What are 2 main divisions of the periodic table?

Answer 1

DEFINITION:The orderly arrangement of elements is called "PERIODIC CLASSIFICATION".

INTRODUCTION: When a very large number of elements become known to scientists , it was felt that they must be arranged in a systematic order because a systematic classification provides a clear idea and information about the properties of elements and make it easier to predict the properties of different elements. This classification provides the inter-relationship of scientific facts.

Early Attempts at Classification Of Element:In old days, element were arranged in the ascending order of their atomic masses.

1.Law of Triads/ DOBEREINER'S TRIADS:In 1829, a German scientist Dobereiner made use of the relationship between atomic masses and properties of elements.

Drawback:This rule is not for all the elements.

2.NEWLAND'S law of octave:In 1866, a British scientist, Newlands, reported his "law of octave" by arranging elements according to increasing order of their atomic masses. He noticed that "Every eight element, starting form any point, approximately has similar properties".

Newland's arrangement was applicable only to a few elements after that it was failed.

3.LUTHER MEYER'S CLASSIFICATION:In 1864, a German Chemist Luther Meyer published on incomplete Periodic Table .He included about 56 elements arranged in a group from I to VIII. He plotted the values of different physical properties and obtained different curves .In these graphs, he observed that element with similar physical properties occupy similar positions in the curve

For example :Alkali metals occupy the peak of the curves.

Halogen occur on the ascending portions of the curve.4.MENDELEEV'S PERIODIC TABLE:

In 1869, a Russian chemist, Mendeleev, on the basis of physical and chemical properties discovered a relation known as "PERIODIC LAW".According to the law:"The properties of element are the periodic function of their atomic masses".

Mendeleev arranged the known elements according to increasing order of their atomic masses because,according to him fundamental property of an element was Atomic Mass.He further divided and arranged these eight groups into subgroups.Mendeleev's periodic table was very precise and provided the basis of modern periodic classification.

Original statement of Mendeleev's periodic law:

1.The elements,if arranged according to their atomic weights show an evident periodicity of properties.

2.Elements which are similar with regards to their chemical properties have atomic weights which are either nearly the same value or which increase regularly.

3.The arrangement of the elements or of groups of elements in the order of their atomic weights,corresponds with their so called valencies.

4.The elements which are most widely distributed in nature have small atomic weights and sharply defined properties.They are therefore typical elements.

5.The magnitude of the atomic weight determines the character of an element.

6.The discovery of many as yet unknown elements may be expected.

7.The atomic weight of an element may sometimes be corrected by the aid of a knowledge of those of adjacent elements.

8.Certain characteristic properties of the elements can be foretold from their atomic weights.

MERITS OF MENDELEEV'S PERIODIC TABLE

Mendeleev's periodic table offered the following advantages in understanding the properties of elements.

1. There was a regular gradation in physical and chemical properties of elements.

2. The group number of an element indicates highest oxidation state that it can attain.

3. There were many vacant spaces in Mendeleev's periodic table for the elements to be discovered.He named them Eka-Boron, Eka-Aluminium and Eka-silicone He also predicted the properties of these undiscovered elements including atomic masses.These elements were discovered as Sc ,Ga and Ge with same features as he predicted.

4. Mendeleev's arrangement helped to correct atomic masses of a number of elements.

DEMERITS IN MENDELEEV'S PERIODIC TABLE

1. For placing the elements in proper groups,the order of the elements according to atomic mass was reversed in certain cases. He placed Iodine (127) after Tellurium (128) Potassium (39) and Ni (58)after Co (59).Which is against his periodic law but correct according to properties.

2. Mendeleev's periodic table does not provide a clear idea about the structure of atom.

3. Lanthanide and Actinide have been assigned places in the periodic table which is against the periodic law.

4. Alkali metal and coinage metals (Cu,Ag and Au) which differ widely in properties are placed into the same group.

5. There is no separate position for isotopes in his periodic table.

6. The change in atomic mass of two successive elements is not constant. Hence it is not possible to predict the number of missing elements by knowing the atomic masses of two known elements. DIC TABLE1. For placing the elements in proper groups, the order of the elements according to atomic mass was reversed in certain cases. He placed Iodine (127) after Tellurium (128) Potassium (39) and Ni (58) after Co (59). Which is against his periodic law but correct according to properties.

2. Mendeleev's periodic table does not provide a clear idea about the structure of atom.

3. have been assigned places in the periodic table which is against the periodic law.

4. Alkali metal and coinage metals (Cu, Ag and Au) which differ widely in properties are placed into the same group.

5. There is no separate position for isotopes in his periodic table.

6. The change in atomic mass of two successive elements is not constant. Hence it is not possible to predict the number of missing elements by knowing the atomic masses of two known elements.

DEMERITS IN MENDELEEV'S PERIODIC TABLE

1. For placing the elements in proper groups, the order of the elements according to atomic mass was reversed in certain cases. He placed Iodine (127) after Tellurium (128) Potassium (39) and Ni (58) after Co (59). Which is against his periodic law but correct according to properties.

2. Mendeleev's periodic table does not provide a clear idea about the structure of atom.

3.have been assigned places in the periodic table which is against the periodic law.

4. Alkali metal and coinage metals (Cu,Ag and Au) which differ widely in properties are placed into the same group.

5. There is no separate position for isotopes in his periodic table.

6. The change in atomic mass of two successive elements is not constant. Hence it is not possible to predict the number of missing elements by knowing the atomic masses of two known elements.

Answer 2

A group in the periodic table fits into a vertical column, so the first column is group 1, the alkali metals, lithium, sodium, potassium etc. They are grouped according to their abilities to combine with other elements, in other words there will be a common theme to their behaviour. So all the metals in group 1 will react with water in the same way, but you will see a trend as the behaviour shifts in nature down the group. In group 1 the reactivity increases down the group, so the metals fizz more vigorously when dropped into water.

Answer 3

Yes. The two main classification of elements in the periodic table are metals and nonmetals.

Answer 4

There are eight groups that make up the main group elements. They are groups 1, 2, and 13 - 18. They are also called the representative elements.

Answer 5

There are three main groups of elements on the Periodic Table. They are Metals, Metaloids, and Non-Metals. Metaloids have properties of both metals and non-metals.

Answer 6

by atomic number and atomic mass

the periodic table is organized into periods and groups

Answer 7

none! a group is a row of elements on the periodic table that goes from top to bottom, and each group or groups is classified into families. there are about 10 elements in one group.

Answer 8

Metals and nonmetals

Answer 9

metal and non metal