Select all the correct answers. Which statements about the structure of the periodic table are true?

The periodic table has an irregular shape because it has more periods than groups.
The inner transition elements are placed at the bottom of the periodic table for easy viewing.
The periodic table has horizontal groups and vertical periods, giving it a regular rectangle shape.
The distribution of electrons in energy levels is responsible for the shape of the periodic table.
Nonmetals take up more than half the area of the periodic table.