organizing element

_______is the average mass of all the isotopes of the element .

• atomic number

• atomic mass

__________the number of protons

• mass number

• atomic number

• atomic mass

Mendeleev noticed that a pattern of properties appeared when he arranged the elements in order of_______________

• increasing atomic mass

• decreasing atomic mass

why Mendeleev left space in his periodic table ?

• to make it bigger

• because he predicted that these spaces would be filled by elements that had not yet been discovered.

The modern periodic table is arranged according to increasing _________

• atomic mass

• atomic number

__________is an abbreviation of an element’s name. It contains either one or two letters.

• Chemical reaction

• chemical symbol

The periodic table is made up of rows called __________

• periods

• groups

There are____________________in the periodic table

• seven periods and 18 groups

• 8 periods and 18 groups

Metals are shown on the______

• left

• right

Nonmetals are shown on the______

• left

• right