Atomic Structure and the Periodic System Elements

At this time have been found over a hundred elements and so many chemical compounds that have been biosynthesized. How can we easily learn the elements of it? The chemists have grouped elements based on the properties of chemical and physical properties that are similar or the same.

To learn grouping elements by their nature can be used periodic table of elements. Elements Periodic Table of classification evolved from simple to complete. The periodic table used today is the modern periodic table are arranged by atomic number increases and the similarity of the properties of the elements. In the modern periodic table, elements are grouped into classes and periods.

Element on the periodic table, the symbol of the element is equipped with atomic mass and atomic number. From these data we can determine the atomic structure of an element ffffseperti protons, neutrons, electrons and electron configuration.

In the periodic table of elements we unsuir DAPT study the properties of metals, metalloids, non-metals, and the periodic nature of the fingers, enenrgi ionization, electron affinity, and electronegativity.

A. Development of the Periodic Table of Elements

Grouping elements initiated by the Antonine Lavovoisier grouping elements into metals and non-metals. Furthermore, grouping elements developed in various forms and is known by Triade Doberiener, Octave Newlands, Lothar Meyer Periodic Table of Elements and Mendeleve and Modern Periodic Table.

1. Periodic Table of Elements Antoine Lavoisier

Antoine Lavoisier in 1789, a French chemist dividing the elements into four groups. To know the classification, consider Table 1.1.

Table 1.1 Classification of the element by Antoine Lavoisier

Listed in Table 1.1 and the heat instead of light elements. In group IV included compounds that can not be decomposed into elements known today.

2. Law Triade Dobereiner

J.W. Dobereiner in 1817 grouping the elements that have similar properties, each group consisting of three elements called triade.

To study these laws do activities follows.

Dobereiner tried grouping elements that have the same properties of increasing atomic mass, was obtained regularity. If the three elements sorted by atomic mass increases, the mass of the second element equal to the average mass of the first and third elements. This statement is known as the Law of Triade Dobereiner.

3. Newlands Law of Octaves

In 1863, J.W. Newlands sort the elements based on atomic mass increases. How to order a discovery? Try grouping discussed through the following activities

From this grouping apparently the eighth element has similar properties to the first element, as well as elements of the ninth character is similar to the second element, and so on. For example, elements similar to the elements of nature H F and Cl, elements like Li Na and K, as well as elements like Mg Be.

Repetition is the so-called Law of Octaves Newlands as he compared the recurrence properties of elements with scales or octaves on track. Newlands pioneered the preparation of the elements that are similar in vertical columns. Weakness law of octaves that repetition every 8 elements fit only for elements that small atomic mass. In addition there are coincident elements in the same order.

4. Periodic Table of Elements Lothar Meyer

In 1870, Lothar Meyer tried to make a list of the elements with respect to the physical properties of atomic volume. He made the atomic volume graph element to the atomic mass.

To learn how to do the following activities.

In curved Meyer, elements Li, Na, K, Rb, and Cs occupies an equivalent position, which is at the top. Be, Mg, Ca, Sr, and Ba is the second point of the peak. It turns out that the location elements have properties similar equivalent.

5. Mendeleev Periodic Table of Elements

Dimitri Ivanovich Mendeleev in 1869 in Russia put forward the relationship between the mass of an element with the properties of elements. In studying the periodikan elements, Mendeleev than using physical properties also use chemical properties. In research such as New-lands, Mendeleev also arrange elements by atomic mass increases relative and he found no change in the nature of a periodic basis.

Excess Mendeleev periodic table of elements is as follows.

a. The first is the periodic table arranged in the form of eight vertical columns or groups, and seven rows of horizontal or period. Hereinafter referred Mendeleev periodic table of elements.

b. There's an empty place for elements predicted to be found and named eka boron, eka aluminum, and eka silicon. Divination is proved by the discovery of Scandium (1879), Gallium (1875), and Germa-nium (1886). Examples forecast for Germanium Mendeleev called eka silicon listed in Table 1.2.

Mendeleev Table 1.2 Predictions of the nature of the element germanium

c. put the elements He, Ne, Ar, Kr, Xe, and Rn in a separate class after class of noble gases found.

Mendeleev periodic table of elements is described as follows.

Besides advantages, Mendeleev periodic table of elements has several disadvantages as follows.

a. There are some elements of the reverse order when viewed from the increasing relative atomic mass, such as Te (128) placed before the I (127).

b. Triade iron (Fe, Co, Ni), platinum triade light (Ru, Rh, Pd), and platinum triade (Os, Ir, Pt) included in class VIII. Among the elements of this group can only Ru and Os that have valence 8.

6. Modern Periodic Table

Periodic table of elements digunakn now the Modern Periodic Table of Elements. After the periodic table of elements Mendeleev, in 1915 Henry Mosley discover and develop atomic number elements in the periodic table by atomic number increases and menyususun preformance elements of the periodic table by atomic number increases increases. several studies, showing the relationship between the atomic number of the element properties, so Mendeleev table peridik need improvement. Modern elements on the periodic table are arranged in groups and periods

There are 2 numbering system used on golomgan the American system and the IUPAC system. The American system using Roman numerals I through VIII, maing each consisting of class A and B. System IUPAC (International Union Pure and Applied Chemistry) using Arabic agka 1 to 18.

Therefore IPAC group numbering system has not been socialized among chemists, the American sisatem pengolongan more widely used so well in Indonesia.

Modern periodic table of elements are described as follows.






Predictions about the nature of the element germanium Mendeleev


c. put the elements He, Ne, Ar, Kr, Xe, and Rn in a separate class after class of noble gases found.

Mendeleev periodic table of elements is described as follows.
Besides advantages, Mendeleev periodic table of elements has several disadvantages as follows.

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