Question

Valencies of first 20 elements​

Answer 1

1,0,1,2,3,4,3,2,1,0,1,2,3,4,3.5,2,1,0

Answer 2

Valencies of first 30 elements

$\begin{gathered}\begin{array}{| c | c | c |}\hline\bf Atomic\:No. & \bf Elements & \bf Valency \\ \hline1 &\sf Hydrogen & 1 \\ \hline 2 &\sf Helium & 0 \\ \hline 3 &\sf Lithium & 1 \\ \hline 4 &\sf Berrylium & 2 \\ \hline 5 &\sf Boron & 3 \\ \hline 6 &\sf Carbon & 4 \\ \hline 7 &\sf Nitrogen & 3 \\ \hline 8 &\sf Oxygen & 2 \\ \hline 9 &\sf Flourine & 1 \\ \hline 10 &\sf Neon & 0 \\ \hline 11 &\sf Sodium & 1 \\ \hline 12 &\sf Magnesium & 2 \\ \hline13 &\sf Aluminium & 3 \\ \hline 14 &\sf Silicon & 4 \\ \hline 15 &\sf Phosphorus & 3 \\ \hline 16 &\sf Sulphur & 2 \\ \hline 17 &\sf Chlorine & 1 \\ \hline 18 &\sf Argon & 0 \\ \hline 19 &\sf Potassium & 1 \\ \hline 20 &\sf Calcium & 2 \\ \hline 21 &\sf Scandium & 3 \\ \hline 22 &\sf Titanium & 4 \\ \hline 23 &\sf Vanadium & 5,4 \\ \hline 24 &\sf Chromium & 2 \\ \hline 25 &\sf Manganese & 7,4,2 \\ \hline 26 &\sf Iron & 2,3 \\ \hline 27 &\sf Nickel & 3,2 \\ \hline 28 &\sf Cobalt & 2 \\ \hline 29 &\sf Copper & 2,1 \\ \hline 30 &\sf Zinc & 2 \\ \hline\end{array}\end{gathered} \\ \rule{300pt}{8pt}$