1. Chapter 6 – Chemical Bonds

2. 6.1 Ionic Bonding
When the highest occupied energy level of an atom is filled with electrons, the atom is stable and not likely to react.
Electron dot diagram – symbol represents the nucleus and each dot represents a valence electron (also called Lewis Dot Diagram or Lewis Dot Structure)

4. Ionic Bonds
Elements achieve stable e- config. through the transfer of e-
Form between a metal and a nonmetal
Metal gives up e-; nonmetal gains e-
Ions (atoms with charges) are formed
Metal becomes + ion, nonmetal becomes a neg. ion
Opposite charges attract each other

5. Sodium Chloride

6. Chemical bond – the force that holds atoms or ions together
Cation – positive ion
Anion – negative ion
Ionic bond – the force that holds ions together

7. Ionization energy – the amount of energy used to remove an e-
Lower ionization energy = easier to remove an electron

8. Ionic Compounds
Chemical Formula – shows which elements are in a compound and the ratio
Ex. NaCl, MgCl2

9. Crystal lattices – ions are arranged in an orderly, 3-D structure
Crystals – solids whose particles are arranged in a lattice structure

10. Properties of ionic compounds
High melting points
Poor conductors in solid form
Good conductors when melted
Brittle (shatter when struck by a hammer)
When an ionic crystal is struck, ions are moved from their fixed positions. Ions with the same charge repel one another and the crystal shatters.

11. 6.2 Covalent Bonds Form when two or more atoms SHARE e-
Form between two or more nonmetals
Can be polar or nonpolar
Polar – e- are NOT shared equally
Nonpolar – e- ARE shared equally
Form molecules (neutral group of atoms that are joined by covalent bonds)
Atoms may share 1, 2, or 3 prs. of e-

12. Many nonmetals exist as diatomic molecules. Diatomic means “two atoms”

13. Polar Covalent Bonds
One atom has a greater attraction for the e-, making one end of the molecule have a partial neg. charge. The other end has a partial pos. charge.

14. Water is a polar molecule
Water is a polar molecule. The e- spend most of their time with the Oxygen atom, making the O end of the molecule slightly negative and the H end slightly positive.

15. Nonpolar Covalent Bond
Both atoms have an equal attraction for the electrons, so they share them equally.

16. Attraction Between Molecules
Attractions between polar molecules are stronger than between nonpolar molecules.

17. 6.3 Naming Compounds and Writing Formulas
Binary Ionic Compounds
1st word – name of metal
2nd word – name of nonmetal ending in –ide
If the metal is a transition metal, a roman numeral is placed between the metal and nonmetal to indicate which ion.
Ex. Sodium Chloride, Copper (II) Chloride

18. Polyatomic Ions Covalently bonded group of atoms with a charge.
Polyatomic ions act like single atoms when forming chemical bonds.
Polyatomic ions are COVALENTLY bonded to each other, but as a group they bond IONICALLY to another ion.

20. Writing Formulas for Ionic Compounds
Symbol of cation is written first, followed by the symbol of the anion
Use subscripts to show the ratio of ions
Parentheses are used to enclose polyatomic ions

21. Naming Molecular Compounds
MOST metallic element appears first in the name (the one closer to the left on the periodic table)
If both elements are in the same group, the one closer to the bottom is listed first
Use prefixes to indicate the number of atoms
The prefix “mono-” is not used in the first element name.

22. Writing Molecular Formulas
Write the symbols for the elements in the order that they appear in the name
Use the prefixes to determine the number of atoms
Use subscripts to show how many atoms of each element are in a molecule

23. 6.4 The Structure of Metals
Metallic Bonds
Form between two or more metal atoms
Attraction between the metal cation and the shared electrons that surround it
“sea of electrons”

24. Metals are malleable and are good conductors because of metallic bonds.
Alloys
Mixture of two or more elements at least one of which is a metal
Can be designed with specific properties by varying the types and amounts of elements in them.

25. Bronze is a common alloy made usually of copper and tin.
Steel is an alloy of iron that contains small quantities of iron.