STRUCTURE OF THE ATOM

STRUCTURE OF THE ATOM

VERY SHORT ANSWER TYPE QUESTIONS (VSAQ)

1. What charge do electrons have? Ans :- Electrons have a negative charge. 2. Why is an atom considered electricall...

11. What did J.J. Thomson propose about the structure of an atom? Ans :- He proposed that an atom is like a Christma...

21. If an atom contains one electron and one proton, will it carry any charge or not? Ans :- It will not carry any...

31. Why did Rutherford select a gold foil in his a-ray scattering experiment? Ans :- Rutherford chose gold foil for...

41. Why noble gases show least reactivity? Ans :- Noble gases have their outermost octet completely filled up, so t...

51. Why is an atom electrically neutral? Ans :- It has same number of protons and electrons, (positive charge = neg...

SHORT ANSWER TYPE QUESTIONS (SAQ)

1. What happens when you rub two objects together? Ans :- When you rub two objects together, they become electricall...

2. What did J.J. Thomson discover about the atom? Ans :- J.J. Thomson discovered that atoms contain tiny negatively...

3. What are ions? What are its two types? Ans :- When one or more electrons are removed from a neutral atom, it bec...

4. What happens to the nucleus of an atom when it emits a γ− ray? Ans :- When a nuclide emits a γ-ray, its mass and...

5. State Mendeleev’s periodic law? Ans :- Mendeleev’s periodic law states that the properties of elements are perio...

6. Number of protons and electrons are same in an atom. Then why is it wrong to say that atomic number of an atom is equ...

7. If K and L shells of an atom are full, then what would be the total number of electrons in the atom? Ans :- K sh...

8. What is the limitation of J.J. Thomson’s model of an atom? Ans :- The main problem with J.J. Thomson's model is...

9. Why do some elements possess fractional atomic mass? Ans :- Some elements have a fractional atomic mass because...

10. What did E. Goldstein find, and what did it lead to? Ans :- E. Goldstein discovered canal rays, which are positi...

11. What is Thomson's model of the atom compared to, and what does this comparison illustrate? Ans :- Thomson’s mode...

12. How are the positive and negative charges arranged in Thomson's model, and what does this mean for the atom? Ans :...

13. What limitations did Thomson's model have, and how did this affect its acceptance? Ans :- Although Thomson’s mod...

14. What recognition did J.J. Thomson receive for his work, and why is it significant? Ans :- J.J. Thomson was award...

15. What is the main idea behind the "plum pudding model," and how did it contribute to atomic theory? Ans :- The "p...

16. What were the key findings from Rutherford’s experiment with α-particles and gold foil? Ans :- Rutherford found...

17. How did Rutherford explain the structure of the atom based on his observations? Ans :- Rutherford concluded that...

18. What limitations did Rutherford’s model of the atom have? Ans :- Rutherford’s model suggested that electrons mov...

19. What are the main rules for distributing electrons in atomic shells? Ans :- The main rules include that each she...

20. How do you calculate the maximum number of electrons in a shell? Ans :- To calculate the maximum number of elect...

21. Why is the outermost shell limited to 8 electrons? Ans :- The outermost shell is limited to 8 electrons due to t...

22. What does it mean for electrons to fill shells in a specific order? Ans :- Filling shells in a specific order me...

23. How do Bohr and Bury's rules help us understand atomic structure? Ans :- Bohr and Bury's rules help us understan...

24. If number of electrons in an atom is 8 and number of protons is also 8, then (a) What is the atomic number of the a...

25. On the basis of Thomson’s model of an atom, explain how the atom is neutral as a whole. Ans :- According to Tho...

26. An atom is electrically neutral, on loss or gain of electrons why does it become charged? Ans :- An atom is ele...

27. In the structure of an atom why are protons present in the centre and are not pulled outside by the electrons as bot...

28. Helium atom has an atomic mass of 4 u and two protons in its nucleus. How many neutrons does it have? Ans :- Th...

29. Write the distribution of electrons in carbon and sodium atoms. Ans :- The atomic number of carbon is 6, so th...

30. With the help of Table 4.1, find out the mass number of oxygen and Sulphur atoms. Ans :- The mass number of an...

31. Na+ has completely filled K and L shells. Explain. Ans :- Sodium (Na) has an atomic number of 11, so its electr...

32. How can one conclude that electrons are fundamental particles? Ans :- The e/m ratio of electrons remains the sa...

33. Define ionization energy and electron affinity? Ans :- Ionization energy is the amount of energy required to re...

34. Find the valency of 14N 7 and 35Cl17 Ans :- The atomic number of nitrogen = 7, No. of protons = 7, No. of elect...

35. What are the advantages of the Periodic Table? Ans :- In the periodic table, elements are arranged in a tabular...

36. According to you, among the structure of atom studied which model is correct and why? Ans :- Bohr’s model of th...

37. What are the limitations of Rutherford’s model of the atom? Ans :- Rutherford’s model of the atom failed to exp...

38. Define valency by taking examples of silicon and oxygen. Ans :- The valency of an atom is determined by the ele...

39. Write an experiment to show cathode rays are deflected by magnetic fields? Ans :- The experiment to demonstrate...

40. Write the postulates of Bohr theory? Ans :- The postulates of Bohr’s theory are as follows: i. An electron revo...

41. Explain the variation of atomic radius along a period and down a group. Ans :- The atomic radius of an atom in...

42. Why metals are electropositive and non-metals are electronegative in nature? Ans :- Metals are electropositive...

43. What is an octet? Why would atoms want to complete their octet? Ans :- When the outermost shell of an atom—spe...

45. How can an atom become stable by losing or gaining electrons? Ans :- For an atom to be stable, it must have eit...

46. What is the relation between physical and chemical properties of isobars? Ans :- Isobars have different atomic...

LONG ANSWER TYPE QUESTIONS (LAQ)

1. What happens when two objects are rubbed together, and how does this relate to the structure of atoms? Ans :- Whe...

2. Give the number of electron, proton and neutron in 59CO27 and 108Ag47. Ans :- (i) Number of protons in Co = 27...

3. Explain Thomson's model of the atom and its significance in understanding atomic structure. Ans :- J.J. Thomson’s...

4. Discuss the contributions of J.J. Thomson to atomic theory and the implications of his discoveries. Ans :- J.J. T...

5. Explain Rutherford’s atomic model. Ans :- Rutherford proposed a model of the atom based on the alpha particle sc...

6. What were the main contributions of Rutherford's experiment to our understanding of atomic structure, and what limita...

7. What is the significance of the formula 2n2 in determining the number of electrons in atomic shells? Ans :- The...

8. Explain the concept of the octet rule and its importance in atomic structure. Ans :- The octet rule states that t...

9. How was the neutron discovered? Ans :- Until 1920, atoms were thought to consist only of electrons and protons,...

10. How do Bohr and Bury's rules influence our understanding of chemical bonding? Ans :- Bohr and Bury's rules influ...

11. Give the postulates of Dalton’s atomic theory. Ans :- (i) Every element is made up of extremely small particles...

12. Give reasons : (i) Mass number of an atom excludes the mass of an electron. (ii) Nucleus of an atom is charged. (iii...

13. Elaborate the postulates put forward by E. Rutherford about the structure of atom based on the a -particle scatterin...

14. Why is atomic number is more important than atomic weight in predicting the chemical properties of elements? Ans...

SUMMARY

Introduction In Chapter 3, we begin to explore the basic building blocks of matter—atoms and molecules. Different typ...

Charged Particles in Matter Let’s start by doing a couple of easy activities to see how objects get charged: i. Comb y...

The Structure of an Atom Dalton’s atomic theory taught us that atoms were indivisible and indestructible. However, the...

Thomson’s Model of an Atom (Plum Pudding Model) J.J. Thomson proposed a simple model to explain the structure of an ato...

Rutherford’s Model of an Atom Ernest Rutherford wanted to learn how electrons are arranged in an atom. To find out, he...

Bohr’s Model of the Atom To address the issues with Rutherford’s model, Niels Bohr proposed a new understanding of atomi...

How Electrons Are Distributed in Different Orbits (Shells) The way electrons are arranged in an atom was explained by s...

Valency Atoms have tiny particles called electrons that move around the center (nucleus) of the atom in layers called s...

Atomic Number The atomic number of an atom tells us how many protons are inside the nucleus (the center) of that atom....

Mass Number The mass number of an atom tells us how much the atom weighs based on the particles in its nucleus. The ma...

Isotopes Isotopes are atoms of the same element that have the same number of protons (same atomic number) but different...

Isobars Isobars are atoms of different elements that have different atomic numbers (different number of protons) but th...