Periodic Table Of The Elements

In chemistry, one of the most important thing is the periodic table. Where is this table trying to uncover the sequence of chemical elements. For those who are Professional, may not really need this table. Because it is definitely mostly memorized the sequence. It may even be able to explain one by one element.

            The periodic table of chemical elements is the view of the chemical elements in table form.The elements are arranged by electron structure so that the chemical properties of these elements vary regulary  across the table. Each element is listed by its atomic number and chemical symbol. 

Periodic table standard provides basic information about an element. There are also other ways to show the chemical elements with more or load from a different perspective.
Here are the elements of the periodic table:

Reliability

           Reliability is an assessment instrument, the tool in measuring what is measured. This means that whenever the instruments used will yield the same measure. The most obvious example is the scale or meter. The same thing happened to gauge a symptom, behavior, traits or characteristics of individuals and others. For example gauge learning achievement such as achievement test, attitude measuring instruments, questionnaires, etc., should examine the nature of such constancy.

             Achievement test is said to remain if the current measurement results showed similar results at a different time, against the same student. For example, students in grade V on this day in tests of mathematical ability. The next week students in the test back. Results from both tests are relatively similar. Nevertheless is still possible there are differences in results for certain things due to accidental factors, time interval, the change students' views on the same matter. If this happens, the weakness lies in the measuring instrument, which has no certainty or doubt the students' answers. In other words the degree of reliability is still low.

           On the other hand, differences in measurement results is not caused by the measuring tool, but a condition that happens to students. For example, students in a state of physical pain during the first test, the motivation at the time of the first test is different motivations on the next test.

          On the basis of the difference the first measurement results with the results of subsequent measurements can teijadi due to change in subjects who were measured and / or by factors relating to the granting of the test itself. This is not surprising and are common, often expressed with the title / term measurement error. This means, the score of the first measurement results and measurement results of the second score on the same subject, possible measurement errors caused by two factors above. Thus each measurement score results produce two parts, namely the results of the first measurement, called the true score and the results of subsequent measurements on the same subject, which contains the results of the score plus measurement error.

True score and score components that contain errors of measurement is expressed in a mathematical equation as follows:

X = b s,

with:
X = Observed score
b = true score
s = measurement error

In a study score observed was a true score plus measurement error score so that the observed score variance X2 is Tb2 true score variance plus error score variance or Tx2 = Tb2 TS2 TS2.

           Reliability index measuring instrument in a study can be found by correlating the scores obtained from repeated measurements at different times, or with a group of questions is worth it. This procedure is done by giving the test twice to the same subject at different times. The second way is to divide the measuring instrument (test) into two equal parts or the Setarap to view the constancy test. The first way is known to re-test (test retest) and the second way is known as fractional comparable / equivalent.

 
a. Retest reliability

          Retest (test-retest) is the use of measuring instruments on the subject are measured, made twice in different times. For example, mathematics achievement test for fifth grade elementary school students, given today, then checked the results. A week later the test was given again on the same students and the results are examined. The results of the first measurement and then correlated with the results of the second measurement to obtain the correlation coefficient (r). The correlation coefficient is called coefficient of retest reliability, the results will move from - 1.0 to 1.0. When the reliability coefficient close to 1.0 is a high reliability index. This means that the first measurement results are relatively similar to the results of the second measurement. In other words, the instruments have a level of constancy or provisions of (reliable). To measure the social sciences and education reliability index 0.75 was considered sufficient given the nature and the social sciences and education are different from exact sciences.

            The distance or interval between the first measurement with the second measurement should not be too close nor too far. If too close / short, the measurement results are influenced by memories of the students on the answers given at the first measurement, not because the measuring instrument constancy. Conversely, if the first measurement time interval with the second measurement is too long, there could be a change in students' knowledge and experience that affect the reliability coefficient. The assumptions used in the retest is characteristic measured by the measuring instrument is stable over time, so if there is a change score of the two measurements is due to measurement error. How to re-test (test-retest) are widely used in establishing or determining the level of reliability of measurement in social research and education.
 

 b. Reliability equivalent fractions

Reliability is not done a fraction equal to the subject repeated the same measurements but using results from tests of a comparable or equivalent to that given to the same subject at the same time. Thus the required two sets of measuring instruments are arranged in such a way as to have a degree of similarity or equality in terms of, the content, level of difficulty of measuring instruments, abilitas measured, the number of questions, the form of questions and other technical aspects. The difference is only a question. When the constituent instrument of equality can be achieved optimally then the coefficient of reliability of this procedure is considered the most well compared with the retest procedure. But the difficulty lies in setting measurement devices that actually contain a high degree of equality.

  

c. Reliability halved

           Reliability split similar to the reliability of equivalent fractions, especially from its implementation. In this procedure measuring instrument given to the subject just once or one time. Beads of questions divided into two comparable parts, usually distinguish questions about the even number with an odd number. Every part about checked the results, then scores from the two sections correlated to look for correlation coefficients. Given the correlation was only half do not apply to the whole question, then the correlation coefficient was not acquired for the entire problem, but only half. Therefore, the correlation coefficient halved need to be changed into a correlation coefficient for the entire problem by using Spearmen Brown prophecy formula. After doing the conversion. Assumptions used in the split second procedure is the second part of the parallel measuring instrument, though often wrong or incorrect. As a result of the conversion coefficient of reliability, the split second procedure tends to show high reliability coefficients than the re-test procedure and equivalent fractions. Therefore, the use of the split second should be more careful. This procedure is used when measuring devices containing or consisting of many items, the item is relatively heavy / hard (power test), the tested material comprehensive enough to enable the preparation of two questions to one similar problems to meet the split second.

 
d. Similarity rational

           In addition to the ways described above there are procedures for calculating reliability without performing measurements or correlation of two equivalent fractions and the split second. The way it is rational similarity. This procedure is done by connecting each point in one test with other grains and with the test itself as a whole. One way is to use a formula often used Kuder-Rechardson or KR 21.

Validity

          Validity with respect to the accuracy of measuring instruments to the concepts measured, so that only too well what it should measure at ¬ measure. For example, want to measure students' ability ¬ lam da math. Then the given problem with long sentences and complicated, so complicated elusive meaning. Finally students are not able to answer, due to not understanding the question. Another example, researchers wanted to measure the ability to speak ¬ way, but asked about grammar or literature such as poetry or rhymes. Gauge is not accurate (valid). Validity is not universally valid because depending on the circumstances and objectives of his research has ¬. Instruments that have been valid for a particular purpose is not automatically valid for other destinations.Examples of learning achievement and motivation variables can be measured by tests or by questionnaire. The trick can also be different, can test ¬ sanakan relief can be written or oral. There are three types of validity that is often used in the preparation of instruments, namely the validity of the contents, validity build understanding and validity of the forecast.

(a) The validity of the content 
           Content validity with respect to the instruments ability to measure the content of which must be measured. This means that the instruments capable of revealing the contents of a concept or variable to be measured. For example, achievement test social studies subject areas, should be able to reveal the contents of the field study. This can be done by preparing a test derived from the curriculum subject areas to be measured. In addition to the curriculum can also be enriched by seeing / reviewing the book source. Nevertheless achievement test is not possible to disclose all material existing in the field of study tar ¬ of course even if only for one semester. Therefore be taken in part from material in the form of the test sample. As a sample, so it should be able to reflect the material from all subject material. How the test sample taken in defining the concept is to choose the essential concepts of the material in it. For example set a number of concepts of every subject that exists. Of every concept developed at ¬ ing some test questions (see chart). This is where the pen ¬ importance of the role of lattice grid as a tool to satisfy content validity.

(b) The validity build understanding (Construct validity) 
           Validity wake up or wake up understanding (Construct validity) sustain ¬ tion with the ability to measure gauge sense definition contained in the material measured. Pe ¬ sense notion embodied in the concept of ability, interest, as a research variable in different fields of study must be clear what to measure. The concept is still an abstract concept, ¬ trust requires a more specific description, so easily measured. This means that each concept should be developed indikatomya indicators. With the indicator of each concept will get a sense of ease in the visible and specifies how measurement. For certain variables, made possible the use of measuring devices that measure a wide range of different ways.Establish indicators of a concept can be done in two ways, namely (a) use logical thinking or understanding on the basis of the theory of scientific knowledge and (b) use of empirical experience, ie what happens in real life.Example: The concept of "Social Relations", judging from experience, is the relevance of empirical indicators- Can get along with others- Groove or a lot of his friends- Accept others' opinions- Not impose their opinions- Can work together with anyone- And others.Measuring these indicators, means measuring the build understanding contained in the concept of social relations. Another example: The concept of attitude can be seen from the indicator in theory (deductive theory), among others, linkages of- Willingness to receive a stimulus object attitude- Willingness reacts to a stimulus object attitude- Assess the attitude object stimuli- Arrange / organize the attitude object- Internalization of values that exist in the object attitude.If test results show that the test indicators are not positively associated with each other, meaning that size has no validity build understanding. On that basis the indicator needs to be reviewed or corrected return. Another way to determine the validity of the wake is the notion of a gauge link (correlation) between the measuring instruments are made with a standard measuring instrument / standardized, if there has been standardized. When pointed ¬ a high correlation coefficient, the measure meets its validity.

(c) The validity of predictions (predictive validity) 
            Validity of prediction means is associated with certain criteria. In this validity test is preferred but not the content of the criteria, whether the instruments can be used to predict a trait or a certain behavior or certain criteria as desired. Suppose ¬ gauge learning motivation, whether it can be used to predict academic achievement achieved. This means that there is a positive relationship between achievement motivation. In other words it contains characteristics of validity and relevance of constancy or assessments (reliability). Motivation can be used to predict achievement scores when the scores obtained from the size of motivation are positively correlated with achievement scores. The validity of this prediction has two meanings. First the validity of short-term and second term. The validity of the short term, meaning that the instruments predictive power only for the period not longer. That is, scores are correlated at the same time. For example, assessments (reliability) occurred in the second semester means applies predictive power in the second semester, and not necessarily tar ¬ so in the next semester. While long-term validity implies score will be correlated also in the future. Given the validity of this greater emphasis on the correlation, the factors concerning the correlation dongan requirements must be met. These factors include the relationship of the concepts and variables can be explained on the basis of scientific knowledge, the mini ¬ mal sense and not making any sense. Another factor is the score that correlated to meet the linearity. Third validity ¬ explained above should ideally be used in preparing the instrument pe ¬ research has, at least two of validity, the validity of the content and validity of the ba ¬ built understanding. The validity of the content and build understanding ¬ absolutely necessary and can be pursued without testing when statically 

My first article

       Aditya rahman my name was called adit, adhyt, dhyt or adi, I come from the Cirebon area in which the area was named Sindanglaut but I was born in the area sedong the name of his village is windujaya. now lives in Jakarta, a place where many people milling around and densely populated, I live in this town many people (jakarta) may be forced for some reason I have to lecture at a state university in Jakarta is UNJ and I entered the chemical department , majoring in which a lot of writing tasks 5th semester and until now I still write to meet existing coursework. possible on this first post I do not want to write at length enough to know who I am, this is just to start, maybe someday I'll become a professional writer. thanks