About Electrochemistry??????

Different atoms pull on bonding electrons to differing degrees, and this difference is the pivotal property in determining whether a covalent or ionic bond is formed. When one atom has a much higher pull on bonding electrons than its partner, electron transfer occurs, and an ionic compound is formed. When both atoms have similar attractions for the bonding electrons, they'll share them more equitably and a covalent compound is formed.

Elements can be ranked by their relative attraction for bonding electrons. The more different their ranks, the more likely the bond is to be ionic.

Elements by their ability to attract bonding electrons - Linus Pauling and others considered several elemental properties to develop a consistent ranking scheme. Pauling used the element's ionization energy and electron affinity to predict how it will behave in a bond. The more energy it takes to pull off the outer electron of an atom, he reasoned, the less likely it is to allow another atom to take those electrons. The more energy the atom releases when it gains an electron, the more likely it is to take electrons from another atom in bonding. These two energies were used to compute a numerical score called anelectronegativity. Electronegativity ranks the element's tendency to attract electrons and acquire a more negative charge in a bonding situation. 

Electronegativity will increase going left to right across the periodic table. Fluorine's high nuclear charge coupled with its small size make it hold onto bonding electrons more tightly than any other element. Lithium has a lower nuclear charge and is actually larger than fluorine. Its valence electron is not tightly held and it tends to surrender it in chemical bonds.

How are electronegativity values used? Consider coupling two fluorine atoms together. Even though each atom has a high attraction for bonding electrons, both attract them equally. The electronegativity difference between the atoms is zero, and the bond ispure covalent. 

Oxidation Number of Xenon

Oxidation Numbers and Position in the Periodic Table

Compounds of xenon are by far the most numerous of the rare-gas compounds.

With the exception of XePtF₆, rare-gas compounds have oxidation numbers of +2, +4, +6, and +8,  as shown by the examples cited in the table below.

Compounds of Xenon and their Oxidation Numbers

Compound		Oxidation Number			Compound		Oxidation Number
XeF+		+2			XeO3		+6
XeF2		+2			XeOF4		+6
Xe2F3+		+2			XeO2F2		+6
XeF3+		+4			XeO3F-		+6
XeF4		+4			XeO4		+8
XeOF2		+4			XeO64-		+8
XeF5+		+6			XeO3F2		+8
XeF6		+6			XeO2F4		+8
Xe2F11+		+6			XeOF5+		+8

What is Noble Gas????

Discovery of Noble Gases

In 1892 Lord Rayleigh found that oxygen was always 15.882 times more dense than hydrogen, no matter how it was prepared.

When he tried to extend this work to nitrogen, he found that nitrogen isolated from air was denser than nitrogen prepared from ammonia.

William Ramsey attacked this problem by purifying a sample of nitrogen gas to remove any moisture, carbon dioxide, and organic contaminants.

He then passed the purified gas over hot magnesium metal, which reacts with nitrogen to form the nitride.

3 Mg(s)

+

N2(s)

Mg3N2(s)

When he was finished, Ramsey was left with a small residue of gas that occupied roughly 1/80th of the original volume.

He excited this gas in an electric discharge tube and found that the resulting emission spectrum contained lines that differed from those of all known gases.

After repeated discussions of the results of these experiments, Rayleigh and Ramsey jointly announced the discovery of a new element, which they named argon from the Greek word meaning the "lazy one" because this gas refused to react with any element or compound they tested.

Argon did not fit into any of the known families of elements in the periodic table, but its atomic weight suggested that it might belong to a new group that could be inserted between chlorine and potassium.

Shortly after reporting the discovery of argon in 1894, Ramsey found another unreactive gas when he heated a mineral of uranium.

The lines in the spectrum of this gas also occurred in the spectrum of the sun, which led Ramsey to name the element helium (from the Greek helios, "sun").

Experiments with liquid air led Ramsey to a third gas, which he named krypton ("the hidden one").

Experiments with liquid argon led him to a fourth gas, neon ("the new one"), and finally a fifth gas,xenon ("the stranger").

These elements were discovered between 1894 and 1898. Because Moissan had only recently isolated fluorine for the first time and fluorine was the most active of the known elements.

Ramsey sent a sample of argon to Moissan to see whether it would react with fluorine. It did not.

The failure of Moissan's attempts to react argon with fluorine, coupled with repeated failures by other chemists to get the more abundant of these gases to undergo chemical reaction, eventually led to their being labeled inert gases.

The development of the electronic theory of atoms did little to dispel this notion because it was obvious that these gases had very symmetrical electron configurations.

As a result, these elements were labeled "inert gases" in almost every text book and periodic table until about 30 years ago.

In 1962 Neil Bartlett found that PtF₆ was a strong enough oxidizing agent to remove an electron from an O₂ molecule.

PtF6(g)	+	O2(g)		[O2+][PtF6-](s)

Bartlett realized that the first ionization energy of Xe (1170 kJ/mol) was slightly smaller than the first ionization energy of the O₂ molecule (1177 kJ/mol).

He therefore predicted that PtF₆ might also react with Xe. When he ran the reaction, he isolated the first compound of a Group VIIIA element.

Xe(g)	+	PtF6(g)		[Xe+][PtF6-](s)

A few months later, workers at the Argonne National Laboratory near Chicago found that Xe reacts with F₂ to form XeF₄.

Since that time, more than 200 compounds of Kr, Xe, and Rn have been isolated.

No compounds of the more abundant elements in this group (He, Ne, and Ar) have yet been isolated.

However, the fact that elements in this family can undergo chemical reactions has led to the use of the term rare gases rather than inert gases to describe these elements. 

Artifact

Introduce Acids and Base
Have with Acids and Base

Me and SKP6024

ICT IN CHEMISTRY EDUCATION & MYSELF

MY 1^st impression of this Course????

The first impression when i heard and overview what is all about this course, really made me nervous and I thought it take a long take to make all the assignments. I just thought am i can go through all this for one semester. First time in this class, the beauty lady appears and introduced her as CIK HAJAH ASMAYATI..She is so kind and very friendly and also all the friends in this course very friendly of each other. I cannot wait for the next class to see my colleague and CIK ASMAYATI.....

Second meeting we need to create our own blog..Argghh..actually i never had blog before because i'm not very addicted to tell story or sharing thing other especially about personal and activities that i do everyday..but CIK ASMAYATI persuade us to create for our portfolio for this subject..BY HOOK OR BY CROOK i need to create one for me...lalala...Whatever it is,i get a good friends who can refer when i had difficult situation...thank you YOU ALL and CIK ASMAYATI..!!! Luv u alll....muahhh

Selamat Hari Guru 2012: Guru inovatif Melonjakkan Transformasi Pendidikan Negara

Guru Inovatif Melonjakkan Transformasi Pendidikan Negara

Kita berbicara tentang inovasi

Ciptaan baharu gaya hidup kini

Meningkatkan Produktiviti Terkini

Bangun, beranikan terima seruan

Mendidik, memimpin penuh berwawasan

Menciptakan kreativiti

Melahirkan Guru Inovatif

c/o

Sahutlah cabaran, perubahan

Daulatkan Bidang Pendidikan,

Guru Inovatif Melonjakkan

Transformasi Pendidikan Negara

Malaysia Ku tercinta

Kita berbicara tentang inovasi

Ciptaan baharu gaya hidup kini

Meningkatkan Produktiviti Terkini

Tiada pernah jemu tiada putus asa

Sedia menimba ilmu di mana saja

Binakanlah keyakinan

Merentasi segala halangan