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עמוד:20
Questions 1 . Find the element magnesium ( Mg ) in the table . What is its atomic number ? 2 . Name another element whose properties are similar to those of magnesium . Explain . 3 . Name an element that belongs to the same period as magnesium in the periodic table . 4 . In the following table fill in the missing details . Enrichment Predicting the properties of elements using the periodic table When Mendeleev arranged the elements in the periodic table , he noticed that in some places there were “ missing” elements . Mendeleev reserved empty slots in the periodic table for these elements , and claimed that they exist but have not yet been discovered . He even calculated the atomic mass of the elements and predicted their properties . Later on it turned out that in most cases he was right . In the figure below present part of Mendeleev’s original periodic table , with an empty slot for an element below aluminum ( in the third column ) . Mendeleev calculated the atomic mass of this element and predicted that its properties would be similar to those of aluminum . When the element was discovered in 1875 , it was named Gallium , and it was found that its properties are indeed similar to those that Mendeleev had predicted .
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