Note on groups and periods in the modern periodic table....
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Answer:the periodic table has undergone extensive changes in the time since it was originally developed by Mendeleev and Moseley. Many new elements have been discovered,while others have been artificially synthesized. Each fits properly into a group of elements with similar properties. The periodic table is an arrangement of the elements in order of their atomic numbers so that elements with similar properties apper in the same vertical column or group. Period A period is a horizontal row of the periodic table.There are seven periods in the periodic table,with each one beginning at the far left. A new period begins whe a new principal energy level begins filling with electrons. Period 1 has only two elements,while periods 2 and 3 have 8 elements.Periods 4 and 5 have 18 elements.Periods 6 and 7 has 32 elements because the two bottom rows that are separated from the rest of the table belongs to those periods.They are pulled out in order to make the table itself fit more easily onto a single page. Groups
Answer:the periodic table has undergone extensive changes in the time since it was originally developed by Mendeleev and Moseley. Many new elements have been discovered,while others have been artificially synthesized. Each fits properly into a group of elements with similar properties. The periodic table is an arrangement of the elements in order of their atomic numbers so that elements with similar properties apper in the same vertical column or group. Period A period is a horizontal row of the periodic table.There are seven periods in the periodic table,with each one beginning at the far left. A new period begins whe a new principal energy level begins filling with electrons. Period 1 has only two elements,while periods 2 and 3 have 8 elements.Periods 4 and 5 have 18 elements.Periods 6 and 7 has 32 elements because the two bottom rows that are separated from the rest of the table belongs to those periods.They are pulled out in order to make the table itself fit more easily onto a single page. Groups A group is a vertical column of the periodic table,based on the organization of the outer shell electrons. There are a total of 18 groups. There are two different numbering system that are commonly used to designate groups.The traditional systems used in the United States involves the use of the letters AandB.The first two groups are 1A and 2A,while the last six groups are 3A through 8A.The middle groups use B in their titles. Unfortunately,there was a slight different system in place in Europe. To eliminate confusion the International Union of Pure and Applied Chemistry (IUPAC) decided that the official system for numbering groups would be a simple 1 through 18 from left to right.Many periodic tables show both systems simultaneously.