Characteristics of Mendeleev’s periodic table:
  
Answer variants:
elements
atomic mass
atoms
periods
subgroups
properties
unknown
groups
empty
  
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.