1. Chapter 7: Ionic Compounds and Metals
Mr. Stripling
Pre-AP Chemistry
Room 402

2. Ion Formation
Valence electrons are involved in the formation of chemical bonds between two atoms.
Chemical Bond – force that holds two atoms together
Chemical bonds form by:
Attraction between the positive nucleus of one atom and the negative electrons of another atom
The attraction between positive ions and negative ions

3. Valence Electrons
Electron-dot structures are used to keep track of valence electrons
They are also useful in illustrating chemical bonds

4. Review Ionization Energy – how easily an atom loses an electron
Electron Affinity – how much attraction an atom has for electrons
Reactivity depends on the number of valence electrons
Elements tend to react in order to acquire the stable electron configurations of noble gases

5. Positive Ion Formation
Occurs when an atom loses one or more valence electrons
Positively charged ions are called cations

6. Ne: 1s22s22p6
Na: 1s22s22p63s1
When Na loses its valence electron its electron configuration becomes identical to Ne
Na gains a stable electron configuration
Na DOES NOT BECOME Ne
Na is a sodium ion with a single positive charge

7. Metal Ions Reactive because they lose valence electrons easily
Groups 1 and 2 metals are the most reactive metals
Some group 13 atoms also form ions

8. Transition Metal Ions Have an outer energy level of ns2
Form 2+ ions when forming positive ions
d electrons can also be lost, making it possible for transition metals to form ions of 3+ or greater
Difficult to predict the number of electrons that will be lost
Fe forms both Fe2+ and Fe3+ ions

9. Pseudo-Noble Gas Configurations
Electron configurations other that the noble gas notation can provide stability
Elements in groups lose electrons to form an outer energy level containing full s, p, and d sublevels

10. Negative Ion Formation
Nonmetals, on the right side of the table, easily gain electrons to attain a stable outer electron configuration
Gaining electrons forms anions, negatively charged ions
To designate an anion, the ending –ide is added to the root name of the element
Chlorine atom -> chloride anion

11. Nonmetal Ions
Nonmetals gain valence electrons in order to have a total of 8
Some nonmetals can lose OR gain electrons to form an octet
Phosphorus can lose five or gain three valence electrons to form an octet
In general, group elements gain valence electrons to form an octet

13. Formation of an Ionic Bond
Ionic Bond – the electrostatic force that holds oppositely charged particles together in an ionic compound
Ionic compounds – compounds that contain ionic bonds.
Ionic bonds that occur between metals and oxygen form an oxide ion

14. Binary Ionic Compounds
Compounds that ONLY contain TWO different elements
Part metallic cation, part nonmetallic anion
Examples:
Sodium chloride (NaCl)
Magnesium oxide (MgO)

15. Compound Formation & Charge
Ca: [Ar] 4s2 Needs to lose 2 electrons to be stable
F: [He] 2s22p5 Must gain 1 electron for stability
Number of electrons lost and gained must be equal
2 F atoms need to accept the 2 electrons from the Ca atom
Yields calcium fluoride (CaF2)

16. Aluminum oxide (Al2O3)
Aluminum loses 3 electrons
Oxygen atoms gain 2 electrons
3 oxygen atoms are needed to accept six electrons lost by 2 aluminum atoms

17. Properties of Ionic Compounds
Chemical bonds determine properties of compounds
Carpet, ceramics/glass, glossy paper, toothpaste
Strong attraction among positive and negative ions in an ionic compound forms a crystal lattice
Crystal lattice
a three-dimensional geometric arrangement of particles
Each positive ion is surrounded by negative ions and each negative ion is surrounded by positive ions

18. Physical Properties
MP, BP, and hardness are physical properties that depend on how strong particles that make compounds are attracted to one another
Electrical conduction depends on availability of free moving charged particles
Ionic solids don’t conduct electricity
Ionic liquids do
An ionic compound whose aqueous solution conducts an electric current is an electrolyte

19. Ionic bonds are relatively strong
Ionic crystals require a large amount of energy to be broken
Ionic crystals have high melting and boiling points

20. Energy and the Ionic Bond
Every chemical reaction absorbs or releases energy
Endothermic reaction – energy is absorbed
Exothermic reaction – energy is released
Ionic compound formation is always exothermic

21. Lattice Energy
Energy required to separate 1 mole of ions of an ionic compound
Strength of the forces holding ions in place
Directly related to the size of the ions bonded

22. Classwork Problems 7-11 on page 212
Problems 1 & 2 (Chapter 7) on page 980
Only write the formula units

23. Formulas for Ionic Compounds
Formula Unit – the chemical formula for an ionic compound represent the simplest ratio of the ions involved
MgCl2 – magnesium and chloride ions exist in a 1:2 ratio
Contains one Mg2+ ion and two Cl- ions for a total charge of zero
Mg2+ and Cl- are monatomic ions – one-atom ions

24. Oxidation Numbers
Charge of a monatomic ion equals its oxidation number or oxidation state
Equals the number of electrons transferred from the atom for an ion
Example:
Sodium atom transfers one electron to a chlorine atom to form sodium chloride
Na+ and Cl-
Sodium oxidation number = 1+
Chlorine oxidation number = 1-

25. Formulas for Binary Ionic Compounds
Symbols for cation is always written first, followed by the symbol of the anion
Subscripts
Small numbers to the lower right of a symbol
Represent the number of ions of each element in an ionic compound
If there is no subscript, assumed to be 1
Oxidation numbers are used to write formulas for ionic compounds

26. Formulas for Polyatomic Ionic Compounds
Polyatomic ion – ions made up of more than one atom
Act as individual ions
Charge applies to the entire group of atoms
Act as a unit, so the change the subscripts of the atoms within ions
Ammonium ion (NH4+) and oxide ion (O2-)
(NH4)2O

27. Naming an Oxyanion
Oxyanion – a polyatomic ion composed of an element (usually nonmetal) bonded to one or more oxygen atoms

28. Oxyanion Naming Conventions for Sulfur and Nitrogen
Identify the ion with the greatest number of oxygen atoms. This ion is named using the root of the nonmetal and the suffix –ate
Identify the ion with fewer oxygen atoms. This ion is named using the root of the nonmetal and the suffix -ite
Examples:
NO3- nitrate NO2- nitrite
SO42- sulfate SO32- sulfite

29. Oxyanion Naming Convention for Chlorine
The oxyanion with the greatest number of oxygen atoms is named using the prefix per-, the root of the nonmetal and the suffix –ate
The oxyanion with one fewer oxygen atom is named using the root of the nonmetal and the suffix –ate
The oxyanion with two fewer oxygen atoms is named using the root of the nonmetal and the suffix –ite
The oxyanion with three fewer oxygen atoms is named using the prefix hypo-, the root of the nonmetal, and the suffix -ite

30. Classwork Problems 19-22 on page 221 Problems 24-26 on page 222

31. Read Page 226