1. Home Presented By PRAMOD ANANDRAO KONDALKAR ASST. TEACHER ADARSH KISAN VIDYALAYA, NARANDA Back Nextcontent

2. Back Moseley showed that the atomic number of an element is equal to the number of protons in the nucleus of the atom. 1) Moseleys contribution to the classification of elements. He suggested that atomic number should be considered as a more fundamental property of an elements rather than its atomic weight. 2) In modern periodic table, on the basis of Moseleys work, elements were arranged in the increasing order of their atomic number (Z) in a more systematic way. 3) Electronic configuration of an element is directly related to its atomic number (Z). 4) Modern periodic law Law : The properties of the element are the periodic function of their atomic numbers. (Atomic No (Z) is the number of protons in the nucleus or the number of extra nuclear electrons present in the neutral atoms of the elements. ) Nextcontent 3. Modern Periodic Table Home Back Nextcontent 4. Number of Energy Levels: 3 First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 1 Isotopes Home Back Nextcontent Remember The position of an element in the periodic table is generally determined by its electronic configuration. e.g. electronic configuration of sodium is 2, 8, 1 i.e., it has three shells and one electron in the outermost shell. Hence, it is placed in period number 3 and group number 1. However, in the case of transition elements this pattern is not followed. 5. Sketch of the Modern Periodic Table. IIIB VI PERIOD IA IIA IIIB IVB VB VIB VIIB ----VIIIB--- - IB IIB IIIA IVA VA VIA VIIA VIII A/ 0 GR OU P IIIB VII PERIOD Home Back Nextcontent 6. Normal elements Classification of Element 1) The elements of the atoms of which only the outermost shell incompletely filled are called normal elements. 2) The elements of s-block and p-block together, except zero group constitute normal elements. 3) They are reactive elements. 4) They are solids, liquids and gases. 5) Alkali metals, alkaline earth metals and halogensare some of normal elements. Examples : 1) Typical elements : Li, Be, B, C, N, O, F. 2) Representative elements : Na, Mg, Al, Si, P, S, Cl. Home Back Nextcontent 7. Transition Elements 1) The elements of the atoms of which the last two shells incompletely filled are called Transition elements. 2) They are placed in between elements of s-block and p-block. They are also called d-block elements. 3) They belong to group IB to VIIB and VIII. 4) These elements are solid metals at room temperature. Exemple : Cu, Ag, Au, Fe etc. Home Back Nextcontent 8. Inner transition elements 1) The elements of the atoms of which the last three shells incompletely filled are called inner transition elements. 2) They are placed into two separate series at the bottom of periodic table. That series are called Lanthanides series and Actinides series. Each series contain 14 elements. 3) They are also called f-block elements. 4) The elements belonging to each series have quite similar properties. Home Back Nextcontent 9. Inert gases 1) The elements of the atoms of which all shells completely filled are called inert gases or noble gases or rare gases. 2) In the modern periodic table they are placed in zero group. 3) Under ordinary condition these elements are chemically inert due to their stable electronic configuration. 4) They all are gases elements. Example : Helium(He), Neon(Ne), Argon(Ar), Krypton(Kr), Xenon(Xe) and Radon(Rn) are inert gases. Helium (He) Atom Neon (Ne) Atom Home Back Nextcontent 10. Main Features of the Long form of the Periodic Table. Home Back Next 1) The position of an element in the longform of the periodic table is related to its electronic configuration. 2) The number of electronic shells present in the atoms of elements in each period is equal to the number of the period. 3) The number of electrons in the outermost shell of an atom of an element is equal to the group number of the element. 4) Each period begins with an alkali metal element with only one electron is the outermost shell and ends with an inert gas elements having stable electronic configuration i.e. 8 electron in outermost shell. 5) Systematic classification of elements into s-block, p-block, d-block and f- block is achieve in the table. 6) Elements belonging to the same group have the same characteristic electronic configuration in their outermost shell. Hence they show similar chemical properties. 7) Properties of the elements belonging to the same period change gradually from left to right. 8) Metals and non-metals are properly separated in the periodic table. 9) On the basis of electronic configuration elements are classified into inert gases, normal elements, transition elements and inner transition elements. content 11. The elements first period/ second period/ third period of the modern periodic table and their electronic configuration. Elements in first period Electronic Configuration Hydrogen (H) Helium (He) (1) (2) The elements in the first period and their electronic configuration are as follows : Dmitri Mendeleev, father of the periodic tableHydrogen (H) Atom Helium (He) Atom Proton (+) Neutron (no charge) Electron (-) Home Back Nextcontent 12. The elements in the Second period and their electronic configuration are as follows : Elements in Second period Electronic Configuration Lithium (Li) (2,1) Beryllium (Be) (2, 2) Boron (B) (2, 3) Carbon (C) (2, 4) Nitrogen (N) (2, 5) Oxygen (O) (2, 6) Fluorine (F) (2, 7) Neon (Ne) (2, 8) Lithuum (Li) Atom Beryllium (Be) Atom Proton (+) Neutron (no charge) Electron (-) Boron (B) Atom Caron (C) Atom Atomic Structure Home Back Nextcontent 13. The elements in the Third period and their electronic configuration are as follows : Elements in Third period Electronic Configuration Sodium (Na) (2,8, 1) Magnesium (Mg) (2, 8, 2) Aluminium (Al) (2, 8, 3) Silicon (Si) (2, 8, 4) Phosphorus (P) (2, 8, 5) Sulphur (S) (2, 8, 6) Chlorine (Cl) (2, 8, 7) Argon (Ar) (2, 8, 8) Proton (+) Neutron (no charge) Electron (-) Magnesium (Mg) Atom Sodium (Na) Atom Home Back Nextcontent 14. The periods in the modern periodic table. There are 7 periods in the modern periodic table, they are described below. 1) First period is the shortest period containing only two elements hydrogen and helium. 2) Second and third periods known as short periods consist of eight elements each. Second period start lithium and ends with neon and third period start with sodium and ends with argon. Both period contain normal elements. 3) Fourth and fifth periods are long periods containing 18 elements. Fourth period starts with Potassium and ends with krypton. Fifth period start with rubidium and ends with xenon. Each of these periods contains one set of eight normal elements and a set of 10 transition elements. 4) Sixth period is the longest period containing 32 elements from caesium to radon. This period contains 14 lanthanide elements. It includes eight normal elements, 10 transition elements and 14 inner transition elements 5) Seventh period is an incomplete period containing 30 elements (Fr-87 to element-116).It contains 14 inner transition series of actinide elements. Elements coming after uranium are known as transuranic elements. All actinides are radioactive. The elements up to atomic number 92 occur in nature and elements after this are all prepared artificially. Home Back Nextcontent 15. The trends in the valences of the elements in a period. The valency of an elements is the number of hydrogen atoms it can combine with or replace. It related to the number of valence electrons in the atoms of an elements. Group IA IIA IIIA IVA VA VIA VIIA Zero Group Element Li Be B C N O F Ne Chloride LiCl BeCl2 BCl3 CCl4 NCl3 Cl2O ClF No chloride Oxide Li2O BeO B2O3 CO2 N2O3 O2 OF2 No Oxide Hydride LiH BeH2 B2H6 CH4 NH3 H2O HF No Hydride Valency 1 2 3 4 3 2 1 0 2) In a second period, the valency of elements increases from 1 for alkali metals to 4 for the group IVA(14) elements and then decreases to 1 for Halogens VIIA (17), and zero of zero group. Q1) What is the valency of the atom shown in figure? Q2) In which period and which group the atom shown in figure is placed? Home Back Nextcontent 16. Groups of the modern periodic table with reference to the properties of the Elements. There are 18 vertical columns constitute 16 group. These groups are IA - VIIA (1, 2 and 13 - 17), IB - VIIB and the group VIII (3 to 12). 1) 2) Elements belonging to same group have the same numbers of electron in outermost orbit (valence electron). Hence show similar chemical properties. In a group, as atomic number increases new shell are successively added. The atomic size (atomic radius) thus increases and hence shows gradation of properties of the element down the group. 3) Home Back Next content 17. Elements and their Electronic Configuration of the Group IA and their valency. In the atoms of elements of Group IA, only the outermost shell is incomplete with one electron. The elements of group IA (1), have one electron in the valence shell. They are mono valent. Valency : Valency : Group IA (1) elements known as alkali metalsGroup IA (1) elements known as alkali metals Group IA (1) elements are called alkali metals because their oxides are water soluble and they form strong bases, when dissolved in water. Home Back Next Element Atomic Electronic configuration Valency Formula of oxide Formula of number hydroxide Lithium 3 2, 1 +1 Li2O LiOH Sodium 11 2, 8, 1 +1 Na2O NaOH Potassium 19 2, 8, 8, 1 +1 K2O KOH Rubidium 37 2, 8, 18, 8, 1 +1 Rb2O RbOH Caesium 55 2, 8, 18, 18, 8, 1 +1 Cs2O CsOH Francium 87 2, 8, 18, 32, 18, 8, 1 +1 - - content 18. The similarities in the chemical properties of the compounds of alkali metals. 1) The similarities in the chemical properties of (Group IA) alkali metals can be seen from similarity of the molecular formulae of their compounds, and the reaction of water on their chlorides and oxides. Alkali metalsAlkali metals ChloridesChlorides OxideOxide Lithium (Li) Sodium (Na) Potassium (K) LiCl NaCl KCl Li2O Na2O K2O 2) The chlorides and oxides of alkali metal are water soluble and they form strong bases. Exp. NaCl + H2O NaOH + HCl Na2O + H2O 2NaOH Comparison of the reactivity's of sodium (Na), Lithium (Li) and Potassium (K) with respect to reaction with water. Comparison of the reactivity's of sodium (Na), Lithium (Li) and Potassium (K) with respect to reaction with water. As the atomic number increases from Lithium (Li) to Potassium (K), the reactivity also increases. Thus, Lithium (Li) reacts quietly with water, while sodium reacts vigorously with water and the amount of energy released in the reaction is also high that the liberated hydrogen catches fire. 2Na(s) + 2H2O(l) 2NaOH (aq) + H2 + energy 2K(s) + 2H2O(l) 2KOH (aq) + H2 + energy Thus, sodium is more reactive than lithium, while potassium is more reactive than sodium. Home Back Nextcontent 19. Elements of group IIA and their atomic numbers and electronic configuration. Group IIA consists of alkaline earth metals, they are as follows with their atomic numbers and their electronic configuration. Group IIA Elements Z Electronic configuration Beryllium (Be) Magnesium (Mg) Calcium (Ca) Strontium (Sr) Barium (Ba) Radium (Ra) 4 12 20 38 56 88 2,2 2, 8, 2 2, 8, 8, 2 2, 8, 18, 8, 2 2, 8, 18, 18, 8, 2 2, 8, 18, 32, 18, 8, 2 In the atoms of elements of Group IIA, only the outermost shell is incomplete with two electron. Beryllium (Be) Atom Magnesium (Mg) Atom Valency : In the elements of Group IIA , have 2 electrons in their valence shell, hence they are divalent. Exp. MgH2, CaH2 Home Back Nextcontent 20. CaCl2 + 2H2O Ca(OH)2 + 2HClCaCl2 + 2H2O Ca(OH)2 + 2HCl MgCl2 + 2H2O Mg(OH)2 + 2HClMgCl2 + 2H2O Mg(OH)2 + 2HCl The similarities in the chemical properties of the compounds of Alkaline earth metals. 1) Similarities in the chemical properties of (Group IIA) alkaline earth metals can be seen from the similarity of molecular formulae of their compounds. Chlorides of alkaline earth metals Oxides of alkaline earth metals Carbonates of alkaline earth metals BeCl2 MgCl2 CaCl2 BeO MgO CaO BeCO3 MgCO3 CaCO3 2) The chlorides and oxides of alkaline earth metals react with water to give hydroxides. Examples : MgO + 2H2O Mg(OH)2 MgO + 2H2O Mg(OH)2 CaO + 2H2O Ca(OH)2 CaO + 2H2O Ca(OH)2 3) The carbonate of alkaline earth metals lose carbon dioxide on heating and form corresponding oxides Exp: MgCO3(s) MgO(s) + CO2 MgCO3(s) MgO(s) + CO2 heat CaCO3(s) CaO(s) + CO2 CaCO3(s) CaO(s) + CO2 heat Home Back Nextcontent 21. The elements placed in group 7 (VIIA) of the periodic table are called halogens or salt producers. All these elements form salts called halides, e.g. NaCl, NaI, KCl, KI etc. Halogen is an ancient Greek word meaning 'salt producer'. Halogens have seven electrons in their valence shell and so are monovalent. Halogens Home Back Nextcontent Element Atomic number Electronic configuration Valency State Colour Fluorine 9 2, 7 -1 Gas Greenish but more yellow Chlorine 17 2, 8, 7 -1 Gas Greenish yellow Bromine 35 2, 8, 18, 7 -1 Liquid Dark red liquid Iodine 53 2, 8, 18, 18, 7 -1 Solid Dark purple Astatine 85 2, 8, 18, 32, 18, 7 -1 - - 22. Similarities in the properties of the elements of Group VIIA (17) (Halogens) considering the following points : (1) Electronic configuration (2) Valences . 1) Electronic configuration : In the atoms of the elements of Group VIIA (17), only the outermost shell is incomplete with seven electrons. Exp : 2) Valency : In the elements of Group VIIA (17), have 7 electrons in their valence shell. For complete the octet they required 1 electron. This makes the valency of a halogen one. Therefore they are monovalent. Exp. HF, HBr, HCl. Home Back Nextcontent 23. Similarities in the chemical properties of the elements of Group VIIA (17) (Halogens). 1) Similarities in the chemical properties of halogens can be seen from the similarities of the molecular formulae of their compounds. Compounds with Hydrogen : HF, HCl, HBr, HI, etc. Compounds with alkaline earth metals: BeCl2, MgBr2, CaCl2, etc. Home Back Nextcontent 24. Gradation in the properties of the elements of Group VIIA (17) (Halogens), considering the physical state of the elements. As the atomic number increases down the group, the physical state of halogens show gradation from fluorine to iodine. At normal temperature fluorine and chlorine are gaseous, bromine is a liquid while iodine and astatine are solids. Home Back Nextcontent 25. Zero Group (18) Elements Names and electronic configuration. Zero Group Elements Zero Group Elements ZZ Electronic configuration Electronic configuration Helium (He) Neon (Ne) Argon (Ar) Krypton (Kr) Xenon (Xe) Radon (Rn) Helium (He) Neon (Ne) Argon (Ar) Krypton (Kr) Xenon (Xe) Radon (Rn) 2 10 18 36 54 86 2 2, 8 2, 8, 8 2, 8, 18, 8 2, 8, 18, 18, 8 2, 8, 18, 32, 18, 8 2 2, 8 2, 8, 8 2, 8, 18, 8 2, 8, 18, 18, 8 2, 8, 18, 32, 18, 8 In the atoms of elements of Zero Group all shells are completely filled. Why inert gaseous element not form ionic or covalent compounds? 1) All the electron shells of atom of inert gaseous element are completely filled. Hence they have stable electronic configuration. 2) Due to stable electronic configuration they do not lose, gain or share electron with other atoms. Therefore they do not form ionic or covalent compounds Home Back Nextcontent 26. FOUR BLOCKS OF PERIODIC TABLE BASED ON THE ELECTRONIC CONFIGURATION. Based on electronic configuration of elements the four blocks are, s-block, p-block, d-block and f block. 1) The group IA(1) and IIA(2) together with hydrogen form the s-block elements. The elements in IA are called alkali metals and elements in IIA are called the alkaline earth metals. 2) The elements of s-block except hydrogen are all metals. 3) The group of IIIA to VIIA and Zero group together form the p-block elements. They have 3 to 8 electron in their outermost shell. In the Zero group all the shells are completely filled. 4) In the p-block all three types of elements are present. i.e. a few metals, all metalloids and all non-metals. 5) The group IB to VIIB and the group VIII together form the d-block elements. These elements are also called transition elements. The block is placed between s- and p- block. There last two shells are incompletely filled. The elements of d-block are all metals. 6) The two series lanthanides and the actinides place at the bottom of the table together form the f-block elements. These elements are also called inner transition elements. There last three shells are incompletely filled. The elements of f-block are all metals. Home Back Nextcontent 27. Nextcontent Back 28. Give three examples of each of the following. 1) alkali metals 2) alkaline earth metals 3) metals 4) non-metals 5) metalloids. Give three examples of each of the following. 1) alkali metals 2) alkaline earth metals 3) metals 4) non-metals 5) metalloids. 1) akali metals - Li, Na, K etc. 2) alkaline earth metals - Mg, Ca, Sr etc. 3) metals - Cu, Ag, Au etc. 4) non-metals - F, Cl, Br ect. 5) metalloids - B, Si, Ge, As, Sb, Te, Po. Metalloids or Zig-zag line in the modern periodic table 1) Elements which have properties intermediate between metallic elements and non-metallic elements are called metalloid. 2) The bordering elements along the zig-zag line in the modern periodic table are the metalloids. They are place in IIIA to VIIA group in modern periodic table. 3) All metalloids are p-block elements. Exp. : Boran (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), Tellurium (Te), Polonium (Po) and Astatine (At). Nextcontent Back 29. Give scientific reasons : 1) Valency of elements of group IA is one. 1) Combining power of an atom of element is called valency. It is related with the number of valance electron i.e. electron present in outermost shell of an atom. 2) The number of valence electron present in atom is equal to the group number. Hence elements of group IA contain one valence electron. 3) Therefore atoms of elements in Group IA, can lose, gain or share one electron to complete the outermost shell for stable electronic configuration. 4) Therefore valency of elements of group IA is one. 2) All halogens are monovalent with respect to hydrogen. 1) All halogens contain seven electron in the outermost shell of their atoms. 2) So they can form stable octet by accepting or sharing one electron. All halogens show common valency of one. 3) Hence all halogens are monovalent with respect to hydrogen. 3) The family of noble gases is named as zero group. 1) The number of electron present in outermost shell of an atom of an elements is equal to the group number of the elements. 2) In the atoms of inert gas elements (noble gases), all the shells are completely filled. 3) Due to the stable electronic configuration atoms of elements don't lose, accept or share electrons. Hence valences of noble gases elements is zero. 4) Hence family of noble gases is named as zero group. Nextcontent Back 30. 4) Inert gases exit in the form of free atom. Give scientific reasons : 1) All the shells including outermost shell are completely filled in atoms of Inert gases. 2) Due to stable electronic configuration these elements do not lose, accept or share electrons and do not form ionic or covalent bonds under normal conditions. 3) Hence, they are monoatomic gases and exist in smallest independent unit in the form of free atoms. 5) Valency varies gradually along a period. 1) Valency of an elements is fundamental chemical property. i.e. it is directly related to chemical properties of the elements. 2) The variation of valency along a period follows from the electronic configuration of the elements. 3) In a second period, the valency varies gradually from 1 for group IA, alkali metals to 4 for Group IVA elements and then decrease to 1 for halogens VIIA and 0 for 0 group. Thus, valency varies gradually along a period. 6) In the periodic table, iodine is placed in Group VIIA (17). 1) Iodine has seven electrons in the outermost shell. 2) In the modern periodic table, group number indicates the number of electrons in the valence shell of the atom. Hence Iodine is placed in Group VIIA (17) of the periodic table. Nextcontent Back 31. 7) Actinides are placed at the bottom of the Long form of the Periodic Table. Give scientific reasons : 1) Actinides are inner transition elements. 2) In the atoms of these elements, the last three shells are incomplete. 3) All of them contain two electrons in the outermost shell. All of them show similar chemical properties. Hence, all of these elements should be placed in the same group. As it is not possible the actinides are placed at the bottom of the Long form of the periodic table. 8) Molecular formulae of chlorides of sodium and potassium are similar while those of sodium and magnesium are different. 1) Elements belonging to the same group have the same valence electrons and show similarity in the molecular formulae of their compounds. 2) Sodium (Na) and Potassium (K) belonging to the same group IA (1) of the periodic table. They have one valence electron in their outermost shell. In the formation of chlorides of sodium and potassium, sodium and potassium combines with one chlorine atom each to form sodium chloride (NaCl) and potassium chloride (KCl). Therefore, the molecular formulae of chlorides of sodium and potassium are similar. 3) magnesium belongs to group IIA (2) of periodic table. It has two valence electrons in the outermost shell. In the formation of magnesium chloride, magnesium combines with two chlorine atoms to form magnesium chloride (MgCl2). Molecular formulae of chlorides of sodium and magnesium are different. Nextcontent Back 32. 9) Fluorine is the most reactive among the halogens. Give scientific reasons : 1) Fluorine has the electronic configuration (2,7). 2) It requires only one electron to complete the octet. 3) The atomic size of fluorine is the smallest among the all halogens. Hence, the nuclear attraction on the outermost electrons is maximum. Hence, fluorine is the most reactive among the halogens. 10) Sodium is more metallic than Aluminium. 1) Metals give electrons. Sodium has electronic configuration(2,8,1). It has only one electron in the outermost shell. 2) It can easily give the single electron in the outermost shell. Hence, sodium is a strong metal. 3) Aluminium has electronic configuration (2,8,3). It has three electrons in the outermost shell. 4) Donation of three electrons is more difficult than the donation of one electron. Hence, sodium is more metallic than aluminium. Nextcontent Back 33. 11) All the elements belonging to groups IB to VIIB, VIII are known as transition elements. 1) The last two shells of the atoms of the elements belonging to groups IB to VIIB and VIII, are incompletely filled. These elements shows variable valency. Give scientific reasons : 2) These elements are placed between the most reactive metals on the left and non- metals of the right. Hence all the elements belonging to B groups are known as transition elements. A summary of periodic properties and their variation in groups and periods is given below: Nextcontent Back 34. Distinguish between : 1) Inert gases and Normal elements. Inert gases Normal elements 1) The elements of zero group are called inert gases or noble gases. 1) The elements of s-block and p-block except zero group together are called normal element. 2) The outermost shell of an atom of an inert gas is saturated. 2) The outermost shell of an atom of a normal element is incomplete. 3) Under normal conditions, these elements do not take part in chemical reactions. 3) Under normal conditions, these elements take part in chemical reactions. 4) These elements are gaseous at room them premature. 4) These elements are solid, liquid or gaseous at room temperature. Nextcontent Back 35. Distinguish between : 2) Inert gases and transition elements. 1) Inert gases belong in to zero Group. (18) Inert gasesInert gases Transition elementsTransition elements 1) Transition elements belong to Group IB to VIIB and VIII group.(Group 3 to 12) 2) The outermost shell of an atom of an inert gas is saturated, in the case of helium with 2 electron and in the case of other gases with 8 electron. 2) The last two shells of an atom of a transition element are incomplete. 3) Under normal conditions, these elements do not take part in chemical reactions. 3) Under normal conditions, these elements take part in chemical reactions. 4) These elements are gaseous at room temperature. 4) These elements are solid metals at room temperature. Nextcontent Back 36. Back Distinguish between : 3) Transition elements and inner transition elements. Transition elementsTransition elements Inner transition elementsInner transition elements 1) The last two shell of the atoms of transition elements are incompletely filled. 1) The last three shells of an atom of inner transition element are incompletely filled. 2) They belong to groups IB to VIIB, and VIII (group 3 to 12) and they are placed between s- and p- block. 2) They are placed in two separate series (rows) at the bottom of the periodic table. 3) They belong to d- block of the periodic table. 3) They belong to f-block of the periodic table. Nextcontent 37. Distinguish between : 4) s-block elements and p-block elements. s-block elementss-block elements p-block elementsp-block elements 1) The groups IA (1) and IIA (2) together with hydrogen constitute the s- block. 1) The group IIIA (13) to VIIA (17) and the Zero group (18) constitute the p- block. 2) They have one or two electrons in the outermost shell. 2) They have three to eight electrons in the outermost shell. 3) The elements of s-block (except hydrogen) are all metals. 3) The elements of p-block include a few metals, all non-metals and all metalloids. Back Nextcontent 38. CONTENT 1) Moseleys contribution to the classification of elements. 2 2) Modern Periodic Table 3 3) Isotopes of Na 4 4) Sketch of the Modern Periodic Table. 5 5) Normal elements 6 6) Transition Elements 7 7) Inner transition elements 8 8) Inert gases 9 9) Main Features of the Long form of the Periodic Table. 10 10) Elements in first period 11 11) Elements in Second period 12 12) Elements in Third period 13 13) The periods in the modern periodic table. 14 14) The trends in the valences of the elements in a period. 15 Next Page Back Next Back Page 39. 15) Groups of the modern periodic table with reference to the properties of the Elements. 16 CONTEST 16) Elements and their Electronic Configuration of the Group IA and their valency. 17 17) The similarities in the chemical properties of the compounds of alkali metals. 18 18) Elements of group IIA and their atomic numbers and electronic configuration. 19 19) The similarities in the chemical properties of the compounds of Alkaline earth metals. 20 20) Halogens 21 21) Similarities in the properties of the elements of Group VIIA (Halogens) considering electronic configuration and valances. 22 22) Similarities in the chemical properties of the elements of Group VIIA (17) (Halogens). 23 Next Page Back Next Back Page 40. 23) Gradation in the properties of the elements of Group VIIA (17) (Halogens), considering the physical state of the elements. 24 CONTEST 24) Zero Group (18) Elements-Names and electronic configuration. 25 25) FOUR BLOCKS OF PERIODIC TABLE BASED ON THE ELECTRONIC CONFIGURATION. 26 26) PERIODIC TABLE SHOWING 4-BLOCKS OF ELEMENTS 27 27) Metalloids or Zig-zag line in the modern periodic table 28 28) Scientific reasons : 1 to 3 29 29) Scientific reasons : 4 to 6 30 30) Scientific reasons : 7 and 8 31 31) Scientific reasons : 9 and 10 32 32) Scientific reasons : 11 and summary of properties of elements 33 33) Distinguish between : 1) Inert gases and Normal elements. 34 34) Distinguish between : 2) Inert gases and transition elements. 35 35) Distinguish between : 3) Transition elements and inner transition elements. 36 36) Distinguish between : 4) s-block elements and p-block elements. 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