Q: Mendeleev organized what basic units into rows and columns?


Read this paragraph and choose the correct option from the provided answers:

You can see how Mendeleev organized the elements in the Figure below . From left to right across each row, elements are arranged by increasing atomic mass. Mendeleev discovered that if he placed eight elements in each row and then continued on to the next row, the columns of the table would contain elements with similar properties. He called the columns groups . They are sometimes called families, because elements within a group are similar but not identical to one another, like people in a family.

 Choices:

- solutions

- compounds

- animals

- elements


A:
elements