Periodic Shobhit Nirwan.pdf

SHOBHIT NIRWAN's DESIGNED CLASSIFICATION OF ELEMENTS & PERIODICITY IN PROPERTIES NEW NOTES FOR CLASS 11 2022 EXAMS  OVERVIEW OF THE CHAPTER 1. Basic Fundamentals 2. Dobernier Law 3. De – Chancourtis 4. Newlands Law of Octaves 5. Lother Meyer Atomi...

SHOBHIT NIRWAN's DESIGNED CLASSIFICATION OF ELEMENTS & PERIODICITY IN PROPERTIES NEW NOTES FOR CLASS 11 2022 EXAMS  OVERVIEW OF THE CHAPTER 1. Basic Fundamentals 2. Dobernier Law 3. De – Chancourtis 4. Newlands Law of Octaves 5. Lother Meyer Atomic Volume Curves 6. Mendeleev Classification of Elements 7. Moseley Equations 8. Modern Periodic Law 9. Long form of Periodic Table 10. IUPAC Nomenclature for Elements 11. Classification of Elements on the basis of their electronic configuration. (i) s – block Elements (ii) p – block Elements (iii) d – block Elements (iv) f – block Elements 12. Classification on based on chemical properties (i) Inert Gas (ii) Representative Elements (iii) Transition Elements (iv) Inner Transition Elements 13. Classification: Metals, Non – metals & Metalloids 14. Trends in Physical Properties (a) Atomic Radius (b) Ionic Radius (c) Ionization Energy/ Ionization Potential (d) Electron gain Enthalpy/ Electron Affinity (e) Electronegativity 15. Valency, Covalency & Oxidation State 16. Diagonal Relationship 17. Anomalous Properties of Second Period Elements 1.Basic Fundamentals: At present there are 118 elements Recently discovers elements are not natural but synthetic. Elements coming after 92 are known as “Trans Uranic Elements” or synthetic elements and they are radioactive. 2.Dobereiner Law of Triads:- A triad is certain group of 8 elements with similar properties. According to him, the atomic weight of the middle element was approximately the arithmetic mean of the other 2. Also the properties of middle element were in b/w those of the other two. Dobereiner’s relationship, referred to as the “Law Of triads”. Ex: (i) Li, Na, K (ii) S, Se, Te (iii) Cl, Br, I (iv) Ca, Sr, Ba 3.De-Chancourtois Classification: De-Chancourtois arranged the elements in order of increasing atomic weights. Made cylindrical table of elements displaying recurrence of properties. 4.Newland’s Law of Octaves: Arranged elements in increasing order of atomic weight. Every 8th element had similar properties with 1st element. The relationship was just like every eighth note that resembles the first in octaves of music. Drawbacks: It seemed to be true only for elements up to Calcium. 5.Lother Meyer Atomic Volume Curves: Plotted a graph b/w atomic volume against atomic weight. Atomic weight = at.Volume × density Finding of Lother Meyer Curves:- 1. alkali metals ( Na, K , Rb , Cs , Fr ) are at peaks of curves. 2. alkaline earth metals (Be, Mg, Ca, Sr, Ba) are at descending part of curve. 3. Halogens are ascending part of curve (F,Cl, Br,I) 4. Transition elements are in the broad minimas of the curve. अब होगी असली हीरो की एं ट. ी नाम Mendeleev, पूरा नाम Mr. Dimitri Mendeleev Dobernier ने start की थी कहानी और पूरी Mendeleev ने की l चलो Mendeleev classification समजते चलो समाजते 6.Mendeleev Classification of Elements:- Statement:- “The properties of elements are a periodic function of their atomic weights” 1. Also known as short form of periodic table. 2. he relied on the similarities in the empirical formulas and properties of the compounds formed by the elements. 3. He not only followed the order of atomic weights but also placed elements with similar properties. (a) Almost same atomic weights Ex: Fe(56), Co(59), Ni(59) (b) Atomic weights increasing constantly Ex: K(39), Rb(85), Cs(133) 4. Vertical columns – groups (9 groups) Horizontal rows – periods (7 periods) 4. First 3 periods are short periods & remaining are long periods. 5. Each long period has 2 rows of elements or 2 series of elements. 6. Leaving O and VIII, each group is subdivided into subgroups known as A & B groups. 7. Group VIII of Mendeleev’s table consists of 3 triads known as transition triads. (i) Iron, Cobalt, Nickel (ii) Ruthenium, Rhodium, Palladium (iii) Osmium, Iridium, Platinum 8. Zero group elements were not known at the time of Mendeleev & later introduced by Ramsay. 9. Mendeleev left some gaps for some undiscovered elements (i) Eka boron presently known as scandium (ii) Eka silicon – Germanium (iii) Eka aluminium – gallium 10. He corrected the weights of Beryllium, Iridium and Osmium Merits:- 1. Gave an elaborate system of classification based on physical and chemical properties. 2. Broadly left some gaps for undiscovered elements like Ge , Sc. Demertis:- 1. Some elements with higher atomic weight were placed before lower atomic weight elements. Ex: (i) Ar - K (ii) Co – Ni (iii) Te – I (iv) Th – Pa 2. Position of hydrogen is not specified. 3. No place for noble gas. 4. Isotope are not included. 5. Cause of periodicity is not known. 7.Moseley Equation:- The frequency ν of characteristic X-rays is related to atomic number Z by Moseley's law, √ν=a(Z−b), where a , b are constants. Atomic number increases, frequency of x-rays increases. 8.Modern Periodic Law: Physical & chemical properties of elements are periodic functions of their atomic number. Note : Atomic no. is the number of protons or the number of electrons in a neutral atom. 9.Long Form of Periodic Table: Bohr constructed the long form of periodic table. Based on electronic configurations of elements. There are 18 groups ( vertical columns) and 7 periods ( horizontal rows). Periods: In periods, elements are arranged in increasing order of ‘z’. The electron by which an element differ from its previous element is called “differentiating electron”. In each period, the differentiating electron enters in ‘s’ orbital in 1st element and ‘p’ orbital in last element. Followed by Afbau- Rule (n+l) order values. Period no. corresponds to the highest principal quantum number (n) of elements in the period. Ex: 1st period contains 2 elements, the subsequent periods contains of 8 ,8, 18 ,18 ,32 elements. The 7th period is incomplete and like the 6th period would have a theoretical maximum of 32 elements.  In this form, 14 elements of both sixth and seventh period (lanthanoids and actinoids) are placed in separate panels at bottom. Groups: Contains 18 vertical columns which are divided into main groups & subgroup at I A & to VII A, 0 groups and VIII B, IV B, VB, VI B, VIIB, VIII B, IB and II B groups. 10.IUPAC Nomenclature for Elements(z>100) The roots are put together in order 9 digits which make up the atomic no. and ‘ium’ is added at the end. Digit Latin Word 0 Nil n 1 Un u 2 bi b 3 Tri t 4 Quad q 5 Pent p 6 Hex h 7 Sept s 8 Oct o 9 enn e  Q1)What would be the IUPAC name and symbol for the element with atomic number 120? Ans: The roots for 1, 2 and 0 are un, bi and nil, respectively. Hence, the symbol and the name respectively are Ubn and unbinilium. Q2)How would you justify the presence of 18 elements in the 5th period of the Periodic Table? Solution When n = 5, l = 0, 1, 2, 3. The order in which the energy of the available orbitals 4d, 5s and 5p increases is 5s < 4d < 5p. The total number of orbitals available are 9. The maximum number of electrons that can be accommodated is 18; and therefore 18 elements are there in the 5th period. 11.Classification of Elements on the Basis of their Electronic Configuration: The Aufbau principle and the electronic configuration of atoms provide theoretical foundation for the periodic classification. This similarity arises because these elements have the same number of electrons in their outermost shells. Elements are classified into four blocks based on the orbital into which the differentiating e- enters. a) s- block elements b) p – block elements c) d - block elements d) f – block elements (i) S – block Elements: Differentiating electron enters into s – orbtial. Contains two groups: I A – alkali metals (ns1) IIA – alkaline Earth metals (ns2) Highly reactive metals with low ionization enthalpy. Readily lose outermost electron and form +1 ion or +2 ion. Metallic character & reactivity increases down the group. Never found in free state due to high reactivity. Compounds of s-block elements are ionic except, (lithium & Berullium) (ii) P- Block Elements: Differentiating electron enters into p-orbital General outer shell configuration ns2np1-6 Together with s block elements called as representative elements. Arranged in 6- groups they are form III A to VII A and 0 – groups (or) 13-18 groups. Some group have special names: 16 – chalcogens 17 – halogens 18 – noble gas Noble gas elements are least reactive and inert. Outer most orbital is completely filled in noble gases. Halogens and chalcogens have high negative electron gain enthalpy and readily add one or 2 electron to attain stable electronic configuration. Q3) Helium belongs to S block group elements but still it is placed in p block. Why? Ans : It is because it has completely filled valence shell ( 1 s2) ans therefore exhibits (iii) nobleElements: d – Block gas properties. Differentiating electron enters into inner d orbitals (n-1)d subshell. Also called as transition metals. General electronic configuration (n-1)d1-10 ns1-2. d – block elements are placed between s – block and p – block elements They all are metals.  Show variable valencies , from coloured ions, para magnetism, and also used as catalysts. Zn, Cd, Hg are not transitions elements. They do not show properties of transition elements and have (n-1)d10 ns2. (iv) f – Block Elements: Also called as inner transition elements. Differentiating electron enters into f – subshell of anti – penultimate i.e (n-2) shell General electronic configuration (n-2)f1-14 (n-1)d0 (or) 1 ns2 Placed at the bottom of periodic table in two rows. 4f series → lanthanoids 5f series → actinoids Actinoids elements are radioactive. They all are metals. They have properties similar to d – block elements. The elements after uranium are called as Transuranium elements. Q4) The elements Z = 117 and 120 have not yet been discovered. In which family /group would you place these elements and also give the electronic configuration in each case. Solution: the element with Z = 117, would belong to the halogen family (Group 17) and the electronic configuration would be [Rn] 5f 146d107s 27p5.The element with Z = 120, will be placed in Group 2 (alkaline earth metals), and will have the electronic configuration [Uuo]8s2. 12.Classification Based on Chemical Properties: Type 1: Inert Gases 1. He, Ne, Ar, Kr, Xe, Rn are called as inert gases (18th group) 2. Except He(1s2) all other elements have ns2 np6 configuration. 3. Due to the stable inert gas configuration they are chemically inert and have high ionization enthalpy. 4. All are monoatomic gases. 5. They all are also called as rare and noble gases. Type 2: Representative Elements 1. Outermost shell is incompletely filled. 2. Excluding 18th group, remaining ‘S’ & ‘P’ block elements (IA, IIA, IIIA, IVA, VA, VI A, VII A) are called as representative elements. 3. Most of these elements are abundant and active. 4. Outer electronic configuration ns-1 np1-5 5. Metals, Non-metals and metalloids are present. Type 3: Transition Element 1. In these elements the ultimate and penultimate shells are incompletely filled. 2. Elements which have incomplete or partially filled ‘d’ orbital are called as transition elements. 3. General electronic configuration is (n-1)d1-9 ns0-2 4. They exhibits some special properties like variable oxidation states, form coloured ions, from alloys and etc. Type 4: Inner Transition Elements: 1. In these elements, 3 outermost shells are incompletely filled n, (n-1) & (n-2) 2. The f-block elements are called as inner transition elements. 3. General configuration : (n-2)f1-14 (n-1)0 (or)1 ns2 4. They are placed separately at the bottom of periodic table 5. Most of them are radioactive elements 4f series → lanthanoids 5f series → actinoids 13.Classification: Metals, Non-metals and Metalloids Metals Metalloids Non – Metals Comprise 78% of known Some elements like Located at top right elements silicon, germanium, hand side of periodic arsenic, antimony, table. tellurium. Present at left side of Bordering this line and Usually solids or gases at periodic table(usually) running diagonally room temperature. across periodic table Usually solid at room Show properties of both With low melting and temperature (except metals and non- metals boiling points. (except mercury) called as metalloids carbon and boron)  High melting and boiling Poor conductor of heat point and electricity. Good conductor of heat Brittle neither ductile & electricity not malleable. Malleable Non – metallic character (can be flattened into increases as we from left thin sheets ) to right. Ductile (can be drawn into wires) KK3B: 3B: Pseudo PseudoInert InertGas GasElectronic ElectronicConfiguration: Configuration: Presence Presenceofof18e 18ein - - inoutermost outermostshell shellisiscalled calledpseudo pseudoinert inertgas gasconfiguration configuration Ex: Palladium. Ex: Palladium. Elements के बारे म' तो एक idea आगया… हम लोग का next step उनके properties जानने का है. दे र 8कस बात क: चलो सीखे l 14.Trends In Physical Properties: There are numerous physical properties of elements such as Melting point and Boiling point, heat of fusion and vapourisation etc. a) Atomic Radius: The distance between the centre of the nucleus & the electron cloud of most energy level is called as atomic radius. It refers to both covalent or metallic radius depending on the element. It depends on: 1. Nature of bonding 2. Number of bonds 3. Oxidation Number 4. Coordination number 5. Bond character  Measured in angstrom, nanometer, picometer units. 1 Å = 10-1nm 1 Å = 102pm 1 Å = 10-10m 1 Å = 10-7mm Atomic radius across period decreases. Atomic radius increases with increase in atomic number down the group due to the addition of shells as number of outer electrons increases. Atomic radius of noble gases should not be considered here, being monoatomic their radius are very large. Q5) Why atomic radius decreases across period?? Answer:- it is due to the increase in nuclear charge increases with increase in atomic number and the outer electrons, within the period are in the same valence shell. Resulting in the increased attractions of electrons to the neutrons.  b) Ionic Radius: It is the distance between the nucleus and the electron in the outer most shell of its ion. Removal of electrons from atom → cation Gain of electrons from atom → anion In cation → size is smaller than parent atom because it has fewer electrons, while nuclear charge remains constant. In anion → size is larger than parent atom, due to addition of electrons, results in increase in repulsion among electrons and decrease in nuclear charge. K3B: Isoelectric Species : Species having same number of e-. In isoelectric species, the size increases with increase of negative charge & decreases with increase in positive charge. Ex: C- > N-3 > O-2 > F- > Ne > Na+ > Mg+2 > Al+2 > Si+4 Q6)Considering the atomic number and position in the periodic table, arrange the following elements in the increasing order of metallic character : Si, Be, Mg, Na, P. Ans: Metallic character increases down a group and decreases along a period as we move from left to right. Hence the order of increasing metallic character is: P < Si < Be < Mg < Na. Q7)Identify isoelectronic species a) Mg+2 & Al+3 c) N-3 & C-5 b) Al+2 & Mg+2+ d) N-3 & C-4 Answer:- (a) & (d) are isoelectronic species. Reason (a) Mg+2 → atomic number of Mg = 12 No. of electron = 12 – 2 = 10 e- Al+3 → atomic number of Al = 13 No. of electron = 13 – 3 = 10 e- (d) N-3 → atomic number of N = 7 No. of electron = 7 – (-3) = 10 e- C-4 → atomic number of C = 6 No. of electron = 6 – (-4) = 10 e- Q8)What is lanthanoide contraction?? Answer:- The decrease in the size of atoms or ions (M+3) with increase in the atomic number among lanthanoides due to dispersed shape and poor screening effect of f – orbital electron clouds is called as lanthanoid contraction. Consequences:- 1. Properties of elements are close and similar. 2. Zr ≈ HF ( atomic size) Mo ≈ w Nb ≈ Ta Q9) Which of the following species will have the largest and the smallest size? Mg, Mg2+, Al, Al3+. Solution: Atomic radii decrease across a period. Cations are smaller than their parent atoms. Among isoelectronic species, the one with the larger positive nuclear charge will have a smaller radius. Hence the largest species is Mg; the smallest one is Al3+. Basic strength of hydroxides : as the size of the lanthanide ion decreases from Ce+3 to Lu+3 , the covalent character of M-OH bond increases and hence the basic strength decreases. Thus, Ce(OH)3 is the most basic while Lu(OH)3 is least basic. c)Ionization Enthalphy / Ionization Energy: The minimum amount of energy required to remove the loosely bonded electron from the outermost shell form an isolated neutral gases is called as ionization potential. +1 M(g) + I.E1 → M(g) + 1e- It is an endothermic process , energy is always required to remove electrons from an atom hence ionization enthalpies are always positive. Expressed in KJ/mol. Energy required to remove an e- form unipositive gaseous ion to convert into dipositive gaseous is called second ionization potential. +2 M+(g) + I.E2 → M(g) + 1e- I.E depends on 1. atomic size 2. nuclear charge 3. screening effect 4. electronic configuration  IE1