I am pretty sure it is the weight of the element, but do not quote me on that. Google it!
I believe they use an advanced form of Dmitri Mendeleev's pattern for organizing and estimating elements.
Atomic mass of an atom can be known by the total number of neutrons and protons
The Atomic Mass of an element using the Periodic Table can be determined by the number beneath the element abbreviation. It is usually in the decimal form.
Follow the link below.
6 is the atomic mass number of an element
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Mendeleev arranged elements in rows and columns according to increasing atomic masses. The elements with same properties were grouped together which formed the base for modern periodic table.
He arranged the elements in the increasing order of their atomic masses and repeating periodic properties.
In the first Periodic Table by Mendeleev, he arranged the elements in the increasing order of their atomic masses and repeating properties.
The physical and chemical properties of the elements are periodic functions of their atomic numbers.The periodic law states that the physical and chemical properties of elements are periodic functions of their atomic numbers. They influence the characters of an element more than atomic weight.
Mandeleev who predicted periodic table.
Mendeleev arranged elements in rows and columns according to increasing atomic masses. The elements with same properties were grouped together which formed the base for modern periodic table.
He arranged the elements in the increasing order of their atomic masses and repeating periodic properties.
Properties of elements are a periodic function of their atomic masses.
In the first Periodic Table by Mendeleev, he arranged the elements in the increasing order of their atomic masses and repeating properties.
increasing atomic number and repeating properties
in order of their reletive atomic masses
Each element has its own atomic mass.
Mendeleev's periodic law states that "Properties of elements are periodic function of their atomic masses".
Atomic masses are determined by mass spectrometry. The atomic number is identic with the number of protons in the atom - depends on position in the periodic table.
Mendeleev arranged elements in his periodic table on the basis of increasing atomic masses.
Dmitiri Mendeleev arranged the Periodic Table of elements in order of increasing atomic masses.
Mendeleev arranged the elements in a table in the increasing order of atomic masses and repeating periodic properties. In the modern long-form of periodic table, the elements are arranged in the increasing order of atomic number and repeating periodic properties.