Physical education

Physical Education is "education through the physical". It aims to develop students’ physical competence and knowledge of movement and safety, and their ability to use these to perform in a wide range of activities associated with the development of an active and healthy lifestyle. It also develops students’ confidence and generic skills, especially those of collaboration, communication, creativity, critical thinking and aesthetic appreciation. These, together with the nurturing of positive values and attitudes in PE, provide a good foundation for students’ lifelong and life-wide learning.

Whether the class produces positive effects on students' health, behavior, and academic performance depends upon the kind of program that is taught. Physical Education programs vary all over the world. However, there are worldwide organizations that allow for a better understanding on how much exercise a child should be getting daily. Popular games in PE include football, netball, hockey, rounders, athletics and cricket.

Physical education trends have developed recently to incorporate a greater variety of activities besides the skills necessary to play typical team sports such as football or basketball. Introducing students to activities like bowling, walking/hiking, or Frisbee at an early age can help them develop good activity habits that will continue into adulthood.

Some teachers have begun to incorporate stress-reduction techniques such as yoga, deep breathing and Tai chi. Tai chi, an ancient martial arts form focused on slow meditative movements, is a relaxation activity with many benefits. Studies have shown that it enhances muscular strength and endurance, as well as cardiovascular endurance. It also provides psychological benefits such as improving general mental health, concentration, awareness and positive mood.[5] It can be taught to any age student with little or no equipment, making it ideal for mixed ability and age classes. Tai chi can easily be incorporated into a holistic learning body and mind unit.

Teaching non-traditional sports may also provide motivation for students to increase their activity, and can help them learn about different cultures. For example, while learning about lacrosse in the Southwestern United States, students might also learn about the Native American cultures of the Northeastern United States and Eastern Canada, where the sport originated. Teaching non-traditional (or non-native) sports provides an opportunity to integrate academic concepts from other subjects as well, which may now be required of many PE teachers. Non-traditional sports add benefits and challenges for those who often get easily distracted, are uncoordinated, or have less interest in traditional sports, which helps to make PE classes accessible to as wide a group of children as possible.

PE is very important to students' health and overall well-being. The Centers for Disease Control and Prevention states that between 2015-2016, the prevalence of obesity in preschool-aged children (ages 2–5) was 13.9%, school-aged children (ages 6-11) was 18.4%, and adolescents (ages 12-19) 20.6% among U.S. youth. Since the 1970s the number of children who are obese has tripled.

Examples of Physical Education in 1912 Toledo, Ohio

SHAPE America's National Standards & Grade-Level Outcomes for K-12 Physical Education define what a student should know and be able to do as result of an effective physical education program.

Another trend is the incorporation of health and nutrition into the physical education curriculum. The Child Nutrition and WIC Reauthorization Act of 2004 required that all school districts with a federally-funded school meal program develop wellness policies that address nutrition and physical activity. While teaching students sports and movement skills, PE teachers are now incorporating short health and nutrition lessons into the curriculum. This is more prevalent at the elementary school level, where students do not have a specific Health class. Recently most elementary schools have specific health classes for students as well as physical education class. Due to the recent outbreaks of diseases such as swine flu, school districts are making it mandatory for students to learn about practicing good hygiene along with other health topics. Children have a primary responsibility of attending school and providing evidence that they are achieving the content standards of their given grade level. If children engage in unhealthy behaviors like poor eating habits, obtaining an insufficient amount of sleep, or overindulging in screen time or other sedentary behaviors, they are less likely to experience developmentally appropriate learning.

Today, many states require Physical Education teachers to be certified to teach Health courses. Many colleges and universities offer both Physical Education and Health as one certification. This push towards health education is beginning at the intermediate level, including lessons on bullying, self-esteem and stress and anger management.

Research has shown that there is a positive correlation between brain development and exercising.

Incorporating local indigenous knowledge into physical education can lead to many meaningful experiences and a way of learning about other cultures. For example, by incorporating traditional knowledge from varying indigenous groups from across Canada, students can be exposed to many concepts such as holistic learning and the medicine wheel. A unit could be focused on connecting to a place or feeling while outdoors, participating in traditional games, or outdoor environmental education. These types of lesson can easily be integrated into other parts of the curriculum and give Aboriginal students a chance to incorporate their culture in the local school community.

Studies have been done in how physical education can help improve academic achievement. In a 2007 article, researchers found a profound gain in English Arts standardized testing test scores among students who had 56 hours of physical education in a year, compared to those who had 28 hours of physical education a year.

In Brazil, the physical education curriculum is designed to allow school pupils a full range of modern opportunities, including sports. Martial arts classes, like wrestling in the United States, and Pencak Silat in France, Indonesia, and Malaysia, teach children self-defense and to feel good about themselves. The physical education curriculum is designed to allow students to experience at least a minimum exposure to the following categories of activities: aquatics, conditioning activities, gymnastics, individual/dual sports, team sports, rhythms, and dance.

In these areas, a planned sequence of learning experiences is designed to support a progression of student development. This allows kids through 6th grade to be introduced to sports, fitness, and teamwork in order to be better prepared for the middle and high school age. In 1975, the United States House of Representatives voted to require school physical education classes include both genders. Some high school and some middle school PE classes are single-sex.

Technology use in physical education:

Many physical education classes utilize technology to assist their pupils in effective exercise. One of the most affordable and popular tools is a simple video recorder. With this, students can see the mistakes they're making in things such as a throwing motion or swinging form. Studies show that students find this more effective than having someone try to explain what they are doing wrong, and then trying to correct it. Educators may use technologies such as pedometers and heart rate monitors to make step and heart rate goals for students.

Other technologies that can be used in a Physical Education setting include video projectors, GPS and games and gaming systems such as Kinect, Wii Fit and Dance Revolution. Projectors can show students proper form or how to play certain games. GPS systems can be used to get students active in an outdoor setting, and active exergames can be used by teachers to show students a good way to stay fit in and out of the classroom setting. Simulators are an efficient way to help promote being active in certain settings. Along with video projectors, GPS and game systems such as Kinect and Wii, simulators where the participant is using goggles to be put in a certain setting are beneficial. One method commonly used in the elderly that could benefit children would be a horse-riding simulator. This simulator allows the participant to be put into a country setting where they are free to roam multiple fields. This simulator is scientifically proven to help balance as well as stability. Relaxing the brain allows for better cognitive function leads to better test results in the classroom as well.

Another type of technology that is commonly used in Physical Education is the pedometer. This does not necessarily track how far a person is going, but lets them know the number of steps they are taking.

----------------------------------------------------------------

Reference:                                                             Wikipedia

For More Topics Visit : https://mytopics4all.blogspot.com

----------------------------------------------------------------

National Integration

To combine and bring together all the people of a country is known as national integration. It is a feeling which combines all the people irrespective of their colour, race, caste, region and religion etc. It is the only force with the help of which all types of people live together peacefully and considering themselves the members of single whole.

THE STATE OF NATIONAL INTEGRATION IN PAKISTAN:

Pakistan is facing the problem of national integration since its creation. The lack of national integration is a big problem. Owing to the absence of national integration Pakistan has been pushed to cruel circle. It has made Pakistan a sorry state of affairs, and has made Pakistan the centre of terrorist activities.

Due to this problem Pakistan has become an instable and vulnerable state and a total breakdown of state machinery. This was not the problem at first. Pakistan was the result of integration on the basis of Islam. Unfortunately after the death of Quaid-e-Azam the country was isolated. National integration faced too many problems.

At this rate, income inequalities, social injustice, political blow and other evils raised their heads. All of these made national integration weak and fragile. There is lack of consensus on important national issues in Pakistan.

For that reason the provinces hate each other. The Punjab is being accused by the rest of three provinces i.e. Sindh, Khyber Pukhtunkhwa and Baluchistan for exploiting their resources and not paying there just share. Sindh, Baluchistan, and Khyber Pukhtunkhwa are against the construction of Kala Bagh dame while Punjab wants to construct it.

On the issue of NFC award the three provinces having the same reservation from Punjab. There are too much hurdles and difficulties in the way of national integration of Pakistan. It is necessary to vanish the sentiments of regionalism or provincialism linguistics or communalism etc.

Some of the important reasons of the failure of national integration of Pakistan are as below:

CRISIS OF LEADERSHIP:

After the death of Quaid-e-Azam there was hardly any leader upon whom the nation could be united. Every leader prefers his personal interest rather than national interest. They built up economic assets on illegal means. Thus they exploited the national purse on the coast of national interest and promoted personal interests. Therefore national integration remained weak and fragile.

ECONOMIC DISPARITIES:

There is a big gap between rich and poor. The system of Pakistan has been structured such that the gulf between poor and rich become widen with the every passing day. Rich become richer and the poor become poorer and poorer. It strengthens the upper and privileged class of society. It never cares of the lower class of the society. Thus the economic inequalities led towards the weakness of the national integration.

PROVINCIAL BIASES AND SOCIAL INJUSTICE:

Beside the lack of social justice and provincial biases are posing a threat to the basic existence of the country. It leads towards the destabilization of the state and shaking the basis of national integration of the country. The smaller provinces have developed the sense of deprivation. They think that they have been deprived of their just share in the national exchequer and of their just royalty. It has developed the age-old animosities among the provinces.

Social justice is the only solution of national integration in Pakistan. The water dispute existed among the provinces. It has posed a major threat to national integration. The provinces have objections on the construction of Kala Bagh dam which has detracted the confidence and unity of the country.

Likewise the dispute over NFC (National Finance Commission) award also posing serious threats to national integration. The provinces don’t agree on the formula in which the resources are to be divided on the basis of population. This creates great hurdles in the way of national integration of Pakistan.

MILITARY INTERVENTION:

Military intervention has weakened the basis of national integration. During military rule the small provinces has been deprived of there just share. East Pakistan seceded during military rule. The military regime failed to promote the sense of ones in the two wings of Pakistan.5 Baluchistan issue also emerged during military rule.

POLITICAL INSTABILITY:

Political stability is the most important prerequisite for strengthening the national integration. Unfortunately Pakistan is lacking this requirement since very long. The political instability has widened the gulf between the ruling class and the ruled class. It has distorted the picture of Pakistan and made it retrogressive in all spheres. Political instability has posed a big threat to national unity and integrity.

Lack of unity and integration has pushed behind the objectives for which Pakistan was created. It has also rhythm of national progress. As a result the nation has become hallow from within in terms of national integration.6

LANGUAGE PROBLEM:

Pakistani is a plural society. There are living many linguistic groups which is problem. Some time it poses serious threats for the geographical integrity of the state. Pakistan lost its eastern wing owing to

many problem of which the language problem was one of the important problem. In today’s Pakistan the difference of language is still a problem in the way of national integration of state. It is very much important for Pakistan to have a language policy which is helpful for the promotion of all languages equally. The current policy has created a sense among the small linguistic groups that the government is only promoting Urdu at the coast of regional languages. All the provinces have been divided into more than one linguistic group which contributing to the instability of country.

MEDIA:

Media is a source of information and education. It is the most effective mean of change and information. Media is expected to play a positive role in image building of the state. It is the responsibility of media to promote national interest and national integration. In a democratic society the role of media is to be of a watchdog. It is the need of the time that our media should strive for building of soft and positive image of the state.

POWER OF MEDIA:

Media is a link between people and societies. Without media they would have been isolated. In the current century media has very much powerful. With the help of media we came to know about the happenings around the world. It unveils the truth and injustice done to people. It rules over the mind of the people. Media educate the people and moulds their opinion, making and toppling the governments makes a hero a villain and a villain a hero. It changes the life style, thinking, culture and tradition of a society.

Power of media can be judged through its role as a source of information, education and entertainment. It has changed the world into a global village.

ROLE OF MEDIA IN NATIONAL INTEGRATION:

Pakistani media is playing very irresponsible role. Talk shows and political debates don’t consider themselves subject to limits. In debates the participants using abusive language against each other. The anchor persons are fuelling the arguments and counter arguments. They don’t care for the fact that what type of image they are going to develop publically. What the people will think about them. This trend is conveying a very negative massage inside and outside of the country.

In the name of freedom of press media, some time crossing the limits. There is a race among the different channels for breaking news which led to a fierce situation. They are using negative tools for increasing the number of viewership.

Media has to play a positive and productive role in a society. Education is one of the important factors in promoting national integration.

RELIGIOUS PROGRAMMES AND NATIONAL INTEGRATION:

There are so many so called religious programmes in which religious scholars appear who came on different TV channels and interpret Islam from their own perspective and point of view. They are crazy of popularity, money and modernity. There is a huge gap between the interpretation of modern ulama and the orthodox ulama. There are people who cannot bear either of the opponent group. They turned against each other and especially the followers of orthodox ulama even came on aggression which causes too many problems in our society. Dr Javed Ahmad Ghamdi, Dr Faroop (late) Dr Aamir Laiqat Hussain is among the modern ulam. Orthodox ulama have issued fatwas against them. The death of Dr Farooq is being connected with this opposition of ideas among orthodox and modernists. He was given threats to take his modern ideas back or then get ready for drastic consequences.

CONCLUSION:

Without media neither we can formulate an opinion nor can resolve any problem. Media has the potential of projecting any culture and give a sense of belonging to people belonging to different backgrounds. But unfortunately there are many examples where media could not come up with the expectations of the people.

From the above discourse it reveals that media in Pakistan does not deliver according to the needs of the nation. Their more concentration remains on market. How to increase the number of viewership, how to attract advertisers and how to break fresh news before any other do it. In this race and competition they often broadcast false and sensitive news.

Media is the most responsible institution of any state. In a state like Pakistan its responsibilities are more sensitive than any other country. Today Pakistan is the focal point of the world. All the countries have interest in Pakistan and thus they analyzing the situation every minute.

Ethnicity:

Ethnicity is a term used to describes shared culture the practices, values, and beliefs of a group. This might include shared language, religion, and traditions, among other communities.

Examples:

German or Spanish ancestry etc.

Explanation:

Ø  Like race, the term ‘ethnicity’ is difficult to describe and its meaning has changed overtime.

Ø  And like race, individuals may be identified or self-identify with ethnicities in complex, even contradictory ways.

Ø   For example, ethnic groups such as Irish, Italian American, Russian, Jewish, and Serbian might all be groups whose members are included in the racial category ‘white’.

Ø  Conversely the ethnic group British includes citizens from a multiplicity of racial backgrounds: black, white, Asian, and more plus a variety of race combinations.

CLASS, CASTE AND BIRADRI SYSTEM IN PAKISTAN’S SOCIETY:

Social stratification refers to arrangements of any group or society into a hierarchy of positions that are unequal with regard to power, property and social evolution.

Ø  It is also defined as the distribution of people of society in groups on the basis of their status.

Determinants of social stratification:

According to Max Weber:

        I.            Economic resources.

      II.            Occupation.

    III.            Prestige.

    IV.            Power.

      V.            Education.

    VI.            Political power.

I.                    Economic resources:

The size of landholdings in rural areas belongs to upper classes. While the tenants, blacksmiths, cobblers, barber, belong to lower class.

II.                  Occupation:

Landowners, industrialists, businessmen, high government officials, corporate officials belong to the upper class.

Servicemen, small businessmen, whose income equals to their expenditures, are the middle class.

Manual workers, carpenters, blacksmiths, washer men all constitute the lower class.

III.                Prestige:

Respect of an individual in society is related to the level of prestige that he enjoys.

Prestige includes nobility, harmlessness, participating in social welfare projects, helping the needy etc.

IV.                Power:

Power gains one respect. In Pakistan following characteristics could be important;

Outspoken in public, educated, well off in financial resources, interest I solving people’s problems, active, religious oriented etc.

V.                  Caste:

Caste system in Pakistan is an important element in social stratification. Some castes are considered high, some are low.

VI.                Education:

Education like all other societies in the world, defines social status in Pakistan too.

Educated people are better rated and respected socially owing to their occupations, professions and status while illiterate people always belong to lower class.

Biradri system:

It is the group of people belonging to same caste, intermarrying together.

Two or more families related to each other are called biradri. People of biradri do not necessary live at the same place. There may be different languages, styles, and customs in biradri.

Old biradries having same caste are still strong in Pakistan. They have more rigid norms.

Social violations in biradries are strictly condemned.

Endogamy is a strict condition in some of the biradries.

 ----------------------------------------------------------------------------------------------------------

For More Topics Visit : https://mytopics4all.blogspot.com

------------------------------------------------------------------------------------------------------ 

Sectarianism

Sectarianism is a form of prejudice, discrimination, or hatred arising from attaching relations of inferiority and superiority to differences between subdivisions within a group. Common examples are denominations of a religion, ethnic identity, class, or region for citizens of a state and factions of a political movement.

Damaging Effects of Sectarianism in Islam:

Sectarianism is one of the worst issue still exist among Muslim society until today. It has a long history behind, but sectarianism passed down through generation that make it lasts this long. It cause disunity among Muslims and in the end threatening the unity of Islam. Sectarianism cause conflict within Muslims which make them weaker to face the enemies from the outside.

“And surely this brotherhood of yours is a single brotherhood, and I am your Lord and Cherisher, therefore fear Me and no other. But people have broken their religion into sects, each group rejoicing in that which is with them. But leave them in their confused ignorance for a time.” *Qur’an, 23:52-54]

The damaging effects of sectarianism in Islam are so severe that it has to be avoided and prevented in any ways. Here are all the effects of sectarianism in Islam:

1. Disunity in the Society:

Sectarianism causing disunity within the society to grow, and it gets no better by the day. Disunity is the root of many problems and disunity among within the society may cause disunity in the bigger part such as in religion and in country. Also read: How to Prevent Envy in Islam

The Prophet has stated in a Hadith,

“No community differed after (the demise of) their Prophet except that the people of their falsehood gained mastery over the people of their truth.”

2. Disunity in Islam:

Islam is a religion that aimed for peace in everyday life and shouting the unity for Muslims. Islam is one and not to be divided by anything.

“As for those who divide their religion and break up into sects, you (Muhammad) have no part of them in the least. Their affair is with Allah; He will in the end tell them the truth of all that they did.” *Qur’an, 6:159+

3. Disunity in Countries:

A disunited country indicated by war that break in within. It usually started with the disunity in the society level that spread widely across the nation, and it somehow unresolved. As the conflict growth, it finally reaches the country level. Also read: Importance of Brotherhood in Islam

4. Grow Dispute and Hatred Toward Each Other:

For Islam to be a solid religion, Muslims should live in peace and unity. Thus, sectarianism that divided Muslim is not something to be kept.

“Surely, this brotherhood of yours is a single brotherhood, and I am your Lord and Cherisher, therefore serve me and no other. But they broke their religion into sects among them; yet they will all return to Us.” *Qur’an, 21:92-93]

5. Causing the War to Happen Easily:

As mentioned above, sectarianism caused dispute and hatred to grow easily within the society and once it gets bigger, it threaten the unity of a country. The worst thing could happen is war within the nation. Islam is one, so there should’t be any division in it. Also read: Dangers of Hedonism in Islam

“And surely this brotherhood of yours is a single brotherhood, and I am your Lord and Cherisher, therefore fear Me and no other. But people have broken their religion into sects, each group rejoicing in that which is with them. But leave them in their confused ignorance for a time.” *Qur’an, 23:52-54]

6. Keeping Away Peace from Life:

Living in peace is something that everyone in the world wish for. However, it almost impossible if the society is threatened by sectarianism. Instead of peace, war may break at any time, causing people to stay alert and uneasy.

“The believers are but a single Brotherhood. So make peace and reconciliation between your two contending brothers, and observe your duty to Allah, that you may receive mercy.” *Qur’an, 49:10-11]

7. Disregarding Allah’s Command:

Allah SWT hates war. Unless to fight the kufr and evil, war between Muslims is a big sins and loss for Islam itself. Allah SWT has clearly command us to live in peace, not the other way. Also read: Sign Your Tawbah Accepted

“Turn back in repentance to Him, and fear Him. Establish regular prayers, and be not among those who ascribe partners to Allah – those who split up their religion, and become mere sects, each party rejoicing in that which is with itself!” *Qur’an, 30:31-32]

8. Causing Violence Between Muslim:

War and violence are extremely close whenever sectarianism is around. It damaging the society, creating an unhealthy environment to live in for everyone.

9. Damaging the Economic Aspect:

Sectarianism cause a domino effect in every layer of society’s life. After taking the peace, next would be the economic aspect to be damaged by it. Also read: Purpose of Islamic Economy in Life

10. Causing Disharmony in Politics:

Sectarianism can be used for wrong political interest. Some parties purposely causing dispute and war for their own advantages.

11. Creating Lack of Tolerance in the Society:

Social life would be severely damaged by sectarianism in every aspect. It also diminished the tolerance in the society, causing them to live in hatred every other day. Also read: Importance of Relations in Islam

Future Of Pakistan:

Pakistan, a country that is always a crucial part of world affairs,a place that is known for global Jihad and is the second largest Muslim population. From the day it has been separated and became an independent country until now there is a lot ups and down which has it has faced.

Pakistan is a hub of natural resources but require useful utilization of these resources, besides its greatness it has faced a lot of trouble in these previous years. However, the current prime minister of Pakistan is thought to eliminate all the bigger issues but again people of Pakistan are waiting for all these betterment to take place.

The thing is that relationship with the global world matters a lot when any country is developing or moving towards development. Here, it is always confusion and thing is never the same. Countries like America, Russia, China, turkey and other states that have always supported us in making things well but still Pakistan face hurdle on the critical situation that which side needs to be chosen and to whom we support at the time of difficulty. Writers from thesis writing services in Pakistan has written a lot of article regarding these issues.

The most worrisome thing is that Pakistan situation is diluted with billions of dollar loan. There is a lot of time to overcome this heavy burden that each person of Pakistan has. Moreover, Pakistanis should now stop compromising over things that bother them. they should not act as separate party and work together to enforce the government wrong decisions.

Most of the people think that Pakistan’s alliances with two powerful nations that are America and China can make a bright future. Deeply analysis this situation so Pakistan has already staked its current situation by depending on these two nations. It should had made relationship with other international countries to strengthen its basis. However, even now powerful steps can be taken but it seems too difficult and sacrificial.

According to World Bank report, what should Pakistanis do for brighter future till 2047 has some intriguing points. It advice Pakistan to start making the wiser decision now comparing to other countries like South Korea and china they have amazingly transformed their economies so why not Pakistanis.

In this report, Pakistan is suggested, to invest in people, caring for the environment, using the resources efficiently and support its growth by implementing difficult reforms. The more any nation contributes to its nation the more it can be beneficial for them in future. A productive population is the most aspiring thing a nation can have. Government should focus on quality of life of people, easing the transportation system and increasing the number of facilities, education, business and all other areas.

The point that is the most fundamental besides all these discussion is Pakistan’s future can only be shaped by its people. As a nation its people should get united to make things better and make this country a better place with love, peace, and harmony

   The members of this class of hydrocarbons contain two hydrogen atoms less than the corresponding alkanes. The two valency bonds left free on the adjacent carbon atoms unite to form a second union between them, establishing , π double bond in the molecule.

Since fill the valencies of the carbon atoms in alkenes are not fully satisfied, they can take up more H-atoms and are called Unsaturated hydrocarbons.

  The hydrocarbons of this cla.ss are frequently called Olefines (Olefiant=oil forming) as the first member of the class, ethylene reacted with chlorine to form an oily product.

Cracking of petroleum:

    Alkenes being much more reactive than alkanes seldom occur free in nature.They are, however, produced in Iarge amounts during the cracking of petroleum a:nd the decomposition of almost all organic substances. The cracking of cotton seed oil gives as much as 30 per cent yield of ethylene. The lower alkenes occur to a minor extent in coal gas.

Structure:

 Bond hybridization:

   Let us consider ethylene, in ethylene the carbon bonds are sp2 hybridize. They are attached to each otherby a sigma bond and a pi bond. The sigma bond results from the overlap of two sp2 hybrid orbitals( i.e. one from each carbon). The pi bond is formed from the overlap of the unhybridized p orbitals.

Remember:

1)      The carbon-carbon double bond in alkenes is made up of one sigma bond and one pi bond

2)      Alkenes are more reactive than alkanes. This is due to the availiability of the more exposed pi electrons.

NOMENCLATURE:

  The COMMON NAMES:

The common names of the first four members (C₂ to C₅) are derived from those of the corresponding alkanes (having same No. of carbons) by changing the ending -ane to -ylene. Grcek letters are used to distinguish isomers having double bond at the first (α) or the second (β) carbon of the chain is illustrated above for Butylenes . Thus:

 The ipuac names of alkenes are derived from those of the corresponding alkanes by changing the terminal ·ane to ·ene, Thus to get the name of an individual member, first name the alkane with the same number of carbon atoms ana then replacing the ending  ane by.ene, Thus:

When there are two or three double bonds in a molecule, the ending ane of the rcspective alkane is replaced by  diene or  triene to get the name of the hydrocarbon. Thus

AlkenyI radicals.

    The monovalent radicals obtaincd from alkenes are called alkenyl radicals 'I'he common names vinyl radical and allyl radical are also the IUPAC names.  All other alkenyl radicals arc named by replacing the 'e' of the parent alkene by '.yl.' The carbon atoms constituting the radical are numbered So that the carbon with free velency is always number 1. The IUPAC names of some aIkenyl radicals are given below:

ISOMERISM:

  The presence of the double bond in alkenes increases the opportunity of isomerism. In addition to chain isomerism, they offer position isomerism due to the different positions of the double bond on the carbon chain.

The first two alkenes can have but one structural formula. The third member butene, however, can have three possible structural formulas

All the three butenes are actually known. The compounds (1) and (2) present a case of position isomerism as they differ only in the location of the double bond. The compounds (2) and (3) illustrate both position and chain isomerism.

Besides the structural isomerism, certain alkenes also show cis-trans isomerism. Thus 2-Butene is known to exist in two forms.

What is a pure substance?

A pure substance has no particles of any other substance mixed with it. In real life, very few substances are 100% pure. For example tap water contains small amounts of many different particles (such as calcium ions and chloride ions). The particles in it are not usually harmful – and some are even good for you.

Distilled water is much purer than tap water, but still not 100% pure. For example it may contain particles of gases, dissolved from the air.

Does purity matter?

Often it does not matter if a substance is not pure. We wash in tap water, without thinking too much about what is in it. But sometimes purity is very important. If you are making a new medical drug, or a flavoring for food, you must make sure it contains nothing that could harm people.

An unwanted substance, mixed with the substance you want, is called an impurity.

How can you tell if a substance is pure?

Chemists use some complex methods to check purity. But there is one simple method you can use in the lab: you can check melting and boiling points.

·         A pure substance has a definite, sharp, melting point and boiling point. These are different for each substance. You can look them up in table

·      When a substance contains an impurity:
*Its melting point falls and its boiling point rises
*It melts and boils over a range of temperatures, not sharply.

·         The more impurity there is:
*the bigger the change in melting and boiling points
*the wider the temperature range over which melting and boiling occur.

Separation: (The first step in obtaining a pure substance)

        When you carry out a reaction, you usually end up with a mixture of substances. Then you have to separate the one you want. The table below shows some separation methods. These can give quite pure substances.

Separating a solid from a liquid:

Which method should you use? It depends on whether the solid is dissolved, and how its solubility changes with temperature.

           1)      By filtering:

        For example, chalk is insoluble in water. So it is easy to separate by filtering. The chalk is trapped in the filter paper, while the water passes through. The trapped solid is called the residue. The water is the filtrate.

2) By crystallization:

        You can obtain many solids from their solutions by letting crystals form. The process is called crystallization. It works because soluble solids tend to be less soluble at lower temperatures. For example:

3) By evaporating all the solvent:

                For some substances, the solubility changes very little as the temperature falls. So crystallization does not work for these. Salt is an example

        ·          To obtain salt from an aqueous solution,
          you need to keep heating the solution, to
          evaporate the water.                    

       ·      When there is only a little water
         left, the salt will start to appear.
          Heat carefully until it is dry.

Separating a mixture of two solids:

To separate two solids, you could choose a solvent that will dissolve just one of them. For example, water dissolves salt but not sand. So you could separate a mixture of salt and sand like this:

·         Add water to the mixture, and stir. The salt dissolves.

·         Filter the mixture. The sand is trapped in the filter paper, but the salt solution passes through.

·         Rinse the sand with water, and dry it in an oven.

·         Evaporate the water from the salt solution, to give dry salt.

Water could not be used to separate salt and sugar, because it dissolves both. But you could use ethanol, which dissolves sugar but not salt. Ethanol is flammable, so should be evaporated over a water bath, as shown here.