What is meant by valency? Write the valency of Na, Mg, Ca and Al.

Q. What is meant by valency of elements ?

Q.

Question 17
Arrange the following elements in the order of their decreasing metallic character
Na, Si, Cl, Mg, Al

(a) Cl > Si >Al > Mg >Na
(b) Na >Mg >Al >Si > Cl
(c) Na > Al > Mg > Cl > Si
(d) Al > Na> Si > Ca> Mg

Q. Answer the following
A. Whati is the difference in the atomic models of Thomson and Rutherford ?
B. What is meant by valency of an element ? what is the relationship between the number of valence electron and valency ?
C. What is meant by atomic mass number ? Explain how the atomic number and mass number of carbon are 6 and 12 respectively.
D. what is meant by subatomic particle ? give brief information of three subatomic particles with refrence to electrical charge, mass and location.

Q.

The first ionistation enthalpies of Na, Mg, Al, and Si are in the order
(a) Na< Mg > Al < Si (b) Na> Mg > Al > Si
(c) Na< Mg< Al< Si (d) Na> Mg> Al < Si

Q.

In the formula $CaB{r}_2$​ what does Ca stand for and what is its valency?