The periodic table class 10

if you want any other ppt of any other topic please comment

1. THE PERIODIC TABLE

2. Importance of classification of elements

3. Basis of classification of elements:

4. Dobereiner's law of triads : ’Chemically analogous elements arranged in increasing order of atomic weights formed well marked groups of three called triads in which the atomic weight of the middle element was found to be generally the average of the atomic weights of the other two elements.’

5. Limitations of Dobereiner’s Triads:

6. Newlands law of octaves: When the elements are arranged in increasing order of their atomic masses, the properties of the eighth element are like that of the first.

7. L imitations of Newlands ' law of octaves: It was applicable to only lighter elements having atomic masses up to 40, i.e., up to calcium. After calcium, the first and the eighth element did not have similar properties. It failed to leave spaces for undiscovered elements.

8. Mendeleev’s Periodic law : The Physical and Chemical Properties of the elements are periodic functions of their atomic weights.

9. Mendeleev’s contributions:

10. Defects in Mendeleev’s periodic table:

11. Modern Periodic Law: Moseley modified Mendeleev’s periodic law to form the modern periodic law – The physical and chemical properties of elements are the periodic function of their atomic numbers.

12. Periodicity of elements

13. Salient Features of modern periodic table

14. There are 18 vertical columns in the periodic table called ‘Groups’. 2.There are 18 vertical columns in the periodic table called ‘Groups’. Group 1-alkali metals Group 2- alkaline earth metals Group 3- 12 – transition elements Group 13-16 – post transition elements Group 17 –halogens Group 18 – noble / inert gases. Group 1,2,13,14,15,16,17 – normal elements/representative elements. Group number signifies the number of valence electrons of an element. Elements of the same group have the same number of valence electrons hence same valency and similar properties. Number of electron shells increases by one Metallic character increases down a group.

15. Period in a periodic table

16. Bridge elements They show similarities in properties diagonally with the period of the next group.

17. Group in a periodic table A group (also known as a family) is a column of elements in the periodic table of the chemical elements. There are 18 numbered groups in the periodic table, but the f-block columns (between groups 2 and 3) are not numbered.

18. Property trends – down a sub-group

19. Group IA elements Group VIIA elements Elements Li, Na, K, rubidium, caseium, francium Fl, Cl, Br, I, astatine Valency 1 valence eˉ => Univalent 7 valence eˉ => univalent Nature Highly – reactive and electropositive ; light & soft metals – can be cut with a knife Highly – reactive and electronegative; Non - metals – some are gaseous, liquid and solid at room temp. Conductivity Good Bad or Non - conductors Reducing / oxi- dizing agents Strong reducing agents Strong oxidizing agents Reaction with Nonmetals Electrovalent compounds are formed Covalent compounds are formed Reaction with ‘H’ Ionic hydrides are formed Covalent hydrides are formed

20. Periodicity

21. Atomic radius/size .   Atomic radius: distance between the center of the nucleus and the outermost shell. U nit => A    

22. Factors affecting Atomic radius/size Number of shells increases & atomic size increases Reason – As the No. of shells increases – the distance between the nucleus and the outermost shell increases Nuclear charge increases and atomic size decreases Reason – Nuclear charge increases – the electrons of the outermost shell are attracted with increasing force Nuclear charge is the positive charge of the atom Nuclear charge is equivalent to the atomic number of the element

23. Trends in atomic size – from left to right of a period Number of shells – Remain the same and Atomic Size – Remains unaffected Nuclear charge – Increases and Atomic size – Decreases In Period 2 – Li – largest atomic Radius In period 2 – F - smallest atomic radius Neon has larger atomic radius as its outermost shell is completely filled The effect of nuclear pull over the valence shell electrons is not seen

24. Trends in atomic size; down a group Number of shells increases and atomic size increases Nuclear charge increases and atomic size should decrease Atomic radius/size increases down a group

25. Ionization potential . Ionization potential : amount of energy required to remove an electron from the outermost shell of an isolated gaseous atom. Unit => eV

26. Factors affecting – ionization potential Atomic size increases and Ionization potential – Decreases Reason – Atomic size increases and the nuclear attraction on the outer electron - decreases Outer electrons are loosely held Nuclear charge increases and ionization potential – increases Reason – Nuclear charge increases and the nuclear attraction on the outer electron – increases Outer electrons are tightly held

27. Trends in ionization potential

28. Trends in I.P. – down a group Atomic radius increases and I.P. decreases Nuclear charge – Increases and so I.P. should decrease I.P. decreases down a group

29. Electron Affinity amount of energy released when an atom in the gaseous state accepts an electron to form an anion. Unit is eV

30. Factors affecting electron affinity Atomic size increases and Electron affinity decreases Reason: A small atom takes up electrons more readily than a large atom Because the nucleus has greater attraction on the electrons Nuclear charge increases and electron affinity increases Nuclear charge increases: Similarly increases the tendency of atom to accept electrons

31. Trends in electron affinity – across a period – from left – right Atomic radius decreases and electron affinity increases Nuclear charge increases and electron affinity increases Neon has electron affinity zero as its outermost shells are filled Electron affinity is highest for halogens group 17 and least for alkali metals group 1 More value of electron affinity more is the electronegativity Electron affinity increases across a period from left to right

32. Trends in electron affinity down a group Atomic radius increases and E.A. decreases Nuclear charge – Increases and so E.A. should decrease E.A. decreases down a group

33. Electro - negativity It is the tendency of an atom to attract itself in the gaseous state accepts an electron to form an anion

34. Factors affecting electro-negativity Atomic size increases and electro-negativity decreases. Nuclear charge increases and electronegativity increases Reasons – same as electron affinity

35. Trends in electro-negativity across a period from left to right Atomic radius decreases and electro-negativity increases Nuclear charge increases and electro-negativity increases Elements with high electronegativity are usually non-metallic Fluorine is the most electronegative element and caesium id the least Noble gases have complete octet and so they do not attract electrons electro-negativity increases across a period from left to right

36. Trends in Electro-negativity down a group Atomic radius increases and electro-negativity decreases Nuclear charge increases and electro-negativity should increase Electro-negativity decreases down a group

37. Features of long form of periodic table 1. 18 vertical columns known as groups. 2. 7 Horizontal rows known as periods.  3. Light metals These are elements of periodic table of group 1 and 2. 4. Heavy metals or Transition metals - These are elements of periodic table of group 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12.     5. Non-Metals These are elements of periodic table of group 13, 14, 15, 16 and 17.  6. Zero group These are elements of periodic table of group 18.

38. Metallic and non - metallic character - term Metallic character electro positive Non - Metallic character In terms of electron losing property – an atom is said to be a – Metal , if it loses one or more electrons when supplied with energy. In terms of electron gaining property – an atom is said to be a – Metal , if it gains one or more electrons when supplied with energy.

39. Factors affecting metallic and non- metallic character

40. Trends in character – across a period from left to right Atomic radius decreases and metallic character decreases ; non – metallic character increases I.P. increases and metallic character decreases ; non – metallic character increases Metallic character decreases across a period ; Non – metallic character increases across a period

41. Trends a character down a group

42. Physical properties - density and melting point Across a period – density and & melting points – increase gradually

43. Physical properties - density and melting point and boiling point Down a group density increases gradually & m.p & b.p. of elements decreases gradually

44. Chemical properties – periodicity in properties of compounds of elements Characteristics Varies across a period Varies down a group Oxides Strongly basic to strongly acidic Acidic to Basic Hydroxides Strongly basic to Amphoteric Less basic to Strongly basic Oxy-acids Weak oxy-acids to Strong oxy-acids Strong oxy-acids to Weak oxy-acids Hydrides Strongly basic to strongly acidic Less Acidic to More Acidic

45. Stable and unstable elements

46. Modern Periodic Table

47. About There are 18 vertical columns in the periodic table. Each column is called a group. All elements in a group have similar chemical and physical properties because they have the same number of outer electrons.  In periodic table elements are arranged in a series of rows. Elements of the same period have the same number of electron shells.

48. Modern Periodic Law The properties of elements are the periodic function of their atomic number i.e. number of protons.

49. Position of Elements in the Periodic Table

50. Location of Metals, Non-metals, Metalloids and Noble Gases are as follows:

51. Periodic Table Chart The  Periodic Table  organizes the elements according to their similar chemical and physical properties. The Table has rows and columns. The vertical columns in the periodic table represent  Groups . The horizontal rows in table represents  Periods .

52. Determine the period number of elements All the elements in a period have the same number of atomic orbitals. For example, every element in the top row (the first period) has one orbital for its electrons. All the elements in the second row (the second period) have two orbitals for their electrons.

53. Determine the group number of elements The group number is an identifier used to describe the column of the standard periodic table in which the element appears. Groups 1-2 (except hydrogen) and 13-18 are termed main group elements. Groups 3-11 are termed transition elements. Electronic configuration of Sodium is 2, 8, 1. So the number of group is 1

54. Occurrence of alkali earth metals Alkaline earth metals are obtained in the form of their ore in earth's crust. Of the alkaline earth metals calcium and magnesium rank fifth and sixth in abundance respectively, in earth crust. Beryllium is rare and radium is rarest of all.

55. CHARACTERISTICS Alkali metals are highly reactive elements. They are soft, have low density, low melting point, low boiling point, give characteristic color to the flame, are strongly electro-positive character. They react with water liberating H2 and react with acids replacing hydrogen.

56. NOBLE GASES