Mendeleev at the time arranged the elements in order of atomic mass
He organized elements with similar properties in same groups so he left gaps for elements which hadn't been discovered yet
Mendeleev thought he organized elements in order of increasing atomicmass but this wasn't always true because of the relative abundance of istopes of some pairs of elements in the periodic table
The period tells you the number of shells an element has
The group tells you how many electrons is on its outer shell
Dimitri mendeleev did what?
Left gapss for undiscovered elements
Metals can react to form positive ions
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In periodi table what is period arranged as
elements are arranged in order of increasing atomic number, in rows
In periodic table what is groups arranged as
elements with similar properties are placed in the same vertical columns called groups
