1. how did dmitri mendeleev deal with elements that had not yet been discovered?
a. he left blanks for them in his periodic table, as he predicted they would be discovered.
b. he gave them names and properties and placed them in the table.
c. he created them in his laboratory and placed them in the table.
d. he ignored them, placing them in the table and shifting others when they were discovered. 2. which of the following elements have properties similar to those of astatine (at)? a. f, br, i b. ar, s, p c. f, ar, ne d. na, mg, al 3.what is true of the ionic size of the elements in a group as one moves from top to bottom in that group?
a. ionic size stays the same within the group.
b. ionic size does not vary in any predictable way within the group.
c. ionic size decreases from top to bottom within the group.
d. ionic size increases from top to bottom within the group.