1. Chapter 6: Ionic Bonds and Some Main-Group Chemistry
4/8/2019
Copyright © 2008 Pearson Prentice Hall, Inc.

2. 12.1 Types of Chemical Bonds
Bonds: a force that holds groups of two or more atoms together and makes them function as a unit
Required 2 e- to make a bond
Bond energy: amount of energy required to form or to break the bond

3. Ionic Bonding Occurs in ionic compound
Results from transferring electron
Created a strong attraction among the closely pack compound

4. Ions and Their Electron Configurations
Chapter 6: Ionic Bonds and Some Main-Group Chemistry
4/8/2019
Ions and Their Electron Configurations
Atoms
Ions N: O: F:
Na:
Mg:
Al:
1s2 2s2 2p3
1s2 2s2 2p4
1s2 2s2 2p5
1s2 2s2 2p6 3s1
1s2 2s2 2p6 3s2
1s2 2s2 2p6 3s2 3p1
+ 3 e-
+ 2 e-
+ 1 e-
- 1 e-
- 2 e-
- 3 e-
N3-:
O2-:
F1-:
Ne:
Na1+:
Mg2+:
Al3+:
1s2 2s2 2p6
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5. Ions and Their Electron Configurations
Chapter 6: Ionic Bonds and Some Main-Group Chemistry
Ions and Their Electron Configurations
4/8/2019
Copyright © 2008 Pearson Prentice Hall, Inc.

6. Ions and Their Electron Configurations
Chapter 6: Ionic Bonds and Some Main-Group Chemistry
4/8/2019
Ions and Their Electron Configurations
Atoms
Ions
Fe:
[Ar] 4s2 3d6
- 2 e-
- 3 e-
Fe2+:
Fe3+:
[Ar] 3d6
[Ar] 3d5
It’s not a simple reverse of the process when discussing ions. It’s the configuration of the ion that’s important to consider and the energy levels have a different arrangement in the ions.
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7. Chapter 6: Ionic Bonds and Some Main-Group Chemistry
4/8/2019
Ionic Radii
Effective nuclear charge.
Copyright © 2008 Pearson Prentice Hall, Inc.

8. Chapter 6: Ionic Bonds and Some Main-Group Chemistry
4/8/2019
Ionic Radii
Effective nuclear charge.
Copyright © 2008 Pearson Prentice Hall, Inc.

9. Chapter 6: Ionic Bonds and Some Main-Group Chemistry
4/8/2019
Ionization Energy
Ionization Energy (Ei): The amount of energy necessary to remove the highest-energy electron from an isolated neutral atom in the gaseous state.
Students sometimes mistakenly equate ionization energy to the amount of energy required to form an ion.
Copyright © 2008 Pearson Prentice Hall, Inc.

10. Chapter 6: Ionic Bonds and Some Main-Group Chemistry
Ionization Energy
4/8/2019
Note the periodicity of the first ionization energies.
Copyright © 2008 Pearson Prentice Hall, Inc.

11. Chapter 6: Ionic Bonds and Some Main-Group Chemistry
Ionization Energy
4/8/2019
Boron has a lower Ei due to a smaller Zeff
(shielding by the 2s electrons)
Copyright © 2008 Pearson Prentice Hall, Inc.

12. Chapter 6: Ionic Bonds and Some Main-Group Chemistry
4/8/2019
Ionization Energy
Oxygen has a lower Ei since the first electron is removed from a filled orbital
Copyright © 2008 Pearson Prentice Hall, Inc.

13. Higher Ionization Energies
Chapter 6: Ionic Bonds and Some Main-Group Chemistry
4/8/2019
Higher Ionization Energies
M1+ + e-
M + energy
M2+ + e-
M1+ + energy
M3+ + e-
M2+ + energy
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14. Chapter 6: Ionic Bonds and Some Main-Group Chemistry
4/8/2019
Electron Affinity
Electron Affinity (Eea): The energy released when a neutral atom gains an electron to form an anion.
Books use different conventions. The one this book uses assigns a negative sign to electron affinity.
Copyright © 2008 Pearson Prentice Hall, Inc.

15. Ionic Bonds and the Formation of Ionic Solids
Chapter 6: Ionic Bonds and Some Main-Group Chemistry
4/8/2019
Ionic Bonds and the Formation of Ionic Solids
1s2 2s2 2p6
3s1
1s2 2s2 2p6 3s2
3p5 Na + Cl
Na1+
Cl1-
A transfer of electrons from the metal to the nonmetal.
1s2 2s2 2p6
1s2 2s2 2p6 3s2 3p6
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16. Chapter 6: Ionic Bonds and Some Main-Group Chemistry
4/8/2019
Copyright © 2008 Pearson Prentice Hall, Inc.

17. Chapter 6: Ionic Bonds and Some Main-Group Chemistry
4/8/2019
The Octet Rule
Octet Rule: Main-group elements tend to undergo reactions that leave them with eight outer-shell electrons.
Copyright © 2008 Pearson Prentice Hall, Inc.

18. Chapter 6: Ionic Bonds and Some Main-Group Chemistry
The Octet Rule
4/8/2019
Octet Rule: Main-group elements tend to undergo reactions that leave them with eight outer-shell electrons.
Metals tend to have low Ei and low Eea.
They tend to lose one or more electrons.
Nonmetals tend to have high Ei and high Eea.
They tend to gain one or more electrons.
Copyright © 2008 Pearson Prentice Hall, Inc.

19. Chapter 6: Ionic Bonds and Some Main-Group Chemistry
4/8/2019
The Octet Rule
This is important in Lewis structures and molecular shapes.
Copyright © 2008 Pearson Prentice Hall, Inc.

20. Covalent Bond and Molecular Structure
Chapter 7
Covalent Bond and Molecular Structure

21. Chapter 7: Covalent Bonds and Molecular Structure
4/8/2019
The Covalent Bond
Covalent Bond: A bond that results from the sharing of electrons between atoms.
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22. Chapter 7: Covalent Bonds and Molecular Structure
4/8/2019
Copyright © 2008 Pearson Prentice Hall, Inc.

23. Polar Covalent Bonds: Electronegativity
Chapter 7: Covalent Bonds and Molecular Structure
4/8/2019
Polar Covalent Bonds: Electronegativity
Electronegativity: The ability of an atom in a molecule to attract the shared electrons in a covalent bond.
Copyright © 2008 Pearson Prentice Hall, Inc.

24. Polar Covalent Bonds: Electronegativity
Chapter 7: Covalent Bonds and Molecular Structure
4/8/2019
Polar Covalent Bonds: Electronegativity
NaCl
Cl2
HCl
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25. Polar Covalent Bonds: Electronegativity
Chapter 7: Covalent Bonds and Molecular Structure
4/8/2019
Polar Covalent Bonds: Electronegativity
Copyright © 2008 Pearson Prentice Hall, Inc.

26. Polarity
Polar covalent bonds – the bonding electrons are attracted somewhat more strongly by one atom in a bond
Electrons are not completely transferred
More electronegative atom: δ- . (δ represents the partial negative charge formed)
Less electronegative atom: δ+

27. Relationship Between Electronegativity and Bond Type
Predicting bond polarity
Atoms with similar electronegativity (Δ EN <0.4) –form nonpolar bond
Atoms whose electronegativity differ by more than two (Δ EN > 2) – form ionic bonds
Atoms whose electronegativity differ by less than two (Δ EN < 2) – form polar covalent bonds

28. Polarity and Dipole Moment
a vector quantity from the center of the positive charge to the center of negative charge
Represents with an arrow
E.g Draw the dipole moment for HF, H2O, HCl, OF

29. Examples
For each of the following pairs of bonds, choose the bond that will be more polar
a. H-P, H-C b. N-O, S-O

30. Lewis Structures
represents how an atom’s valence electrons are distributed in a molecule
Show the bonding involves (the maximum bonds can be made)
Try to achieve the noble gas configuration

31. Examples Draw Dot Lewis structure for the following atoms: Na Mg C SCo
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32. Rules Duet Rule: sharing of 2 electrons
E.g H2
H : H
Octet Rule: sharing of 8 electrons
Carbon, oxygen, nitrogen and fluorine always obey this rule in a stable molecule
E.g F2, O2
Bonding pair: two of which are shared with other atoms
Lone pair or nonbonding pair: those that are not used for bonding

33. Electron-Dot Structures
Chapter 7: Covalent Bonds and Molecular Structure
4/8/2019
Electron-Dot Structures
Think of this section as an introduction. It is much easier to write electron-dot structures using the rules listed in the next section.
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34. Electron-Dot Structures
Chapter 7: Covalent Bonds and Molecular Structure
4/8/2019
Electron-Dot Structures
We have single, double, and triple bonds.
Copyright © 2008 Pearson Prentice Hall, Inc.

35. Rules for Wring Dot Lewis structure
Step 1: Calculate the total number of valence electrons of all atoms in the molecule
Step 2: Create a skeletal structure using the following rules:
Hydrogen atoms (if present) are always on the “outside” of the structure. They form only one bond
The central atom is usually least electronegative. It is also often unique (i.e,. the only one atom of the element in the molecule). Remember, there might be no “central” atom.
Connect bonded atoms by line (2-electron, covalent bonds

36. Rules
Step 3: Place lone pairs around outer atoms (except hydrogen) so that each atom has an octet
Step 4: Calculate the number of electrons you haven’t used. Subtract the number of electrons used so far, including electrons in lone pair and bonding pairs, from the total in Step 1. Assign any remaining electrons to the central atom as lone pair

37. Rules
Step 5: If the central atom is B (boron) or Be (beryllium), skip this step
If the central atom has an octet after step 4, skip this step
If the central atom has only 6 electrons, move a lone pair from an outer atom to form a double bond between outer atom and the central atom
If the central atom has only 4 electrons, do Step 5a to two different outer atoms (i.e, form two double bonds) or twice to one outer atom (i.e., form one triple bond)

38. Electron-Dot Structures of Polyatomic Molecules
Chapter 7: Covalent Bonds and Molecular Structure
4/8/2019
Electron-Dot Structures of Polyatomic Molecules
Draw an electron-dot structure for CF4.
Step 1:
Total valence electrons
Step 2:
Draw its skeletal
Step 2: The positioning of the terminal atoms about the central is not critical as long as they simply surround the central atom.
Step 3: The terminal atom is hydrogen.
Step 5: The central atom has an octet so no multiple bonding.
Step 4: Dot Lewis structure
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39. Examples Give the Lewis structure for the following H2O ClO4- CO2 NH3
NO3-,