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The periodic table organizes chemical elements by atomic number, electron configurations, and chemical properties. It includes periods and groups that indicate recurring properties and valence electrons, respectively. Elements are classified as metals, non-metals, or metalloids based on their physical and chemical characteristics. The table's evolution, from early classifications to Mendeleev's predictions and modern atomic understanding, showcases its importance in chemistry.
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The atomic number represents the number of protons in an element's nucleus, while the atomic mass reflects the average mass of an atom
Elements in the same period share similar chemical properties due to their increasing atomic number
Elements within a group have the same number of valence electrons, resulting in similar chemical reactivity
The s-block contains groups 1 and 2 and is characterized by elements with their highest energy electrons in the s-subshell
The p-block includes groups 13 to 18 and consists of elements with their highest energy electrons in the p-subshell
The d-block contains transition metals, while the f-block consists of the lanthanides and actinides, both based on the electron subshell occupied by their highest energy electrons
Metals, found on the left side of the periodic table, have high melting points, shiny surfaces, and good electrical conductivity
Non-metals, located on the right side of the periodic table, often form negative ions and have varying melting points
Metalloids, positioned between metals and non-metals, exhibit mixed properties of both groups
Early classifications by Döbereiner and Newlands laid the foundation for Dmitri Mendeleev's 1869 table
Mendeleev's periodic table organized elements by atomic mass and successfully predicted undiscovered elements
The modern periodic table, organized by atomic number, reflects the deeper understanding of atomic structure gained in the 20th century