogens on the right hand side, if there are 4 oxygens on the left, there must 4 oxygens on the right, and so on. This is because of the law of conservation of mass - you can't make or destroy atoms during a chemical reaction. But you can't just add atoms at random to each side, you have to work with the molecules of the reactants. Also, you will find it very tricky to try to balance a word equation, it is very much easier to use a chemical equation with chemical symbols, as then you will be able to see how many atoms of each type are in each chemical.

Example 1
Unbalanced Equation:- C₃H₈ + O₂ ---> H₂O + CO₂

There are three carbons on the left, but only one on the right.
There are eight hydrogens on the left but only two on the right.
There are two oxygens on the left but three on the right.
Balanced Equation:- C₃H₈ + 5O₂ ---> 4H₂O + 3CO₂

How do we balance the equation?

Balancing chemical equations isn't difficult, once you know the way to do it. Start by finding out how many atoms of each type are on each side of the equation. Some teachers recommend making a little table listing the numbers of each atom for the left hand side and for the right hand side.


Next, look for an element which is in only one chemical on the left and in only one on the right of the equation. (But it is usually a good idea to leave hydrogen and oxygen until you've done the others first.)
To balance that element, multiply the chemical species on the side which doesn't have enough atoms of that type by the number required to bring it up to the same as the other side. The number is called the coefficient.

BUT
If you have to multiply by, say, 2 1/2, do so, THEN multiply EVERYTHING on each side of the equation by two to get rid of the half.

We don't like having halves in equations, as you can't get half a molecule.
Now look for the next element or species that is not balanced and do the same thing.
Repeat until you are forced to balance the hydrogen and oxygens.
If there is a complex ion, sometimes called a polyatomic ion, on each side of the equation that has remained intact, then that can often be balanced first, as it is acts as a single species. The ions NO₃^- and CO₃^2- are examples of a complex ion.


A VERY useful rule is to leave balancing oxygen and hydrogen to the last steps as these elements are often in more than one chemical on each side , and it is not always easy to know where to start. Some people also say you should leave any atom or species with a valancy of one one until the end, and also generally leave anything present as an element to the end.


In Example 1 above, you would balance the carbons first, by putting a 3 in front of the CO₂, then balance the hydrogens by putting a 4 in front of H₂O and finally the oxygens (which are in more than one compound on the right, so we leave them until last) by putting a 5 in front of the O₂.

Example 2
Unbalanced equation:- H₂SO₄ + Fe ---> Fe₂(SO₄)₃ + H₂

Balance the SO₄ first (as it is a complex ion and it is in one chemcial species on each side)
3H₂SO₄ + Fe ---> Fe₂(SO₄)₃ + H₂
Now balance the Fe (which is also in one chemical on each side)
3H₂SO₄ + 2Fe ---> Fe₂(SO₄)₃ + H₂
Finally, balance the hydrogen (although it is in one chemical species on each side, it is usually a good idea to leave it until last)
Balanced Equation:- 3H₂SO₄ + 2Fe ---> Fe₂(SO₄)₃ + 3H₂


We alter the coeficients in the equation.
Do NOT touch the subscripts for the atoms in a chemical species, or you will change it into an different chemical. That would be a bit like saying I want six chicken legs for a meal, so I'll go get a six-legged chicken. As chickens have two legs, you will need three normal, two-legged, chickens, not a six-legged mutant monster, probably from outer space.
If you start by trying to balance something which is in more than one species on one side, you can't easily tell which species you should have more of, and so can end up going round in circles, continually altering things. If this happens, just start again, but balancing atoms or complex ions that are in one species on each side. (This is important or it will not work.)


EVALUATION:

Question Excerpt From Balancing Chemical Equations

1. 1.     ______NH3             -->           ______N2             +            ______H2
2. 1.     ______ H2S             +            ______ O2          -->             ______ H2O          +         ______ S
3. What would happen if we did not follow the law of conservation of mass when taking apart and then putting together a car for repair?
4. ___ CH4 + ___O2 --> ___CO2 + ___H2O
5. 1.     ______ C            +             ______ O2             -->            ______ CO2 write the correct prefixes below
6. What law says we need to have balanced chemical equations?
7. ______ CH­2O            +             ______ HCl             -->            ______ CH4O             +            ______ Cl2

Rate Law

Rate Law

We will begin this discussion with a general description of reactions, rates and rate laws. We will discuss a general reaction

                              (1)

As the reaction occurs, concentrations of reactants and products will change. The rate of the reaction can be characterized by any of the following.

                              (2)

The above equation defines the rate of reaction. The rate of reaction is defined in terms of the rate of change of concentration for any component of the reaction, divided by the stochiometric coefficient for that component. Stochiometric coefficients are positive for products and negative for reactants.
The rate of a reaction is dependent on the concentrations of chemical species involved in the reaction. In general the rate of a reaction depends on the concentrations of species as follows:

rate = k [A]^p [B]^q                                                                (3)
This equation is the rate law for the reaction. The proportionality constant, k, is known as the rate constant for the reaction. In general, the rate constant depends on temperature, commonly increasing with temperature. The exponents in the rate law are often small integers (positive or negative) or simple fractions. These exponents are determined experimentally.

Reaction Order

The exponent on the concentration terms in equation (3) is the order of the reaction with respect to each component of the reaction. For example, p is the order of the reaction with respect to the concentration of component A. If p is zero, the rate of reaction is independent of the concentration of A. The sum of the exponents is the overall order of the reaction.
Initial Rate Method:
By measuring the change in concentration with time of one of the components of the reaction system, one can collect rate information. This data can be used to determine the initial rate of the reaction, the rate early in the reaction. By taking the ln of equation (3),

ln(rate) = ln k + p ln[A] +q ln[B]                         (4)

one gets an expression relating the ln of the rate to the sum of the ln of the rate constant and the ln of the concentrations of the reaction components. The ln of the concentrations of the individual reaction components are multiplied by the reaction order for that component. By measuring the initial rate of the reaction while changing the initial concentration of one of the reaction components, one can determine the order of the reaction with respect to that component. This is done by plotting the ln of the initial reaction rate versus the ln of the initial concentration of the varying component (all other initial concentrations are held constant). This should result in a straight line of slope equal to the order for that component. This process can be repeated, varying concentrations of other individual components in the reaction system.

demo videos
EVALUATION:
http://www.chem.ufl.edu/~itl/2041_f97/kinetics_quiz.html

Chemical Bonding

Though the periodic table has only 118 or so elements, there are obviously more substances in nature than 118 pure elements. This is because atomscan react with one another to form new substances called compounds (see our Chemical Reactions module). Formed when two or more atoms chemically bond together, the resulting compound is unique both chemically and physically from its parent atoms.

Let's look at an example.  The element sodium is a silver-colored metal that reacts so violently with water that flames are produced when sodium gets wet.  The element chlorine is a greenish-colored gas that is so poisonous that it was used as a weapon in World War I.  When chemically bonded together, these two dangerous substances form the compound sodium chloride, a compound so safe that we eat it every day - common table salt!

enlarge image

In 1916, the American chemist Gilbert Newton Lewis proposed that chemical bonds are formed between atoms because electrons from the atoms interact with each other. Lewis had observed that many elements are most stable when they contain eight electrons in their valence shell. He suggested that atoms with fewer than eight valence electrons bond together to share electrons and complete their valence shells.

While some of Lewis' predictions have since been proven incorrect (he suggested that electrons occupy cube-shaped orbitals), his workestablished the basis of what is known today about chemical bonding. We now know that there are two main types of chemical bonding; ionic bonding and covalent bonding.

Ionic bonding

In ionic bonding, electrons are completely transferred from one atom to another. In the process of either losing or gaining negatively charged electrons, the reacting atoms form ions. The oppositely charged ions are attracted to each other by electrostatic forces, which are the basis of theionic bond.

For example, during the reaction of sodium with chlorine:

sodium (on the left) loses its one valence electron to chlorine (on the right),

resulting in

a positively charged sodium ion(left) and a negatively charged chlorine ion (right).

The reaction of sodium with chlorine

Concept simulation - Reenacts the reaction of sodium with chlorine.

(Flash required)

Notice that when sodium loses its one valence electron it gets smaller in size, while chlorine grows larger when it gains an additional valence electron. This is typical of the relative sizes of ions to atoms. Positive ions tend to be smaller than their parent atoms while negative ions tend to be larger than their parent. After the reaction takes place, the charged Na⁺and Cl^- ions are held together by electrostatic forces, thus forming an ionic bond. Ionic compounds share many features in common:

• Ionic bonds form between metals and nonmetals.
• In naming simple ionic compounds, the metal is always first, the nonmetal second (e.g., sodium chloride).
• Ionic compounds dissolve easily in water and other polar solvents.
• In solution, ionic compounds easily conduct electricity.
• Ionic compounds tend to form crystalline solids with high melting temperatures.

This last feature, the fact that ionic compounds are solids, results from the intermolecular forces (forces between molecules) in ionic solids. If we consider a solid crystal of sodium chloride, the solid is made up of many positively charged sodium ions (pictured below as small gray spheres) and an equal number of negatively charged chlorine ions (green spheres). Due to the interaction of the charged ions, the sodium and chlorine ions are arranged in an alternating fashion as demonstrated in the schematic. Each sodium ion is attracted equally to all of its neighboring chlorine ions, and likewise for the chlorine to sodium attraction. The concept of a singlemolecule does not apply to ionic crystals because the solid exists as one continuous system. Ionic solids form crystals with high melting points because of the strong forces between neighboring ions.

	Cl-1 Na+1 Cl-1 Na+1 Cl-1 Na+1 Cl-1 Na+1 Cl-1 Na+1 Cl-1 Na+1 Cl-1 Na+1 Cl-1 Na+1 Cl-1 Na+1 Cl-1 Na+1
Sodium Chloride Crystal	NaCl Crystal Schematic

Covalent bonding

The second major type of atomic bonding occurs when atoms shareelectrons. As opposed to ionic bonding in which a complete transfer of electrons occurs, covalent bonding occurs when two (or more) elementsshare electrons. Covalent bonding occurs because the atoms in thecompound have a similar tendency for electrons (generally to gain electrons). This most commonly occurs when two nonmetals bond together. Because both of the nonmetals will want to gain electrons, the elements involved will share electrons in an effort to fill their valence shells. A good example of a covalent bond is that which occurs between two hydrogen atoms. Atoms of hydrogen (H) have one valence electron in their firstelectron shell. Since the capacity of this shell is two electrons, each hydrogen atom will "want" to pick up a second electron. In an effort to pick up a second electron, hydrogen atoms will react with nearby hydrogen (H) atoms to form the compound H₂. Because the hydrogen compound is a combination of equally matched atoms, the atoms will share each other's single electron, forming one covalent bond. In this way, both atoms share the stability of a full valence shell.

Covalent bonding between hydrogen atoms

Concept simulation - Recreates covalent bonding between hydrogen atoms.

(Flash required)

Unlike ionic compounds, covalent molecules exist as true molecules. Becauseelectrons are shared in covalent molecules, no full ionic charges are formed.  Thus covalent molecules are not  strongly attracted to one another.  As a result, covalent molecules move about freely and tend to exist as liquids or gases at room temperature.  

Multiple Bonds: For every pair of electrons shared between two atoms, a single covalent bond is formed.  Some atoms can share multiple pairs of electrons, forming multiple covalent bonds.  For example, oxygen (which has six valence electrons) needs two electrons to complete its valence shell.  When two oxygen atoms form the compound O₂, they share two pairs of electrons, forming two covalent bonds.  

Lewis Dot Structures: Lewis dot structures are a shorthand to represent the valence electrons of an atom. The structures are written as theelement symbol surrounded by dots that represent the valence electrons. The Lewis structures for the elements in the first two periods of the periodic table are shown below.

	Lewis Dot Structures

Lewis structures can also be used to show bonding between atoms. The bonding electrons are placed between the atoms and can be represented by a pair of dots or a dash (each dash represents one pair of electrons, or one bond). Lewis structures for H₂ and O₂ are shown below.

H2	H:H	or	H-H
O2

Polar and nonpolar covalent bonding

There are, in fact, two subtypes of covalent bonds. The H₂ molecule is a good example of the first type of covalent bond, the nonpolar bond. Because both atoms in the H₂ molecule have an equal attraction (or affinity) for electrons, the bonding electrons are equally shared by the two atoms, and a nonpolar covalent bond is formed. Whenever two atoms of the same element bond together, a nonpolar bond is formed.

A polar bond is formed when electrons are unequally shared between twoatoms. Polar covalent bonding occurs because one atom has a stronger affinity for electrons than the other (yet not enough to pull the electrons away completely and form an ion). In a polar covalent bond, the bonding electrons will spend a greater amount of time around the atom that has the stronger affinity for electrons. A good example of a polar covalent bond is the hydrogen-oxygen bond in the water molecule.

H2O: a water molecule

Water molecules contain two hydrogen atoms(pictured in red) bonded to one oxygen atom (blue). Oxygen, with six valence electrons, needs two additional electrons to complete its valence shell. Each hydrogen contains one electron. Thus oxygen shares the electrons from two hydrogen atoms to complete its own valence shell, and in return shares two of its own electrons with each hydrogen, completing the H valence shells.

Polar covalent bonding simulated in water

The primary difference between the H-O bond in water and the H-H bond is the degree of electron sharing. The large oxygen atom has a stronger affinity for electrons than the small hydrogen atoms. Because oxygen has a stronger pull on the bonding electrons, it preoccupies their time, and this leads to unequal sharing and the formation of a polar covalent bond.  

The dipole

Because the valence electrons in the water molecule spend more time around the oxygen atom than the hydrogen atoms, the oxygen end of the molecule develops a partial negative charge (because of the negative charge on the electrons). For the same reason, the hydrogen end of the molecule develops a partial positive charge. Ions are not formed; however, the molecule develops a partial electrical charge across it called a dipole. The water dipole is represented by the arrow in the pop-up animation (above) in which the head of the arrow points toward the electron dense (negative) end of the dipole and the cross resides near the electron poor (positive) end of the molecule

VIDEOS
EVALUATION:
http://chemistry.about.com/library/weekly/blbondsquiz.htm