Education

Metals and Nonmetals
Education

Metals and Nonmetals

Metals are currently the oldest toxins that are known. Approximately 80 of the 105 elements are known to be metals in the periodic table, although less than 30 have been reported to cause toxicity in humans. As micronutrients, several metals are necessary and play a critical role in tissue metabolism and development. Inhalation through the […]

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Education

Physical Change and Chemical Change

Physical changes are usually easier to reverse than chemical ones. For example, a large piece of paper can be restored by taping or pasting the small pieces of paper together again. Bending, breaking and crushing are other ways to change matter physically. Cutting up a piece of paper is an example of a physical change. […]

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