WBBSE Class 10 Physical Science Chapter 8.1 Notes in English | WBBSE Class 10 Physical Science Chapter 8.1(Periodic Table) Notes in ENGLISH
WBBSE Class 10 Physical Science Chapter 8.1 Notes in English | Periodic Table and Periodicity of the Properties of Elements
**Very Short Answer Type Questions:**
**1. Periodic Changes:**
- *What undergoes periodic changes in a periodic table?*
- **Answer:** The physical and chemical properties of a group of elements arranged in some way or the other keep changing from time to time..
**2. Atomic Size in a Group:**
- *How does the atomic size of elements change in a group?*
- **Answer:** Atomic size gradually increases downward in a group.
**3. Electronegativity Along a Period:**
- *How does electronegativity of elements change along a period of the periodic table?*
- **Answer:** Electronegativity of elements gradually increases along a period from left to right of the periodic table.
**4. Groups in Long Form Periodic Table:**
- *How many groups are there in the long-form periodic table?*
- **Answer:** There are 18 groups in the long-form periodic table.
**5. Metallic Character in a Group:**
- *How does the metallic character of elements change in a group in the periodic table?*
- **Answer:** Metallic character of elements gradually increases downward in a group.
**6. Fundamental: Atomic Number vs. Atomic Weight:**
- *Which is more fundamental: atomic number or atomic weight of elements?*
- **Answer:** Atomic number is more fundamental than atomic weight of elements.
**7. Elements Arrangement in Mendeleev’s Table:**
- *How are elements arranged in Mendeleev’s modern periodic table?*
- **Answer:** Elements are arranged in Mendeleev’s modern periodic table in ascending order of their atomic number.
**8. Position of Chlorine in Mendeleev’s Table:**
- *What is the position of chlorine in Mendeleev’s periodic table?*
- **Answer:** Period: 3, Group: VIIB
**9. Group of Alkali Metals in Mendeleev’s Table:**
- *In which group of Mendeleev’s periodic table are alkali metals kept?*
- **Answer:** Alkali metals are kept in Group IA in Mendeleev’s periodic table.
**10. Oxygen Group Name:**
- *What is the name of the 'Oxygen' group?*
- **Answer:** Chalcogens.
**11. d-Block Elements:**
- *What are ‘d’-block elements called?*
- **Answer:** 'd block elements are known as transition element
**12. f-Block Elements:**
- *What are ‘f’-block elements called?*
- **Answer:** 'f'-block elements are called inner transition elements.
**13. Elements in First Period of Mendeleev’s Table:**
- *How many elements are there in the first period of Mendeleev’s periodic table?*
- **Answer:** The first period contains two elements (Hydrogen and Helium).
**14. First Group Elements:**
- *What is the name of the first group elements of the periodic table?*
- **Answer:** The first group elements of the periodic table are called alkali metals.
**15. Electron Affinity of F, Cl, Br:**
- *What is the decreasing order of electron affinity of F, Cl, Br?*
- **Answer:** The decreasing order of electron affinity of F, Cl, Br is Cl > Br > F.
**16. Cobalt as a Transition Element:**
- *Is Cobalt a transition element?*
- **Answer:** Yes, Cobalt is a transition element.
**17. Second Ionization Energy:**
- *Is the second I.P. always greater than the first I.P. of a given species?*
- **Answer:** Yes, the second ionization energy is always greater than the first ionization energy of a given species.
**18. Radioactivity as a Periodic Property:**
- *Is radioactivity a periodic property?*
- **Answer:** No, radioactivity is not a periodic property.
**19. Atomic Size Between K and Ca:**
- *Between K and Ca atom, which one has a larger size?*
- **Answer:** K atom has a larger size than Ca atom.
**20. Symbol of Element with Atomic Number 109:**
- *What is the symbol of the element having atomic number 109?*
- **Answer:** The symbol of the element having atomic number 109 is Mt.
**21. Proposer of Modern Periodic Law:**
- *Who proposed the modern periodic law?*
- **Answer:** Modern periodic law was proposed by Mosely.
**22. Representative Elements:**
- *What are representative elements?*
- **Answer:** Elements of s- and p-blocks are collectively known as normal or representative elements.
**23. Elements of Second Period:**
- *What are the elements of the second period called?*
- **Answer:** Elements of the second period are called bridge elements.
**24. Elements of Third Period:**
- *What are the elements of the third period called?*
- **Answer:** Elements of the third period are called typical elements.
**25. Size Between Na and Na^+:**
- *Between Na and Na^+, which one has greater size?*
- **Answer:** Na has a greater size than Na^+.
**26. Size Between Cl and Clθ:**
- *Between Cl and Clθ, which one has smaller size?*
- **Answer:** Cl has a smaller size than Clθ.
**27. Size Between Na^+ and Mg^2+:**
- *Between Na^+ and Mg^2+, which one has smaller size?*
- **Answer:** Mg^2+ has a smaller size than Na^+.
**28. Van der Waal’s Radii vs. Covalent Radii:**
- *Are Van der Waal’s radii larger than covalent radii?*
- **Answer:** Yes, Van der Waal’s radii are larger than covalent radii.
**29. Atomic Radii Across a Period:**
- *Atomic radii decrease across a period. However, at the end of each period, there is an increase in atomic radii. Why?*
- **Answer:** Because atomic radii in the case of noble gases are Van der Waal’s radii.
**30. Sign of Ionisation Energies:**
- *Have ionization energies a positive value?*
- **Answer:** Yes, ionization energies have a positive value.
**31. High Electron Affinity of Halogens:**
- *Why do halogens have high values of electron affinity?*
- **Answer:** Halogens have high values of electron affinity due to their ns² np⁵ configuration.
**32. Classification of Elements:**
- *What is the classification of elements?*
- **Answer:** The method of arranging similar elements together and separating them from dissimilar elements is called the classification of elements.
**33. Law of Triads:**
- *What is the law of triads?*
- **Answer:** According to the law of triads, in a triad of elements with similar properties, the atomic weight of the central atom is the arithmetic mean of the atomic weights of the other two elements.
**34. Metallic Character Between Br and I:**
- *Between Br and I, which one
has metallic character?*
- **Answer:** Between Br and I, iodine has metallic character.
**35. Valency of Alkali Metal:**
- *What is the valency of an alkali metal?*
- **Answer:** The valency of an alkali metal is 1.
**36. Relation Between N³⁻ and O²⁻:**
- *What is the relation between N³⁻ and O²⁻?*
- **Answer:** N³⁻ and O²⁻ are iso-electronic ions.
**37. Radioactive Halogen:**
- *Which halogen is a radioactive element?*
- **Answer:** Astatine (At) is the only radioactive halogen.
**38. Missing Group in Mendeleev’s Table:**
- *Which group of elements was missing from Mendeleev’s original periodic table?*
- **Answer:** Mendeleev’s original periodic table did not contain noble or inert gases belonging to Group 18 of the modern periodic table.
**39. Transitional Elements in First Period:**
- *In which period of the periodic table are first transitional elements found?*
- **Answer:** The first series of transitional elements belong to the 4th period.
**40. Atomic Mass of Element Y in Dobereiner’s Triad:**
- *X, Y, and Z are the elements of a Dobereiner’s triad. If the atomic mass of X is 20 and that of Z is 40, what should be the atomic mass of Y?*
- **Answer:** Atomic mass of Y = Arithmetic mean of atomic masses of X and Z = (20 + 40)/2 = 30
**41. Position of Radioactive Alkali Metal:**
- *Mention the position of the radioactive alkali metal.*
- **Answer:** Francium (Fr), the radioactive alkali metal, has a position in the 1st group of the 7th period.
**42. Lanthanide with Lowest Atomic Number:**
- *Name the lanthanide having the lowest atomic number.*
- **Answer:** Cerium (58Ce) is the lanthanide having the lowest atomic number.
**43. Halogen with Lowest Electronegativity:**
- *Which halogen has the lowest electronegativity?*
- **Answer:** Electronegativity of an atom decreases from top to bottom in a group. Therefore, Astatine (At) has the lowest electronegativity of 2.2 (Pauling scale).
**44. Atomic Number 9 in Modern Periodic Table:**
- *The atomic number of an element is 9. In which group should it be placed in the modern periodic table?*
- **Answer:** The element should be placed in Group 17 since it has 7 electrons in its outermost shell.
**45. Element Not Known in Mendeleev’s Time:**
- *Name one element which was not known during Mendeleev’s time, but a place was left vacant in Mendeleev’s periodic table.*
- **Answer:** The element is Germanium (Ge), which was not known during Mendeleev’s time, but its properties were predicted by Mendeleev, and accordingly, a place was kept vacant for it in his periodic table.
