Variation of Valency

Q.

Why is the valency of iron is 2 and 3 ..?

Q.

Define valency. How is it calculated for various elements?

Q.

Valencies of all elements

Q. How to find the position of the elements in the modern periodic table

Q.

How does the valency of elements change on moving from left to right in the third period of the periodic table?

Q.

How does the number of valence electrons vary on moving from left to right :

(i) in the first period of the periodic table ? (ii) in the second period of the periodic table ?

Q.

Which of the following elements would lose an electron easily?

(a) Mg (b) Na (c) K (d) Ca

Q.

Calculate the valency of:

$\mathrm{Mn}$ in ${\mathrm{MnO}}_2$

Q. The number of protons is always the number of electrons in a neutral atom.

1. more than
2. less than
3. equal to

Q.

How does the valency of elements vary in going down a group of the periodic table ?

Q. To which period number of the table, do Zinc belong? (Atomic number of zinc is 30).

1. 2
2. 1
3. 7
4. 4

Q.

Question 9
In the modern periodic table, calcium (atomic number 20) is surrounded by elements with atomic numbers 12, 19, 21, and 38. Which of these have physical and chemical properties resembling calcium?

Q. 25.Why the electron gain enthalpy of Neon is more positive than helium as well as other noble gases?

Q. Element 'X' reacts with chlorine to form a chloride compound of formula ${\text{XCl}}_4$. 'X' would most likely belong to the same group in the periodic table as that of:

1. silicon
2. magnesium
3. aluminium
4. sodium

Q. How does an atom attain stability?

1. By having only Helium gas configuration
2. By having total 10 electrons
3. By attaining noble gas configuration.
4. By having incompletely filled shells.

Q.

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

Q. Choose the correct answer:
Among the period 2 elements the one which has high electron affinity is:
(a) Lithium
(b) Carbon
(c) Fluorine
(d) Neon

Q.

Which one of the following does not increase while moving down the group of the periodic table?

1. Atomic radius

2. Metallic character

3. Valence electrons

4. Number of shells in an element

Q. What is valency? Write valency of hydrogen.

Q. An element has an atomic number 16. State:
(i) the period to which it belongs.
(ii) the number of valence electrons.
(iii) whether it is a metal or non-metal.

Q.

Element ‘A’ and B both have atomic numbers 18 and 16 which of respectively. Which of these two would be more reactive and why?

Q.

What are the valencies of Sulfite, Bisulfite, and Sulfate?

Q.

The element which accepts electrons readily to form anion belongs to

1. VII A group and second period

2. VII A group and third period

3. O group and third period

4. VIA group and third period

Q. What is the valency of the group 2 and group 17 elements, respectively? [2 mark]

Q.

Explain why the number of atoms in one mole of hydrogen gas is double the number of atoms in one mole of helium gas?

Q. A _______ is formed when an atom donates its valence electrons.

1. anion
2. compound
3. molecule
4. cation

Q.

Five elements A, B, C, D and E have atomic numbers of 2, 3, 7, 10 and 18 respectively. The elements which belong to the same period of the periodic table are :

(a) A, B, C (b) B, C, D (c) A, D, E (d) B, D, E

Q.

Which one of the following does not increase while moving down the group of the periodic table?

(a) atomic radius (b) metallic character (c) valence electrons (d) shells in the atoms

Q.

Define the following terms with examples: Trivalent

Q.

On moving down in a particular group of modern periodic table the number of valence electrons in the elements______.

1. decreases

2. remains same

3. none of the given option is correct

4. increases