periodic table Flashcards
1
Q
who made the first periodic table?
A
mendeléev
2
Q
how to we organize the elements?
A
in rows by increasing atomic number
3
Q
what is another name for the horizontal rows
A
periods
4
Q
how are periods labeled
A
1-7
5
Q
what is another name for the vertical columns?
A
groups
6
Q
how are groups labeled?
A
1-18
7
Q
how many elements are there?
A
118
8
Q
how many elements are naturally occurring?
A
98
9
Q
how many elements are human made?
A
20
