1. Chapter 7 and 8: Ionic and Metallic Bonding Covalent Bonding Ions, Ionic Bonds and Compounds, Bonding in Metals, Molecular Compounds and Polar Bonds and Molecules

2. You will learn about ionic, covalent and polar covalent bonds.

3. Valence Electrons Valence electrons are the electrons in the outermost energy level. The group number equals the number of valence electrons the atom contains. An electron dot structure shows the symbol of the elements and its valence electrons. You will learn about ionic, covalent and polar covalent bonds.

4. Ionic Compounds An ionic compound is made up of cations (metals) and anions (nonmetals) and neutral in charge. –Anion names end in - ide A representative unit of an ionic compound is its formula unit –ions in the compound written in the simplest whole number ratio. You will learn about ionic, covalent and polar covalent bonds.

5. Examples For each element below, state the number of valence electrons in the atom, the electron dot structure, and the chemical symbol for the most stable ion 1. Ba 2. I 3. K Give the name and symbol of the ion formed when 1. A chlorine atom gains one electron 2. A potassium atom loses one electron 3. An oxygen atom gains two electrons 4. A barium atom loses two electrons You will learn about ionic, covalent and polar covalent bonds.

6. Examples Which of these combinations of elements are most likely to react to form ionic compounds? Predict the formula of the ionic compound, if formed 1. Sodium and magnesium 2. Barium and sulfur 3. Potassium and iodine 4. Oxygen and argon You will learn about ionic, covalent and polar covalent bonds.

7. Ionic Compounds Most ionic compounds are crystalline solids at room temperature. High melting points because ions have strong attraction for one another Conduct an electric current when melted or in an aqueous solution because ions free to move You will learn about ionic, covalent and polar covalent bonds.

8. Molecular Compounds Electrons are shared Atoms held together by covalent bonds Solids w/all atoms covalently bonded is a network solid Can be represented by molecular formulas which describe the combination of atoms Lower melting and boiling points than ionic compounds You will learn about ionic, covalent and polar covalent bonds.

9. Examples Classify each of the following as an atom or a molecule. 1. Be 2. CO 2 3. N 2 4. H 2 O 5. Ne You will learn about ionic, covalent and polar covalent bonds.

10. Electronegativity Electronegativity is the ability of an atom to attract shared electrons to itself. It is a property that describes polar covalent bonds. Electronegativity is used to determine bond polarity. You will learn about ionic, covalent and polar covalent bonds.

11. Electronegativity The trend for electronegativity is the same as ionization energy. You will learn about ionic, covalent and polar covalent bonds.

12. Electronegativity The chart below shows electronegativity values associated with each element. The difference of the values in a bond corresponds to a specific type of bond polarity (ionic, covalent or polar covalent). You will learn about ionic, covalent and polar covalent bonds.

13. Polar Covalent Bonding and Dipoles Electrons are shared unequally in polar covalent bonds Dipole interactions occur between polar molecules Atom with higher electronegativity “hogs” electrons of polar covalent bond. If polar bonds cancel, molecule is nonpolar (will discuss w/Lewis structures) You will learn about ionic, covalent and polar covalent bonds.

14. Dipole moments Some examples: H-ClCOBr-Brnone You will understand the nature of bonds and their relationship to electronegativity.

15. Bond Polarity Based on electronegativity differences, there is a general rule of thumb to determine the type of polarity occurring: 0 – 0.4 = nonpolar covalent 0.4 – 1.0 = moderately polar covalent 1.0 – 2.0 = very polar covalent ≥ 2.0 = ionic You will learn about ionic, covalent and polar covalent bonds.

16. Examples H 2 2.1-2.1 = 0nonpolar covalent HCl3.0-2.1 = 0.9moderately polar covalent HF4.0 – 2.1 = 1.9very polar covalent NaCl4.0-1.0 = 3.0ionic You will learn about ionic, covalent and polar covalent bonds.

17. Examples What type of bond – nonpolar covalent, polar covalent or ionic – will form between each pair of atoms? 1. Na and O 2. O and O 3. P and O Which would you expect to have the higher melting point, CaO or CS 2 ? You will learn about ionic, covalent and polar covalent bonds.

18. Recap What is the difference between ionic, covalent and polar covalent bonds? What is electronegativity? What is the trend for it on the periodic table? What atom is most electronegative? What is the nature of bonds related to electronegativity? You will learn about ionic, covalent and polar covalent bonds. You will understand the nature of bonds and their relationship to electronegativity.

19. Homework Bring for lab: 1.A water bottle 2.Alka seltzer tablets 3.Vegetable oil You will learn about ionic, covalent and polar covalent bonds.