Chapter 8 Periodic Relationships Among the Elements 8.2 Periodic Classification of the Elements 8.3 Periodic Variation in Physical Properties Effective nuclear charge Atomic Radius Ionic Radius 8.4 Ionization Energy 8.5 Electron Affinity Electronegativity (ch.9 p. 377-378) p357: 8.5, 8.8, 8.12, 8.20, 8.24, 8.26, 8.28, 8.30, 8.32 p358: 8.36, 8.38, 8.40, 8.44, 8.46 p358: 8.52, 8.54, 8.62, 8.64 Dr.Laila Al-Harbi

Metals – metalloids – non metals in periodic table Chapter 8 :Classification of elements Metals – metalloids – non metals in periodic table 1-Representative elements (main group elements): Groups 1A to 7A Incompletely filled s and p orbitals 1A = alkaline metals 2A = alkaline earth metals 7A = halogens 2-Noble gas group: Group 8A Filled p subshell (except He which has a filled s orbital) 3-Transition metal Groups 1 B to 8 B Unfilled d orbitals 4-Lanthanides and actinides Incompletely filled f subshells Lanthanides = rare earth metals

ns ns np ns ns (n-1)d Chapter 8 :Block system of periodic table S block p block ns ns (n-1)d d block f block

The elements in group 4A :carbon (C) is a nonmetal, silicon (Si)and germanium (Ge)are metalloids, and tin(Sn) and lead(Pb) are metals . halogens(nonmetals)(Florine(F),Iodine(I),Chlorine(Cl),Bromine(Br)) form an ion with a charge of (-1)(F-,I-,Cl-,Br-) Dr.Laila Al-Harbi

ns2np6 ns1 ns2np1 ns2np2 ns2np3 ns2np4 ns2np5 ns2 d10 d1 d5 4f 5f Ground State Electron Configurations of the Elements ns1 ns2np1 ns2np2 ns2np3 ns2np4 ns2np5 ns2 Within a Period number of electrons increase Within a group (n) increase d10 d1 d5 4f 5f Dr.Laila Al-Harbi

Valence electrons the outermost electrons Chapter 8 : Classification of the Elements Valence electrons the outermost electrons Core electrons are nonvalence electrons in an atom Example Na 10 core electrons 1 outermost (valence electron) Cl 10 core electrons 7 outermost (valence electron)

ELECTRON CONFIGURATIONS - THE GROUND STATE 1H 1s1 2He 1s2 3Li 1s22s1 4Be 1s22s2 5B 1s22s22p1 6C 1s22s22p2 7N 1s22s22p3 8O 1s22s22p4 9F 1s22s22p5 10Ne 1s22s22p6 period 1 11Na 1s22s22p63s1 12Mg 1s22s22p63s2 13Al 1s22s22p63s23p1 14Si 1s22s22p63s23p2 15P 1s22s22p63s23p3 16S 1s22s22p63s23p4 17Cl 1s22s22p63s23p5 18Ar 1s22s22p63s23p6 period 2 Period 2 Period 3 Dr.Laila Al-Harbi

19K 1s22s22p63s23p64s1 20Ca 1s22s22p63s23p64s2 21Sc 1s22s22p63s23p64s23d1 22Ti 1s22s22p63s23p64s23d2 23V 1s22s22p63s23p64s23d3 NOT 4s23d4 24Cr 1s22s22p63s23p64s13d5 There is a tendency toward half-filled and completely filled d subshells. This is a consequence of the closeness of the 3d and the 4s orbital energies. Dr.Laila Al-Harbi

Additional exceptions are Mo 5s14d5; Ag 5s14d10; Au 6s15d10 The 3d level becomes more stable as we move from left to right on the periodic chart. Remember there is an increase in the number of protons consequently, an increase in the number of electrons as we move from left to right on the chart. 30Zn 1s22s22p63s23p64s23d10 31Ga 1s22s22p63s23p64s23d104p1 32Ge 1s2 2s22p63s23p64s23d104p2 33As 1s2 2s22p63s23p64s23d104p3 34Se 1s22s22p63s23p64s23d104p4 35Br 1s22s22p63s23p64s23d104p5 36Kr 1s22s22p63s23p64s23d104p6 25Mn 1s22s22p63s23p64s23d5 26Fe 1s22s22p63s23p64s23d6 27Co 1s22s22p63s23p64s23d7 28Ni 1s22s22p63s23p64s23d8 NOT 4s23d9 29Cu 1s22s22p63s23p64s13d10 Additional exceptions are Mo 5s14d5; Ag 5s14d10; Au 6s15d10 That is reasonable considering their position on the periodic chart. Dr.Laila Al-Harbi

The general formula of an element un group IA is S2p1 s1p1 The general formula of an element un group 8A is S2 S1 S2p6 s1p1 Dr.Laila Al-Harbi

Electron Configurations of Cations and Anions Of Representative Elements Na [Ne]3s1 Na+ [Ne] Atoms lose electrons so that cation has a noble-gas outer electron configuration. Ca [Ar]4s2 Ca2+ [Ar] Al [Ne]3s23p1 Al3+ [Ne] H 1s1 H- 1s2 or [He] Atoms gain electrons so that anion has a noble-gas outer electron configuration. F 1s22s22p5 F- 1s22s22p6 or [Ne] O 1s22s22p4 O2- 1s22s22p6 or [Ne] N 1s22s22p3 N3- 1s22s22p6 or [Ne] Dr.Laila Al-Harbi

Cations and Anions Of Representative Elements +1 +2 +3 -3 -2 -1 Dr.Laila Al-Harbi

10Na+, 10Al3+, 10F-, 10O2-, and 10N3- 11Na , 13Al , 9F , 8O , and 7N Na+: [Ne] Al3+: [Ne] F-: 1s22s22p6 or [Ne] O2-: 1s22s22p6 or [Ne] N3-: 1s22s22p6 or [Ne] Na+, Al3+, F-, O2-, and N3- are all isoelectronic with Ne What neutral atom is isoelectronic with H- ? H-: 1s2 same electron configuration as He isoelectronic – same number of electrons 10Na+, 10Al3+, 10F-, 10O2-, and 10N3- 11Na , 13Al , 9F , 8O , and 7N Dr.Laila Al-Harbi

Electron Configurations of Cations of Transition Metals When a cation is formed from an atom of a transition metal, electrons are always removed first from the ns orbital and then from the (n – 1)d orbitals. Mn: [Ar]4s23d5 Fe: [Ar]4s23d6 Fe2+: [Ar]4s03d6 or [Ar]3d6 Mn2+: [Ar]4s03d5 or [Ar]3d5 Fe3+: [Ar]4s03d5 or [Ar]3d5 keep in mid that most transition metals an form more than one cation and frequently the cations are not isoeletronic with the preceding noble gases Dr.Laila Al-Harbi

What is the ground-state electron configuration of Mn? 4s1 3d5 4s2 3d6 4s2 3d5 What is the ground-state electron configuration of Mn+2 What is the ground-state electron configuration of Fe+2 3d6 4s1 3d5 4s2 3d6 4s2 3d5 What is the ground-state electron configuration of Fe+3 3d5 التوزيع الالكتروني للمدار الاخير لعناصر المجموعة الانتقالية هو ns2(n-1)d كما هو واضح في المثال الاول ..... و في حال فقدها للالكترونات فانها تفقد الالكترونات أولا من المدار s ( كما في المثال الثاني و الثالث) و اذا كانوا أكثر من 2 فانها تفقد من الباقي من d كما هو واضح في المثال الاخير .... و يمكنك القيام بهذا لجميع الذرات Dr.Laila Al-Harbi

Gallium element is found in the periodic table in (a) period 3, group 1B (b) period 3A, group 4 (c) period 4, group 1A (d) period 4, group 3A Answer (d) Dr.Laila Al-Harbi

Titanium (Ti) element is found in the periodic table in (a) s-block (b) P-block (c) d-block (d) f-block The 15th element in the period 4 is Dr.Laila Al-Harbi

Which of the following species is isoelectronic with Cl- (a) F- (b) O2- (c) K+ (d) Na+ Answer: (c) Dr.Laila Al-Harbi

Which of the following are have the same number of electrons (isoelectronic)? 5. 1. 2. 3. 4. None of the above

Example 8.1 p328 An atom of a certain element has 15 electrons. Without consulting a periodic table, answer the following questions: (a) What is the ground-state electron configuration of this element? 1s2 2s2 2p6 3s2 3p3 (b) How should be element be classified? Period 3, group 5A The element is representative element. (c) Is the element diamagnetic or paramagnetic paramagnetic Valence electrons 3s2 3p3

Periodic Variation in Physical Properties Effective nuclear charge شحنه النواه الفعالة Atomic Radius نصف القطر الذري Ionic Radius نصف القطر الايوني Ionization Energy طاقة التأين Electron Affinity الألفة الالكترونية Electronegativity السالبية الكهربية

8.3 Periodic Variation in Physical Properties Effective nuclear charge Atomic Radius Ionic Radius lower effective charge on nucleus • inner electrons shield outer electrons from nucleus • shielding effect of electrons reduces the attraction between the nucleus and the electrons • repulsive forces between electrons offset the attractive forces الشحنة النووية الفعالة: هي الشحنة الموجبة التي تشعر بها الالكترونات الموجودة في تلك الذرة وخاصة في المستوى الأخير للذرة. Dr.Laila Al-Harbi

Effective nuclear charge (Zeff) is the “positive charge” felt by an electron. Zeff = Z - s 0 < s < Z (s = shielding constant) Zeff  Z – number of inner or core electrons Zeff Core Z Radius Na Mg Al Si 11 12 13 14 10 1 2 3 4 186 160 143 132 Within a Period as Zeff increases radius decreases decreases Dr.Laila Al-Harbi

Increasing Zeff increasing Z (nuclear charge) Increasing n increases the shielding effect Decreasing Zeff

The atomic radius The atomic radius is ½ the distance between the 2 nuclei of the adjacent atoms. Atomic radius - a number of physical properties of elements are related to the size of an atom Atomic radius, in general, decreases as we move from left to right in a row of the periodic table (a Period ). Atomic radius increases from top to bottom in a family or group. The ionic radius is the radius of anions and Cations Dr.Laila Al-Harbi

Dr.Laila Al-Harbi

Decreasing atomic radius increasing Z increases the effective nuclear charge so the added valence electron is more strongly attracted by the nucleus so atom size shrinks n increases so atomic radius increases Increasing atomic radius

Within a group atomic radius increase Within a Period atomic radius decreases Within a group atomic radius increase Dr.Laila Al-Harbi

Example 8.2 p332 Referring to a periodic table, arrange the following atoms in order of increasing atomic radius: P , Si , N increasing … small to large ( small) N < P < Si (large) arrange the following atoms in order of decreasing radius: C , Li, Be decreasing … large to small (large) Li > Be > C (small) Dr.Laila Al-Harbi

ionic radius is the radius of anions and cations Anions>>gain electrons >>> ionic radius increase because the nuclear charge remain the same but the repulsion resulting from the additional electrons enlarges the domain of the electron Cations… lose electron …ionic radius decrease because removing one or more electron from an atom reduces electron-electron repulsion but the nuclear charge remains the same so the electron clouds shrinks , and the cation is smaller than atom Cation is always smaller than atom from which it is formed. Anion is always larger than atom from which it is formed. Dr.Laila Al-Harbi

Atom Anion ionic radius increase Cation Atom ionic radius decrease Dr.Laila Al-Harbi

Cations is smaller than anions ( 10Na+< 10F-) Isoelectronic ions Cations is smaller than anions ( 10Na+< 10F-) The greater effective nuclear charge of 10Na+results in smaller radius. Isoelectronic cations 10Al+3< 10Mg+2 < 10Na+ Isoelectronic anions 10F- < 10O-2 < 10N-3 Dr.Laila Al-Harbi

ionic radius increase Dr.Laila Al-Harbi

Example 8.3 For each of the following pair ,indicate which is larger A) 10F- ,10N-3 10N-3 B) 10Mg+2 , 18Ca+2 18Ca+2 C) Fe+2 , Fe+3 Fe+2 For each of the following pair ,indicate which is smaller A) 18K+ ,2Li+ 2 Li+ B) 10N-3 , 18P-3 10N-3 C) Au+ , Au+3 Au+3 Dr.Laila Al-Harbi

Order the following according to increasing atomic/ionic radius. N3– Li+ C O2– C < Li+ < O2– < N3– N3– < O2– < C < Li+ Li+ < C < N3– < O2– Li+ < C < O2– < N3– ايونات من مجموعات مختلفه؟ الكاتيونات اصغر من الانيونات كاتيونات: الاصغر ذو الشحنه الموجبه الاكبر انيونات : الاصغر ذو الشحنه السالبه الاصغر

Ionization energy I1 < I2 < I3 Ionization energy (IE) is the minimum energy (kJ/mol) required to remove an electron from a gaseous atom in its ground state. The higher ionization energy, the more difficult it is to remove the electrons. The first ionization energy is the amount of energy required to remove the 1st electron from an atom in the gaseous state. I1 + X (g) X+(g) + e- I2 + X (g) X2+(g) + e- I3 + X (g) X3+(g) + e- I1 first ionization energy I2 second ionization energy I3 third ionization energy I1 < I2 < I3 Dr.Laila Al-Harbi

The higher ionization energy, the more difficult is to remove the electrons.

Variation of the First Ionization Energy with Atomic Number A larger effective nuclear charge more tightly held outer electron, higher first ionization energy. He has the highest first ionization energy of all the elements. Filled n=1 shell Filled n=2 shell Filled n=3 shell Filled n=4 shell Filled n=5 shell

Increasing First IE (I1) increasing Z increases the effective nuclear charge so the added valence electron is more strongly attracted by the nucleus and harder to remove electrons n increases so the Zeff decreases and easier Decreasing First IE I1 to remove electrons

The first IE increase from left to right in period. When electron is removed from atom, repulsion among the remaining electrons decrease, because nuclear charge remains constant. More energy is needed to remove another electron from the positively charged ion. The IE for nonmetal is higher than metal , IE for metalloid fall between metals and nonmetals. The first IE increase from left to right in period. But there is some exceptions Group 2A (ns2 ) higher than 3A (ns2 np1) in the same period Example (Be & B) B) Group 5A (ns2 np3) higher than 6A (ns2 np4) in the same period Example (N & O)

Some irregularities (Exceptions) of Ionization Energy 1A < 3A < 2A < 4A < 6A < 5A < 7A < 8A √ Increasing First Ionization Energy Decreasing First Ionization Energy

Example 8.4 (a) p340: Which atom should have a smaller first ionization energy: oxygen or sulphur? Solution: O & S are in group 6A O: [He] 2s2 2p4 S: [Ne] 3s2 3p4 The valence electrons in sulphur are farther ابعد from the nucleus → removing of them is easier Thus: I1 (S) < I1 (O) Increasing First Ionization Energy Decreasing First Ionization Energy

Example 8.4 Which atom should have a higher second ionization energy (Li or Be) Li (2s1) < Be (2s2 ) … first ionization energy Li+ (1s2) > Be+ (2s1 ) … second ionization energy Because 1s electrons shield 2s electrons much more effectively than they shield each other , we predict that it should be easier to remove a 2s electron from Be+ than to remove a 1s electron from Li+ Increasing First Ionization Energy Decreasing First Ionization Energy Add periodic table here, if possible.

Electron affinity هي كمية الطاقة الممتصة عند إضافة إلكترون لذرة غازية متعادلة لتكوين أيون غازي بشحنة مقدارها -1. وتصبح شحنتها سالبة عند انطلاق الطاقة. Electron affinity is the negative of the energy change that occurs when an electron is accepted by an atom in the gaseous state to form an anion. X (g) + e- X-(g) F (g) + e- X-(g) O (g) + e- O-(g) DH = -328 kJ/mol EA = +328 kJ/mol DH = -141 kJ/mol EA = +141 kJ/mol The higher electron affinity, the greater affinity to accept the electron Dr.Laila Al-Harbi

Increasing Electron affinity increasing Z increases the effective nuclear charge so the more electron acceptance and greater electron affinity n increases so the Zeff decreases and less electron acceptance Decreasing Electron affinity

Highest Electron affinity is for halogen Lowest Electron affinity is for group IA Dr.Laila Al-Harbi

The EA increase from left to right in period. The EA for nonmetal is higher than metal , EA for metalloid fall between metals and nonmetals. The EA increase from left to right in period. But there is some exceptions A) Group 2A (ns2 ) lower than 1A (ns1 ) in the same period B) Group 5A (ns2 np3) lower than 4A (ns2 np2) in the same period Noble gases have the lowest electron affinities The electron affinity of (F) is lower than that for the (Cl) 8A < 2A < 1A < 3A < 5A < 4A < 6A < 7A

Chapter 8 : Electron Affinity > >

Q: Which choice correctly lists the elements in order of decreasing electron affinity? من الأكبر إلى الأصغر O, Cl, B, C O, Cl, C, B Cl, O, C, B Cl, O, B, C Increasing Electron affinity Decreasing Electron affinity Exceptions?? No Apply the rule of the period until you find a group apply the rule of the group Cl > O > C >B