1. Chapter 22
Chemical Bonds

2. 22.1 Stability in Bonding
Most elements are found combined with other elements because they are not chemically stable (compounds)
Noble gases are mono-atomic (6% elements)
Chemical stability depends on valence electrons
Compounds have different properties than the elements that compose it
Ex. Na, Cl, NaCl from chapter 18

3. Writing Chemical Formulas
Chemical Formula: represents a chemical compound
Uses symbols for the elements
The subscript numbers show the ratio of ions in the compound
Formulas are like cooking recipes

4. Write the Formula For: Sodium chloride Magnesium oxide Aluminum oxide
Iron (III) oxide
Calcium fluoride
Strontium phosphate
Barium nitrate

5. Write the Name for: K2O Al2O3 Mg3N2 CaCO3 NaNO3
Calculate the molecular weight for each of the above:

6. Stable Electron Configurations
When outermost energy level is full - Atom is stable (pg. 690)
Not likely to react with other elements
Electron dot diagram – model of atom with symbol of element in the center and the valence electrons represented by dots around the symbol
Pg. 690, 691

7. Atmospheric gases exist as molecules
Chemical bonding occurs when elements bond with other elements or themselves to achieve stability in their valence levels
Atmospheric gases exist as molecules
Hydrogen H2
Oxygen O2
Nitrogen N2
Chlorine Cl2

8. Ionic Bonds Metals combine with Nonmetals
Transfer of electrons to become more stable
Ions – when an atom gains or loses electrons “charged atom”
Electrons no longer equal the protons – the atom becomes charged
Draw NaCl, MgO, Al2O3

9. Anions and Cations
Loses electrons – makes positive ion or cation – Ex. Na+ sodium ion
“metals”
Gains electrons – makes negative ion or anion – add suffix -ide Ex. Cl- chloride ion
“nonmetals”
Ionic bond – force that holds anions and cations together

10. Ionic bond: formed when electrons are transferred from one atom to another
Ionization Energy: – energy required to remove an electron
Ionic Compounds: – Compounds that contain ionic bonds
Chemical Formula: – shows the elements and ratio of atoms in a compound
Crystal Lattices: – arrangement of ions in a repeating pattern – forms solid crystals

11. 6.2 Covalent Bonding Nonmetals combine with nonmetals
Sharing electrons to become stable
Covalent Bond – when two atoms share one pair of valence electrons – single bond
Two pairs – double bond
Three pairs – triple bond

12. Polar Covalent Bonds Electrons are not shared equally
Atom with greater attraction for electrons has a partial negative charge
Other atom has a partial positive charge
Ex. Water – H2O
Ex. Carbon Dioxide – CO2

13. Polyatomic Ions – a group of covalently bonded atoms with a positive or negative charge and acts as a unit
Prefix poly- means “many”
Most polyatomic ions are anions
Page 707

14. 6.3 Naming Compounds and Writing Formulas
Chemical Formula: represents a chemical compound
Uses symbols for the elements
The subscript numbers show the ratio of ions in the compound

15. Ionic Compounds
Write symbol of cation (metal) first followed by the symbol of the anion (nonmetal) Ex. NaCl
Use subscripts to show the ratio
Criss cross the oxidation numbers
Add the suffix “ide” to the nonmetal when naming these

16. Covalent compounds
Name and formula describe the type and number of atoms in each molecule
Prefixes on page 709
Use prefixes to tell how many atoms of each element Ex. N2O4
dinitrogen tetraoxide

17. 6.4 The Structure of Metals
Metallic Bond – the attraction between a metal cation and the shared electrons that surround it
The more valence electrons in the shared pool, the stronger the metallic bond

18. Alloys
A mixture of 2 or more elements, one of which is a metal – has properties of both metals
Copper Alloys – copper + tin = bronze
copper + zinc = brass
Steel Alloys – iron + carbon = steel
iron + chromium = stainless steel