2. X3+  has 10 electrons. What is the group and the period number of X atom in the table?

 

                    In 1869, Dimitry Mendeleev and Lothar Meyer independently made a similar classification of elements. Both of them arranged the elements in the order of increasing atomic weight. 

                    Mendeleev arranged 63 elements in his table. He placed the elements having similar chemical properties in the same vertical columns. He left some blank spaces on his table and said that these elements are going to be discovered. He guessed some elements(For example; Ga, Ge, B, Fr, As) going to be placed into these blank places. He estimated the boiling points, melting points and atomic weights of these elements before they were discovered. These data were proved with small differences when these elements were discovered and it made Mendeleev popular.

                    After Mendeleev noble gases were discovered and Henry Moseley solved the puzzle of the periodic table. He claimed that atoms should be arranged according to their atomic number(proton number) instead of atomic weight because there are no two different elements with the same proton number. 

                    In the periodic table, the elements are arranged in the order of increasing  atomic number. 

                    Each horizontal row is called a period. There are 7 periods. The 6th and the 7th rows are long periods. 

                    Each vertical column is called a group. There is a total of 16 groups of which 8 are group A and 8 are group B. Group 8B contains three groups. Since the elements in a group have similar chemical properties, a few common groups are given family names.

Group 1A ®Alkali metals                    Group 7A ®Halogens  

Group 2A ®Earth alkali metals          Group 8A ®Noble gases

Group 3A ®Earth metals                     Group B   ®Transition metals