Did Dobereiner’s triads also exist in the columns of Newlands’ Octaves ? Compare and find out.
Only one triad of Dobereiner’s triads exists in the columns of Newlands’ octaves. The triad formed by the elements Li, Na, and K of Dobereiner’s triads also occurred in the columns of Newlands’ octaves.
Dobereiner’s triads
$\begin{matrix}
Li & Ca & Cl \\
Na & Sr & Br \\
K & Ba & I \\
\end{matrix}$
Newlands’ octaves
$H$ | $Li$ | $Be$ | $B$ | $C$ | $N$ | $O$ |
$F$ | $Na$ | $Mg$ | $Al$ | $Si$ | $P$ | $S$ |
$Cl$ | $K$ | $Ca$ | $Cr$ | $Ti$ | $Mn$ | $Fe$ |
$Co$ and $Ni$ | $Cu$ | $Zn$ | $Y$ | $In$ | $As$ | $Se$ |
$Br$ | $Rb$ | $Sr$ | $Ce$ and $La$ | $Zr$ | - | - |
Use Mendeléev’s Periodic Table to predict the formulae for the oxides of the following elements :
$K,\, C,\, Al,\, Si,\, Ba$.
The position of three elements $A$, $B$ and $C$ in the Periodic Table are shown below
Group $16$ | Group $17$ |
- | - |
- | $A$ |
- | - |
$B$ | $C$ |
$ (a)$ State whether $A$ is a metal or non-metal.
$(b)$ State whether $C$ is more reactive or less reactive than $A$.
What were the criteria used by Mendeléev in creating his Periodic Table ?
How could the Modern Periodic Table remove various anomalies of Mendeléev’s Periodic Table ?
Nitrogen (atomic number $7$) and phosphorus (atomic number $15$) belong to group $15$ of the Periodic Table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?