1. Ions
Valence Electrons

2. Review…with a partner Ions Cation Anion Ionization energy
Electronegativity

3. Valence Electrons Electrons in the highest occupied energy level
The number of valence electrons determines the chemical properties of an element
To find the number of valence electrons of a representative element, look at its group number
Group 1A has 1 valence electron
Group 2A has 2 valence electrons
Group 8A has 8 valence electrons (He is an exception)

4. Electron Dot structures
Lewis structures
Diagrams that show valence electrons as dots
Don’t double up until you have a dot in each quadrant (He exception)
All of the elements within a group (except He) have the same number of electron dots in their structure

5. Your Turn
Fill in the following table with the correct Lewis structures
Group
Period 1A 2A 3A 4A 5A 6A 7A 8A 1 2 3 4

6. Octet Rule
In forming compounds, atoms want the electron configuration of a noble gas.
Octet=8
Noble gases(except He) ns2np6 and have 8 electrons in their highest occupied energy level
Atoms of metals tend to lose their valence electrons, leaving a complete octet in the next-lowest energy level. Atoms of some nonmetals tend to gain electrons or to share electrons with another nonmetal to achieve a complete octet.

7. Formation of cations
An atom’s loss of valence electrons = cation: positively charged ion.
Sodium atom, Na, forms a sodium cation, Na+
Calcium atom, Ca, forms a calcium cation, Ca2+
Metals
Na 1s22s22p63s1 Lose of valence electron Na+1s22s22p6 Which equals the configuration of Neon
Na  Na+ + e-

8. Formation of anions
Anion is an atom or group of atoms with a negative charge
The gain of electrons
The name of the anion ends in –ide
Chlorine atom forms a chloride ion and oxygen atom forms an oxide ion
Nonmetals
Cl 1s22s22p63s2 3p5 gain of electron Cl- 1s22s22p63s2 3p6 which is equal to the configuration of Ar

9. Anions continued… Cl + e-  Cl-
The ions formed from Group VII A are called halide ions.
7 valence electrons and need to only gain 1 electron to achieve noble gas configuration
Charge of 1-

10. Can u solve it?
How many electrons will each element gain or lose in forming an ion? Ca, F, Al, O
Write the name and symbol on the ion formed when: potassium atom loses 1 electron, zinc atom loses two electron, fluorine atom gains one electron

11. Ionic compounds Composed of cations and anions Electrically neutral
Held together by ionic bond: attraction between positive cation and negative anion
Chemical formula: shows kinds and numbers of atoms (NaCl)
Formula unit: lowest whole-number ratio of ions in an ionic compound (Be2O2 = BeO)

12. Properties of ionic compounds
Crystalline solid at room temperature
High melting points
Conduct an electric current when melted or dissolved in water

13. Ions Monatomic ion: single Polyatomic ions: composed of more than one
Names usually end in –ite or –ate
-ite has 1 less oxygen than -ate
Charges of the cations of transition metals ions must be determined by the # electrons lost.
Form more than one cation with different ionic charges
Table 9.2 on page 255

14. Naming ionic compounds
Cation first, name doesn’t change
Anion second, remove ending and add –ide for monatomic anions
For polyatomic ions use appropriate name from list

15. Metallic bonds Valence electrons of metal atoms are a sea of electrons
Mobile and drift freely from one part of metal to another
Metallic bond: attraction of free-floating valence electrons for the positively charged metal ions.
Good conductors of electric current because electrons can flow freely in them
Malleable/ductile due to mobility of electrons

16. Alloys
Mixtures composed of 2 or more elements, at least one is a metal
Properties are often superior to their component elements