1. Unit 2 Section 1 Ionic and Covalent Compounds

2. Unit 2 Section 1 sec. 2. 1 – Ions Sec. 2
Unit 2 Section 1 sec. 2.1 – Ions Sec. 2.2 – Ionic bonds and ionic compounds Sec. 2.3 – naming and writing formulas FOR IONIC COMPOUNDS S

3. Objectives Understand how specific cations and anions form.
Understand how ionic compounds form.
Learn to name ionic compounds.

4. Review Cations/anions
atoms of metals  lose valence electrons  become positively charged
atoms of some nonmetals  gain electrons  become negatively charged

5. Ions and Ionic Bonding
An ionic compound is a compound composed of cations and anions or a metal and a nonmetal.
Although ionic compounds are composed of ions, ionic compounds are electrically neutral.
• Anions and cations have opposite charges and attract one another by means of electrostatic forces.
•The electrostatic forces that hold ions together in ionic compounds are called ionic bonds.

6. The Octet Rule
Octet rule - The electron configuration will replicate a noble gas and form an octet.
Each atom will obtain eight valence e-

7. produce cations with a charge of +1 will lose 1 v.e.-
Octet Rule
Group 1A metals have:
1 valence electron
produce cations with a charge of +1
will lose 1 v.e.-
Example: Li loses 1 valence electron to become Li+1

8. produce cations with a charge of +2 will lose 2 v.e.-
Octet Rule
Group 2A metals have:
2 valence electron
produce cations with a charge of +2
will lose 2 v.e.-
Example: Mg loses 2 valence electrons to become Mg+2

9. Formation of Cations
•The figure at right lists the symbols of the cations formed by metals in Groups 1 and 2.
•Cations of Group 1 elements always have a charge of 1+.
•Cations of Group 2 elements always have a charge of 2+.

10. Anions  atoms of some nonmetals  gain electrons become negatively charged
Electron configuration will follow octet rule

11. produce anions with a charge of -1 will gain 1 v.e.-
Octet Rule
Group 17 / 7A metals have:
7 valence electrons
produce anions with a charge of -1
will gain 1 v.e.-
Example: F gains 1 valence electron to become F-1

12. produce anions with a charge of -2 will gain 2 v.e.-
Group 16 / 6A metals have:
6 valence electrons
produce anions with a charge of -2
will gain 2 v.e.-
Example: O gains 2 valence electrons to become O-2

13. Formation of Anions
Atoms of nonmetals and metalloids form anions by gaining enough valence electrons to attain an octet.

15. Ionic Bonding
•The forces that hold cations and anions together in ionic compounds are called ionic bonds.
The chemical formula of an ionic compound is known as a formula unit.
A formula unit is the lowest whole-number ratio of ions in an ionic compound
Video – Forming ionic bonds

16. Ionic Bonding
Na + Cl Rb + F Ca + Br

17. You Try
Write the formula for the elements that combine by balancing out the charges. (Get a net charge of zero)
Ra I
K O

18. You Try
Write the formula for the elements that combine by balancing out the charges. (Get a net charge of zero)
Ca I
K P

19. Binary Compounds
Binary compounds are made up of only 2 different elements
There can be more than 2 or more atoms though
NaCl
K2O
Al2S3

20. To name a binary ionic compound:
Write the name of the cation first (always a metal)
Write the name of the anion, but change the ending to –ide
Note that any subscripts do not change the name
NaCl
sodium
chlorine → chloride
sodium chloride

21. type i Binary Ionic compounds Chemical Naming
K2O Al2S3 Ca3P2
Please do together as a class.
Potassium oxide.
Aluminum sulfide

22. WRITING FORMULAS FROM NAME
When charges are not balanced, it is necessary to add subscripts
They represent the quantity of each element
No subscript equals 1 atom
Li+1O2- the charges are not equal
There is only one positive and two negatives
We need another positive charge to make them equal
Li2O +1 -2

23. Writing Formulas
Sodium chloride  Radium arsenide Aluminum selenide 

24. You try
Lithium bromide Calcium chloride Gallium oxide Lithium nitride

25. Polyatomic ions are ions that contain more than one atom
Examples:
(SO4)2-
(OH)-
(PO4)3-
(NH4)+
It is important to note that the charge is distributed throughout all the atoms in the ion
Not only on the last atom

27. Name the following ionic compounds containing polyatomic ions
Li2SO4 NaNO3 SrCO3 MgSO4 NH4Cl

28. YOU TRY

29. Naming Ionic compounds containing transition metals

30. Periodic Chart of ions

31. Type II Binary Ionic Compounds
Contain Metal Cation + Nonmetal Anion
Transition metals can have multiple charges
For example iron can be either Fe2+ or Fe3+
To name compound with transition metal  add Roman Numeral in parentheses to indicate metal’s charge.
First determine charge of anion first
Then, determine charge of metal
Nonmetal anion named by changing the ending on the nonmetal name to -ide
Copyright©2004 by Houghton Mifflin Company. All rights reserved. 8

32. Copyright©2004 by Houghton Mifflin Company. All rights reserved.

33. Write the formula for compounds containing a transition metal
cobalt (III) chloride
cobalt(II) chloride
Iron (III) oxide
Chromium (II) phosphide
lead (II) sulfide
Titanium (III) selenide
CoCl3
CoCl2
Fe2O3
Cr3P2
PbS
Ti2Se3
Copyright©2004 by Houghton Mifflin Company. All rights reserved.

34. Write the name of the ionic compound containing a transition metal
Systematic Name
CuO
Cu2O
Fe2S3
FeS
PbCl2
PbCl4
Hg2Se
copper (II) oxide
copper (I) oxide
iron (III) sulfide
iron (II) sulfide
lead (II) chloride
lead (IV) chloride
mercury (II) selenide
Copyright©2004 by Houghton Mifflin Company. All rights reserved.

35. Review Type I Type I CaBr2 6. Strontium phosphide Li2O Type II Type II
Name the following compounds. Write Formulas.
Type I Type I
CaBr Strontium phosphide
Li2O
Type II Type II
3. CuBr titanium (III) sulfide
4. CoCl3
5. Fe3As2

36. Review CaBr2 6. Strontium phosphide Li2O
Name the following compounds. Write Formulas.
Type I Type I
CaBr Strontium phosphide
Li2O
Polyatomics Polyatomics
3. (NH4)3(PO3) Barium nitrate
Type II Type II
4. CuBr titanium (III) sulfide
5. Fe3As2

37. Review KEY Calcium bromide Lithium oxide Ammonium phosphate
Name the following compounds.
Type I
CaBr2
Li2O
Polyatomics
3. (NH4)3(PO4)
Type II
4. Fe3As2
5. CuBr
KEY
Calcium bromide
Lithium oxide
Ammonium phosphate
Iron(II) arsenide
Copper (I) bromide

38. Review
Write Formulas. Type I 6. Strontium phosphide Polyatomics 9. Barium nitrate Type II 10. titanium (III) sulfide
KEY
Sr3P2
Ba(NO3)2
Ti2S3 +2 -3 +2 -1 +3 -2

39. Review CaBr2 7. Strontium phosphide Li2O 8. Aluminum selenide
Name the following compounds. Write Formulas.
Type I Type I
CaBr Strontium phosphide
Li2O Aluminum selenide
Polyatomics Polyatomics
3. MgSO Barium nitrate
(NH4)3(PO3)
Type II Type II
5. Fe3As titanium (III) sulfide
6. CuBr

40. Review KEY Calcium bromide Lithium oxide Magnesium sulfate
Name the following compounds.
Type I
CaBr2
Li2O
Polyatomics
3. MgSO4
(NH4)3(PO3)
Type II
5. Fe3As2
6. CuBr
KEY
Calcium bromide
Lithium oxide
Magnesium sulfate
Ammonium phosphite
Iron(II) arsenide
Copper (I) bromide

41. Review
Write Formulas. Type I 7. Strontium phosphide 8. Aluminum selenide Polyatomics 9. Barium nitrate Type II 10. titanium (III) sulfide
KEY
Sr3P2
Al2Se3
Ba(NO3)2
Ti2S3 +2 -3 +3 -2 +2 -1 +3 -2

42. Covalent Compounds sec. 2. 4 – MOLECULAR COMPOUNDS Sec. 2
Covalent Compounds sec. 2.4 – MOLECULAR COMPOUNDS Sec. 2.5 – naming and writing formulas FOR MOLECULAR COMPOUNDS

44. We learned that atoms can give up or accept electrons to form ions.
Previous Chapter
We learned that atoms can give up or accept electrons to form ions.
These ions combine to form ionic compounds
Recall that ionic bonds form when the combining atoms give up or accept electrons.
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

45. Covalent (Molecular) Compounds
Sharing Electrons
- Another way that atoms can combine is by sharing electrons.
To form covalent compounds
Atoms that are held together by sharing electrons are joined by a covalent bond.
Two or more nonmetals form covalent compounds
Recall that ionic bonds form when the combining atoms give up or accept electrons.
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

46. Covalent Bonding
A molecule is a neutral group of atoms joined together by covalent bonds.
Some molecules are made up of the same element
Examples: O2 , F2 , Cl2

47. What is an octet. An atom/element that has 8 valence electrons
What is an octet? An atom/element that has 8 valence electrons. What is the octet rule? An element will have 8 valence electrons around itself in a compound

48. Predicting Covalent Bonds in Molecular Compounds Using Molecular Formulas
In covalent bonds, electron sharing usually occurs so that atoms attain the electron configurations of noble gases.
The octet rule states that chemical compounds form so each atom will have 8 valence electrons
Exception: atoms trying to be like helium
The octet rule states that chemical compounds form so each atom (through gaining, losing, or sharing electrons) will have 8 valence electrons

49. We use Lewis Dot Diagrams to show covalent bonding

50. In the F2 molecule, each fluorine atom contributes one electron to complete the octet.
Two fluorine atoms share only one pair of valence electrons. That is a single covalent bond.
*When we show the bonding, we use Lewis structures
Notice that the two fluorine atoms share only one pair of valence electrons.
When we show the bonding, we use Lewis structures
Structural formulas are a neater way to show bonding

51. In F2, each fluorine atom has three unshared pairs of electrons.
A pair of valence electrons that is not shared between atoms is called an unshared pair, also known as a lone pair
In F2, each fluorine atom has three unshared pairs of electrons.
Unshared pair of electrons

52. The Octet Rule in Covalent Bonding
Single Covalent Bonds
Hydrogen gas (H2) atoms share only one pair of electrons, forming a single covalent bond.
Hydrogen gas consists of diatomic molecules whose atoms share only one pair of electrons, forming a single covalent bond. The Octet Rule in Covalent Bonding

53. FORMING MOLECULAR COMPOUNDS
Hydrogen and oxygen carbon and hydrogen
oxygen gas

54. Do now Ionic compound ______ 1. Shares electrons Covalent compound
______2. electrons are gained and lost

55. 9.3 Naming Covalent Compounds
Contain only nonmetals
Known as covalent (molecular) compounds
Copyright©2004 by Houghton Mifflin Company. All rights reserved.

56. Copyright©2004 by Houghton Mifflin Company. All rights reserved.

57. Naming Covalent Compounds10

58. Examples carbon dioxide carbon monoxide boron trifluoride
dinitrogen pentoxide
nitrogen monoxide
carbon tetrachloride
triphosphorus pentoxide
CO2 CO
BF3
N2O5 NO
CCl4
P3O5
Copyright©2004 by Houghton Mifflin Company. All rights reserved.

59. Write the formula Nitrogen dioxide Phosphorus trichloride
Sulfur monoxide
Dicarbon hexachloride
Boron pentafluoride

60. Copyright©2004 by Houghton Mifflin Company. All rights reserved.

61. Properties of Ionic compounds
Most ionic compounds are crystalline solids at room temperature.
The component ions in such crystals are arranged in repeating three-dimensional patterns.

62. Comparing Molecular and Ionic Compounds
Water, which is a molecular compound, and sodium chloride, which is an ionic compound, are compared here.
Array of
sodium ions and
chloride ions
Collection of
water molecules
Formula unit of
sodium chloride
Molecule of
water
Chemical formula
H2O
NaCl
Chemical formula

63. Intermolecular Attractions and Molecular Properties
Comparing Ionic compounds and Molecular Compounds
This table summarizes some of the characteristic differences between ionic and covalent (molecular) substances.
Characteristics of Ionic and Molecular Compounds
Characteristic
Ionic Compound
Molecular Compound
Bond formation
Transfer of one or more electrons between atoms
Sharing of electron parts between atoms
Type of elements
Metallic and nonmetallic
Nonmetallic
Physical state
Solid
Solid, liquid, or gas
Melting point
High (usually above 300°C)
High (usually below 300°C)
Solubility in water
Usually high
High to low
Electrical conductivity of aqueous solution
Good conductor
Poor to nonconducting
Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.