1. Periodic Relationships Among the Elements
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2. Chapter 8 8.2-Periodic classification of the elements (326-330) .
8.3-Periodic variation in physical properties ( ).
8.4-Ionization energy- Electron affinity .
( ) .
9.5-Electronegativity ( ).

3. When the Elements Were Discovered
8.1

4. Ground-State Electron Configurations of the Elements (IUPAC)
ns2np6
ns1
Within a Period number of electrons increase
ns2np1
ns2np3
ns2np4
ns2np2
ns2np5
Within a group (n) increase
ns2
d10 d1 d5 4f 5f
8.2

5. Classification of the Elements
Categories of elements correspond to which subshell is last filled
1-Representative elements (main group elements):
Groups 1A to 7A
Incompletely filled s and p orbital's
2-Noble gses:
Group 8A
Filled p subshell or orbital's (except He which has a filled s orbital)
3-Transition metal (d-block elements)
Groups 1 B to 8 B
Unfilled d orbital's or readily produce cations with incompletely filled d orbital's
4-Lanthanides (rare earth elements) and actinides
f- block elements
Incompletely filled f subshells

6. Valence electons: the outermost electrons
Valence electons: the outermost electrons. All nonvalence electrons in an atom are referreed to as core electrons. ns ns
ns np
ns (n-1)d
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-)

7. The designation of A and B groups is not universal.
American designation (A for representative element and B for transition metals).
Europe designation (B for representative element and A for transition metals).
IUPAC has recommended numbering the columns with Arabic numerals (1-18).
The nonsequential numbering of the transition metals in the periodic table (that is, 3B-8B, followed by 1B-2B) acknowledges a correspondence between the outer electron configurations of these elements and those of the representative elements.
Sc and Ga both have three outer electron but they are placed in different groups (3B and 3A) because they are in different types of atomic orbitals.
Zn,Cd,Hg. Elements are often classified as transition metals even though they do not exhibit the characteristics of the transition metals.

8. Worked Example 8.1

9. The element is representative element.
Example 8.1:
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 the element be classified?
Period 3, group 5A
The element is representative element.
(c) Is the element diamagnetic or paramagnetic
Valence electrons
3s p3
paramagnetic

10. Representing Free Elements in Chemical Equations
Chemists always use the empirical formulas to represent metals and metalloids in chemical equations, such as Fe, Na, and B, Si, Ge. (the empirical formulas are the same as the symbols that represent the element).
For nonmetals there is no single rule.
- Carbon, for example, exists in its empirical formula (C) but hydrogen, nitrogen, oxygen, and halogens exist as diatomic molecules, so we use their molecular formulas [H2, N2, O2,and X2 (F2, Cl2, Br2….] in equations.
- The stable form of phosphorus is (P4 )and so we use P4 . for sulfur the stable from is S8, but chemists often use the empirical formula (S) in chemical equations, rather than S8
3. All the noble gases are monoatomic species.
S + O SO2

11. Electron Configurations of Cations and Anions
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]

12. Cations and Anions Of Representative Elements+2 +3 -3 -2 -1 +1
8.2

13. Na+, Al3+, F-, O2-, and N3- are all isoelectronic with Ne.
Na+: [Ne]
Al3+: [Ne]
F-: 1s22s22p6 or [Ne]
O2-: 1s22s22p6 or [Ne]
N3-: 1s22s22p6 or [Ne]
بدون النظر الى التوزيع الالكتروني
فقط بحساب عدد الالكترونات!!
بمعرفة العدد الذري للعنصر
Na (11 e) → Na+ (10 e)
Al (13 e) →Al3+ (10 e)
N (7 e) → N3- (10 e)
F (9 e) → F- (10 e)
O (8 e) → O2- (10 e)
Ne (10 e)
Thus: All are isolelctronic to Ne
Na+, Al3+, F-, O2-, and N3- are all isoelectronic with Ne.
isoelectronic is the species (atoms and ions) have the same number of electrons, and hence the same ground- state electron configuration.
Different isotopes of a particular element contain the same number of electrons.
متساوية الالكترونات

14. Q2: Which of the following species is isoelectronic with Cl-
Q1: What neutral atom is isoelectronic with H- ?
H-: 1s2
same electron configuration as He
Q2: Which of the following species is isoelectronic with Cl-
(a) F-
(b) O2-
(c) K+
(d) Na+
10 e
18 e
10 e
18 e
10 e

15. 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 orbital's. Why?
Because the 3d orbital's is more stable than the 4s orbital in transition metal ions
-The cations for transition metal are not isoelectronic with the preceding noble gases. Why?
Fe: [Ar]4s23d6
Fe2+: [Ar]4s03d6 or [Ar]3d6
Mn: [Ar]4s23d5
Fe3+: [Ar]4s03d5 or [Ar]3d5
Mn2+: [Ar]4s03d5 or [Ar]3d5
Because the transition metals can form more than one cation.

16. Write the electronic configuration for Ni2+ ? (a) [Ar] 4s2 3d5
(b) [Ar] 3d8
(c) [Ar] 4s1 3d6
Ni: [Ar] 4s2 3d8 (transition metal)
→ Ni2+: [Ar] 3d8
Transition metals cations:
First: electrons lost from s orbital
Then: from the (n-1)d orbital

17. 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

18. Effective Nuclear Charge
الشحنة النووية الفعالة: هي الشحنة الموجبة التي تشعر بها الالكترونات الموجودة في تلك الذرة وخاصة في المستوى الأخير للذرة.
The effective nuclear charge (Zeff): is the nuclear charge felt by an electron when both the actual nuclear charge (Z) [that is, the atomic number of the element] and the repulsive effects (shielding) of the other electrons are taken account.
(Zeff) is always less than the actual nuclear charge (Z) present in a nucleus due to shielding effect.
The shielding is a measure of electron-electron repulsions.
Shielding effect increases with the number of inner shells of electrons

19. The periodic table tendency for effective nuclear charge
Increase across a period (due to increasing nuclear charge with no accompanying increase in shielding effect).
Decrease down a group (although nuclear charge increases down a group, shielding effect more than counters its effect).
Increasing Zeff
Decreasing Zeff

20. Atomic Radius
Atomic radius is a term used to describe the size of the atom, but there is no standard definition for this value
نصف قطر التشارك
Atomic radius is one-half (½) the distance between the two nuclei in two adjacent metal atoms (a) or in a diatomic molecule (b).

21. General Trend in Atomic radius
In the same period: the effective nuclear charge increases from left to right → n is the same → the added valence electron is more strongly attracted by the nucleus → the atomic radius decreases from left to right in the period.
In the same group: n increases → atomic radius increases from top to bottom in the group.
Decreasing atomic radius
Increasing atomic radius

22. General Trend in Atomic radius
Decreasing atomic radius
Increasing atomic radius
8.4

23. Atomic Radii

24. Worked Example 8.2

25. N & P are in the same group → N is smaller than P
Example 8.2 p332:
Referring to a periodic table, arrange the following atoms in order of increasing atomic radius: P, Si, N.
Atomic radius decreases
Solution:
N & P are in the same group
→ N is smaller than P
2. P & Si are in the same period
→ P is smaller than Si
The arrangement of increasing atomic radius is:
N < P < Si
Atomic radius increases
الصغير الى الكبير

26. Which choice below correctly lists the elements in order of increasing atomic radii?
A. Na < Mg < K < Rb
B. Mg < Na < K < Rb
C. Rb < K < Na < Mg
D. Rb < K < Mg < Na
Atomic radius decreases
Atomic radius increases

27. Ionic Radius Ionic radius: is the radius of a cation or an anion.
Anions: gain electrons → ionic radius increase because the nuclear charge remain the same but the repulsion resulting from the additional electrons increases the size
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.
(Atom <Anions)
(Cations <Atom)
Cation is always smaller than atom from which it is formed.
Anion is always larger than atom from which it is formed.
Cations <Anions

28. For ions in different groups: they should be isoelectronic
General Trend in Ionic radius
The ionic radius increases from the top to the bottom of the group (like the Atomic radius ).
For ions in different groups: they should be isoelectronic
Isolelectronic ions:
cations < anions: example Na+ < F-
Isolelectronic cations: example Al3+, Mg2+, Na+
Al3+ < Mg2+ < Na+
Isoelectronic anoins: example O2-, F-
F- < O2-
ions generated from the same atom. example Mn2+, Mn3+
Mn3+ < Mn2+
الكاتيونات أصغر من الأنيونات
الكاتيونات: الأصغر ذو الشحنه الموجبه الأكبر
الأنيونات:الأصغر ذو الشحنه السالبه الأصغر
الكاتيون الأصغر ذو الشحنه الموجبه الاكبر

29. Comparison of Atomic Radii with Ionic Radii

30. The Radii (in pm) of Ions of Familiar Elements

32. For each of the following pairs, indicate which one is larger:
Example 8.3 p335:
For each of the following pairs, indicate which one
is larger:
N3- or F-
Mg2+ or Ca2+
Fe2+ or Fe3+
→ isolelctronic anions → F- < N3-
→ in the same group → Mg2+ < Ca2+
→ cations → Fe3+ < Fe2+

33. 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

34. Chemistry in Action: The 3rd Liquid Element?
Variation of physical properties across a period and within a group. From left to right across a period there is a transition from metals to metalloids to nonmetals and within a periodic group the physical properties vary more predictably.
Chemistry in Action: The 3rd Liquid Element?
113 elements, 2 are liquids at 250C – Br2 and Hg
223Fr, t1/2 = 21 minutes
Liquid?

35. Ionization energy are all positive
Ionization energy: is the minimum energy (kJ/mol) required to remove an electron from a gases atom in its ground state.
Atom cation
I1 + X (g) X+(g) + e-
I2 + X+(g) X2+(g) + e-
I3 + X2+(g) X3+(g) + e-
I1 first ionization energy
I2 second ionization energy
I3 third ionization energy
I1 < I2 < I3
Ionization energy are all positive
The higher ionization energy, the more difficult is to remove
the electrons.

37. 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

38. General Trend in First Ionization Energies
Increasing First Ionization Energy
Decreasing First Ionization Energy
8.4

39. Some irregularities (Exceptions) of Ionization Energy
Group 2A (ns2 ) higher than 3A (ns2 np1) in the same period. Example (Be & B)
Group 5A (ns2 np3) higher than 6A (ns2 np4) in the same period. Example (N & O)
(3A < 2A)
(6A < 5A)
1A < 2A < 3A < 4A < 5A < 6A < 7A < 8A X
1A < 3A < 2A < 4A < 6A < 5A < 7A < 8A √
Increasing First Ionization Energy
Decreasing First Ionization Energy

40. Worked Example 8.4

41. 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

42. هي كمية الطاقة الممتصة عند إضافة إلكترون لذرة غازية متعادلة لتكوين أيون غازي بشحنة مقدارها -1. وتصبح شحنتها سالبة عند انطلاق الطاقة.
Electron Affinity
Electron affinity is the negative of the energy change that occurs when an electron is accepted by an atom in the gases state to form an anion.
atom anion
X (g) + e X-(g)
F (g) + e F-(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.

43. General Trend in Electron affinity
Increasing Electron affinity
Decreasing Electron affinity
8.4

44. Electron affinity of metals are generally lower than those nonmetals .
Some irregularities (Exceptions)
Group 2A (ns2 ) lower than 1A (ns1 ) in the same period.
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).
1A < 2A < 3A < 4A < 5A < 6A < 7A < 8A X
8A < 2A < 1A < 3A < 5A < 4A < 6A < 7A √
Increasing Electron affinity
Decreasing Electron affinity

45. >
>

46. Variation of Electron Affinity With Atomic Number (H – Ba)
Has the highest electron Affinity

47. 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

48. Electron Affinity - measurable, Cl is highest
السالبية الكهربائية هي مقياس لمقدرة الذرة أو الجزيء على جذب الإلكترونات في الروابط الكيميائية
Electronegativity
Electronegativity is the ability of an atom to attract toward itself the electrons in a chemical bond.
Electron Affinity - measurable, Cl is highest
X (g) + e X-(g)
Electronegativity - relative, F is highest

49. General Trend in Electronegativity
Increasing Electronegativity
Decreasing Electronegativity

50. Classification of bonds by difference in electronegativity
Bond Type
Covalent
 2
Ionic
0 < and <2
Polar Covalent
Increasing difference in electronegativity
Covalent
share e-
Polar Covalent
partial transfer of e-
Ionic
transfer e-

51. Classify the following bonds as ionic, polar covalent,
or covalent: The bond in CsCl; the bond in H2S; and
the NN bond in H2NNH2.
Cs – 0.7
Cl – 3.0
3.0 – 0.7 = 2.3
Ionic
H – 2.1
S – 2.5
2.5 – 2.1 = 0.4
Polar Covalent
N – 3.0
N – 3.0
3.0 – 3.0 = 0
Covalent
9.5

52. Worked Example 9.2

53. Which choice below correctly lists the elements in order of increasing electronegativity?
C < N < O < F
N < C < O < F
N < C < F < O
C < N < F < O
Increasing Electronegativity
Decreasing Electronegativity

54. Arrange the following Li, Be, B, C, Si, N , S, Ar
in the order of increasing:
Effective nuclear charge
Atomic radius
Ionization energy
Electron affinity
Electronegativity
Li < Be < B , C < Si < N < S < Ar
Ar < S < N < C < Si < B < Be < Li
Li < B < Be < Si < C < S < N < Ar
Ar < Be < Li < B < N < Si < C < S
Li < Be < B , Si < C < N < S < Ar

55. Problems
8.5 – 8.8 – 8.12 – 8.20 – – 8.28 – 8.30 – 8.32
8.36 – 8.38 – 8.40 – 8.44 – 8.46
8.52 – 8.54 – 8.62 – 8.64