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Elements are arranged in the periodic table based on their atomic number, which increases from left to right and top to bottom. Within this arrangement, elements are categorized into groups or families with similar chemical properties. These properties largely depend on the number of electrons in the group shell. For instance, oxygen, sulfur, and selenium belong to the same group, known as oxygen group or chalcogens, because they all have six electrons in their outermost shell.

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The hardness of limestone can vary greatly, from relatively soft to extremely hard, depending on factors such as its mineral content and degree of compaction. Soft limestones can be easily drilled using standard drilling equipment, but harder varieties often necessitate more robust machinery and specialized bits. Carbide-tipped drill bits, for instance, are commonly employed due to their durability and ability to withstand the abrasive nature of limestone.

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{随机栏目} 2025-08-14 10:13 933