Features of Mendeleev’s periodic table:
Answer variants:
empty
properties
atomic mass
elements
periods
groups
unknown
subgroups
known
1. Mendeleev classified periodic table into seven horizontal rows (called ) and eight vertical (columns called ).
2. Each group divided into two .
3. The first time the elements with similar are grouped.
4. Scientists found certain to be unable to be placed in their proper groups in this manner. Due to their wrong value, a later table will resolve it.
5. Columns were left to accommodate elements that were at the time, and their properties were expected as well.