1. Chapter 6: Chemical Bonds
6.1 Ionic Bonding
Chapter 6: Chemical Bonds

2. Stable Electron Configurations
If highest energy level of an atom is filled with e-, the atom is stable and not likely to react
Chemical properties of an element depend on the number of valence electrons
Electron (Lewis) dot diagram = model in which each dot represents a valence electron

3. Stable Electron Configurations
Highest energy level of a noble gas atom is completely filled
Noble gases have stable electron configurations with 8 valence electrons (two electrons in helium).
Elements tend to react to get electron configurations similar to noble gases

4. Chemical Bonding

5. Chemical bonding
Elements can get a stable electron configuration by transferring of electrons
Ex: A chlorine atom has one electron fewer than an argon atom, adding one electron would give chlorine a stable configuration
Ex: A sodium atom has one more electron than a neon atom, removing one electron would give sodium a stable configuration.

6. Chemical bonding
When sodium reacts with chlorine, an electron is transferred from sodium atom to chlorine atom
Each atom ends up with a more stable electron arrangement than it had before transfer

7. Chemical Bonds
Electron moves from Na to CL

8. Formation of Ions Ionic Bonds = transfer of electrons
When an atom gains or loses an electron, the number of protons does not equal number of electrons
Charge on the atom is not balanced, and atom is not neutral
Ion = Atom that with positive or negative charge
Charge on an ion is represented by a plus or a minus sign
Negative charge = anion
Positive charge = cation

9. Ionic Bonds
Ex: Ion that forms when a chlorine atom gains an electron has 17 protons and 18 electrons
This ion has a charge of 1–.
The symbol for the ion is written Cl1–, or Cl– for short.
Anions like the Cl– ion are named by using part of the element name plus the suffix –ide. Thus, Cl– is called a chloride ion.

10. Ionic Bonds Sodium ion has 11 protons and 10 electrons.
The sodium ion has a charge of 1+.
The symbol for the ion is written Na1+, or Na+ for short.
An ion with a positive charge is a cation.
A cation uses the element name, as in the sodium ion.

11. Formation of Ionic Bonds
A particle with a negative charge will attract a particle with a positive charge
Chemical bond = force that holds atoms or ions together as a unit
Ionic bond =force that holds cations and anions together, forms when electrons are transferred from one atom to another (metal and non-metal)

12. Ionization Energy
Cations (+) form when electrons gain enough energy to escape from atoms
Energy allows electrons to overcome the attraction of the protons in the nucleus
Ionization energy = of energy used to remove an electrons
The lower the ionization energy, the easier it is to remove an electron from an atom

13. Ionization Energy

14. Ionic Compounds
Compounds that contain ionic bonds are ionic compounds, can be represented by chemical formulas
Chemical formula = shows what elements are in a compound, and how many of each
Ex: Chemical formula for sodium chloride, NaCl, indicates one sodium ion for each chloride ion in sodium chloride

15. Binary ionic compounds
Compound made from only two elements is a binary compound
The names have a predictable pattern:
The name of the cation followed by the name of the anion.
Examples: sodium chloride

16. Describing ionic compounds
Formula of an ionic compound describes the ratio of the ions in the compound
2 different compounds of copper and oxygen are below
Has to be at least two names to distinguish red copper oxide from black copper oxide.

17. Polyatomic ions
Polyatomic ion = covalently bonded group of atoms that has a positive or negative charge
Most simple polyatomic ions are anions

18. Ionic Compounds
What is the chemical formula for magnesium chloride?

19. Ionic Compounds
What is the chemical formula for magnesium chloride?
MgCl2

20. Naming ionic compounds
Write the name of the metal first and then the nonmetal.
Add an -ide ending to the non-metal
Use Roman Numerals to indicate charge on a transition metal
Ionic compounds involving polyatomic ions follow the same basic rule:
Write the name of the metal first,
Then the name of the polyatomic anions

21. Section 6.2 Covalent Bonds
Chapter 6: Bonding

22. Covalent Bond Sharing of valence electrons Non-metal and Non-metal
Attraction between shared electrons and the protons in each nucleus hold the atoms together in a covalent bond

23. Covalent Bond

24. Covalent Bond

25. Sharing electrons
When two atoms share one pair of electrons, the bond is called a single bond
Hydrogen atom has one electron, if had two electrons, it would have the same electron configuration as a helium atom
Two hydrogen atoms can achieve a stable electron configuration by sharing their electrons and forming a covalent bond

26. Molecules of elements
Molecule = neutral group of atoms that are joined together by one or more covalent bonds
Many nonmetal elements exist as diatomic molecules
Diatomic means “two atoms”

27. Br-I-N-Cl-H-O-F Brinclhof
Memory Trick:
Br-I-N-Cl-H-O-F
Brinclhof
Sounds like a German name.
There’s also:
I Brought Clothes For Our New Hamster
… either way…

28. Diatomic Molecules
Bromine: Iodine: Nitrogen: Chlorine: Hydrogen: Oxygen: Fluorine:

29. Multiple covalent bonds
2 pairs of electrons shared = double bond
3 pairs of electrons shared = triple bond
Nitrogen has five valence electrons.
When the atoms in a nitrogen molecule (N2) share three pairs of electrons, each atom has eight valence electrons
Each pair of shared electrons is represented by a long dash in the structural formula NN

30. Unequal sharing of electrons
Polar covalent bond = atom with the greater attraction for electrons has a partial negative charge
Other atom has a partial positive charge
Happens because the e- are closer to one atom than the other (one atom attracts e- more)
Type of atoms in a molecule and its shape are factors that determine whether a molecule is polar or nonpolar

31. Unequal sharing of electrons
Except for noble gases, elements on the right of the periodic table tend to have a greater attraction for electrons than elements on the left
Elements at the top of a group tend to have a greater attraction for electrons than elements at the bottom of a group have.

32. Polar covalent bond
Covalent bonds= atoms attract electrons equally and are shared equally

33. Attraction between molecules
Attractions between polar molecules are stronger than attractions between nonpolar molecules
Bonds between polar molecule are stronger than non polar

34. Naming covalent bonds Prefixes tell you how many of each atom you have
Prefix goes in front of the element name
Mono- 1
Di -2
Tri – 3
Tetra -4
Penta – 5
Hexa – 6
Hepta – 7