Because back in 1869 they didn't know all of the periods that we know today.
Mendeleev's periodic table arranged elements by increasing atomic mass and grouped elements with similar properties together. Today's periodic table is similar, but it is arranged by increasing atomic number, which reflects the number of protons in an atom's nucleus. Both tables also show periodic trends in properties as you move across and down the table.
There are 91 metals in the periodic table today, but new ones are added as time passes.
The modern periodic table was invented by Dmitri Mendeleev in 1869. Mendeleev organized the elements by increasing atomic mass and grouped them based on similar chemical properties, which laid the foundation for the periodic table we use today.
Dmitri Mendeleev is known as the father of the periodic table. He developed the periodic table by arranging elements based on their atomic mass and chemical properties, establishing the foundation for the modern periodic table used today. Mendeleev's table had gaps for undiscovered elements, which were later found and filled, validating his organization of the elements.
Dmitri Mendeleev's arrangement of elements is called the periodic table. He organized the elements based on their atomic mass and chemical properties, leading to the development of the modern periodic table used today.
Mendeleev's periodic table arranged elements by increasing atomic mass and grouped elements with similar properties together. Today's periodic table is similar, but it is arranged by increasing atomic number, which reflects the number of protons in an atom's nucleus. Both tables also show periodic trends in properties as you move across and down the table.
Dmitri Mendeleev was a Russian chemist who proposed the Periodic Law. He published the first periodic table of the chemical elements in 1869, based on the increasing atomic masses of the different elements.
It looks the same as it did when Mendeleev created it. There are no changes made to the table throughout the years because Mendeleev had predicted the correct placement for all of our current known elements.
Chemists
There are 91 metals in the periodic table today, but new ones are added as time passes.
i don't know the scientist but it is the periodic table of the elements
well every known materialthat we asociate with is listed in the periodic table.
Henry Moseley
Dmitri Mendeleev.
he drew up a table that grouped elements according to their atomic weights, his table became the basis for the periodic table of elements used today.
Hydrogen is the first chemical element in the Periodic Table of Mendeleev.
Henry Moseley in 1914