Its about Mendeleev and his contribution to the modern periodic table. It also discusses about the advantages and disadvantages of his periodic table. it also has about eka-aluminium which is gallium.

1. Done by:
Mohit Raj Bhurat
X B

2. 8 February 1834 – 2 February 1907 was a Russian chemist and
inventor. He formulated the Periodic Law, created a farsighted
version of the periodic table of elements, and used it to correct
the properties of some already discovered elements and also to
predict the properties of eight elements yet to be discovered.

3. In 1863 there were 56 known elements with a new element
being discovered at a rate of approximately one per year.
Other scientists had previously identified periodicity of
elements. John Newlands described a Law of Octaves,
noting their periodicity according to relative atomic weight
in 1864, publishing it in 1865. His proposal identified the
potential for new elements such as germanium. The concept
was criticized and his innovation was not recognized by the
Society of Chemists until 1887. Another person to propose a
periodic table was Lothar Meyer, who published a paper in
1864 describing 28 elements classified by their valence, but
with no prediction of new elements.

4. Mendeleev becoming a teacher in 1867, Mendeleev wrote the
definitive textbook of his time: Principles of Chemistry (two
volumes, 1868–1870). It was written as he was preparing a textbook
for his course. This is when he made his most important
discovery. As he attempted to classify the elements according to
their chemical properties, he noticed patterns that led him to
postulate his periodic table; he claimed to have envisioned the
complete arrangement of the elements in a dream.
"I saw in a dream a table where all elements fell into place as
required. Awakening, I immediately wrote it down on a piece of
paper, only in one place did a correction later seem necessary."
— Mendeleev,

5. Is it because he listed down the
known elements ?
Nah! Besides he wasn’t even
the first person to do it.
Is it because he arranged
elements with similar
properties together ?
No! that had also already
been done too.

6. Mendeleev’s periodic table is mainly based on two
facts:-
i. Atomic mass
ii. Similarity of chemical properties
Mendeleev’s periodic law:
“The physical and chemical properties of
elements are the periodic functions of their
atomic masses.”

7. If you observe the 3rd column and 5th row you will observe a dash. That
dash there proves his genius.
He made a very bold statement here :
“We all haven't discovered this element yet, in the meantime I am
going to give it a name. it is one step from aluminum so I will call it
eka- aluminum” – Mendeleev.(Eka being one in Sanskrit.)

8. “Nobody found eka-aluminum yet so we don’t know
anything about it right? Wrong. Based on where it is
located I can tell you all about it.” said Mendeleev. Later he
made a few conclusions about eka-aluminum. He said
 Atomic weight 68
 Solid metal
 Lustrous
 Heat conductivity
 Malleable & Ductile
 Melting point low
 Cubic cm weighs 6g.

9. He basically arranged the elements according to their masses but
sometimes placed a lighter element before a heavier one to satisfy that all
elements in the column have similar properties.
Example : In reality Nickel weighs less than cobalt but Mendeleev has
placed cobalt before nickel.

10. a. Position oh hydrogen
Hydrogen has been placed with in 1st group with the alkali
metals. Hydrogen makes compound just like the alkali
metals but also exist as diatomic molecule like halogens.
Mendeleev could not explain about this anomaly.
b. Isotopes
Mendeleev could not give separate position for the
isotope of a elements.