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Wednesday, 14 January 2015

Hydrogen

hyderogen

Hydrogen occupies the first place in the periodic classification of Mendeleev. Hydrogen is an atom consists of a single proton around which revolves a single electron. Its atomic weight is 1, 00797.

Physical Properties

Hydrogen is an odorless, colorless gas. It is the lightest of all the substances. its density in air is 0.07.

The hydrogen is after the helium gas more difficult to liquefy. Its critical temperature of 240 ºC, its boiling point at atmospheric pressure is 252.7 ºC, solidifies at 259.2 ºC. It is a fair conductor of heat and electricity.

The hydrogen molecule is diatomic, at room temperature these molecules are stable isomers, called ortho hydrogen and Para hydrogen.

Chemical Properties

2 molecule of methane

Generally active little cold, hydrogen gives rise, in hot or in the presence of catalysts, in numerous reactions. Has oxidation number 1, so it is mono valiant. It combines directly to most non-metals and alkali metals and alkaline earth metals. The speed of the reaction and decrease the amount of heat carried by fluorine to iodine

The combination with the oxygen to give water is often the case with explosion at elevated temperature or in the presence of a catalyst (platinum sponge). Combines with sulfur to 250 ºC; the reaction with nitrogen, which gives rise to ammonia, requires the use of catalysts, high temperatures and high pressures. Reacts with the carbon to 1,100 ° C to generate methane; when operating electric arc is obtained instead acetylene 

Robert Boyle

Robert-Boyle

(1627/01/25 to 1691/12/30)

He was Irish Mathematician and scientist, He was born on January 25, 1627 in Lismore, Ireland. He belonged to the Royal Society.

He started his Education at Eton in 1835. Later he traveled throughout Europe. In 1656 he lived in Oxford where he collaborated with Robert Hooke.

He made important contributions to physics and chemistry, but he is famous for Boyle's law. In that law Robert Boyle described the ideal gas. This law was published in the appendix of his written work in 1661.

He was the first to use the term "Chemical Analysis" in its present meaning.
It is well known the law: "At temperatures equal volumes of gases are inversely proportional to the pressure." In his book Sceptical Chemist (1661).

He believes that matter was composed of corpuscles which were built differently on different configurations of primary particles.

Robert Boyle died on December 30, 1691 in London.

Projectile Motion

Projectile

An object on which the one and only force acting on object is gravity is called projectile.

Example

Object dropped downward from the rest the motion of object is called projectile, (the air resistance is negligible).

An object thrown upward from rest the motion of object is called projectile (the air resistance is negligible). And an object which is thrown upward at horizontal angle the motion of object is also called projectile (the air resistance is negligible).

According to the law, a projectile is a single force that acts upon an object (the force of gravity). If there were other force acting on an object, then the object would not be a projectile.
Thus, a projectile is any object upon which the only force is gravity.

Types And Forms of Communication

types-and-forms-of-communication
TYPES OF COMMUNICATION


I) Verbal communication:

This form of communication means that is being communicated in writing or orally. Use is made of spoken or written language
.
Written communication is cheaper when there is a large group of people needs to be addressed.
Verbal communication is used faster during a one on one conversation.

II) Non-verbal communication:
This type of communication means that is communicated without speaking. For example through posture, eye contact and gestures people make or body language.

Non-verbal communication can be divided into two parts namely:
Conscious non-verbal and non-intentional communication

III) Vocal communication
Vocal Communication means that all forms of communication to be made by the use of the voice.

IV) Non-vocal communication
Non-vocal communication is communication with touch, taste and smell, and even body language.


FORMS OF COMMUNICATION

There are five forms of communication.

I) Information: 
General communication. For example, how the bus departs.

II) Information: 
Conscious data communications. For example communication about what should be done if an accident happened.

III) Public relations:
communication between an organization and its publics.

IV) Advertising:
Communication with the aim of strengthening a brand. Remember the commercials Anderson. They buy a piece of airtime so that their shampoo is purchased.

V) Propaganda:
Communication aimed at conveying ideas. The objective is to convince people. Think of the political parties have to convince everyone the purpose of their ideal.

The Noble Gases

Noble-gases

The elements of group VIII A (also known as group O) are known as noble gases,
Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe) and rarely Radon (Rn) are the elements of group VIII A.

They are all monoatomic gases. These gases are colorless, tasteless and odorless, and distinguished from all other elements, for their high chemical stability. 

This is due to their electronic configuration, with the exception of helium, split eight electrons in the outer layer (octet). All noble gases are present in the atmosphere in trace amounts, except argon, whose percentage by volume exceeds 0.9%. 

They are obtained as byproducts in the extraction of nitrogen and oxygen from the liquid.


Characteristics of Noble Gases (GROUP VIII A)


Names helium  Neon Argon  Krypton  Xenon  Radon

Symbol He  Ne Ar Kr Xe Rn

Atomic number 2   10   18 36 54  86

Electron configuration 1s2 2s22p6 3s23p6   4s24p6  5s25p6  6s26p6

Melting point (° C) -272  -249  -189  -157  -112 -110

Boiling point (° C) -269  -246  -186  -153  -107  -62

History of Atom

History-of-atom

John Dalton was the 1st scientist he gave the idea of the atom as being the building block or smallest unit. Since the introduction of this theory, the huge number of scientists followed that and came out, with the thought of existing tiny particles. Afterward, with the development of new scientific tricks, it was proved by the John Dalton in the 19th century.

He took a long time to prove his theory.

Dalton developed the idea of the atom, but he had no sure idea that what role it played in nature or in another object. It has general idea, was that the atom is the smallest part of any matter.

+ve and -ve charged electrons

Many scientists, along to geographical distance, worked on those theories about the smaller particles, with positive and negative particles that keep the matter together. These positive and negatively charged particles, which are now known as protons and electrons, were only recognized after the discovery of the atom.

But here the history of the atom goes back even further

Latin scientists, Democritus and Leucippus have independently developed the thought of an atom & named it “Atom”, a Latin word which means unbreakable. That’s why; the history of atom goes as back in the fourth century B.C.