BIOC 1303 Lecture Notes - Lecture 1: Fluoride, Sodium Nitrate, Bayerischer Rundfunk
28 Jun 2018
School
Department
Course
Professor
03-59-191
Week One: January 8 - 12, 2018
Introduction to Organic and Biological Chemistry for Health Sciences
Chapter Five: Compounds and their Bonds
5.1 Octet Rule and Ions
Learning Goal → using the octet rule, write the symbols of the simple ions for the representative elements.
Number of Valence Electrons
- In the electron configuration for phosphorus, there are 5 valence (outer electrons)
electrons in the s and p subshells with the highest number.
Electron Dot Structure
- Is a convenient way to represent the valence
electrons.
Octet Rule
- The stability of the noble gases is associated with 8
valence electrons.
- Ne 2, 8
- Ar 2, 8, 8
- Kr 2, 8, 18, 8
- Atoms can become more stable by acquiring an octet (8 electrons) in the outer shell.
- The process of acquiring an octet involves the loss, gain, or sharing of valence electrons
Metals Form Positive Ions (Cations)
- Metals acquire octets by losing valence electrons.
- The loss of electrons converts an atom to an ion that has the electron configuration of
the nearest noble gas.
- Medals form positive ions because they have fewer electrons than protons.
-This is because ionization energies of the metal groups are low and they readily
lose their valence electrons to nonmetals thus acquiring the configuration of a
noble gas.
- Group 1A metals → ion 1+
- Group 2A metals → ion 2+
- Group 3A metals → ion 3+
find more resources at oneclass.com
find more resources at oneclass.com
Example:
Formation of the Positive ion, Mg2+
- Magnesium forms an ____ by losing its two valence electrons.
- A positive ion forms with a 2+ charge.
Formation of Negative Ions
- When nonmetals gain electrons to achieve an octet arrangement, they form negative
ions.
- The ionic charge of a nonmetal is 3-, 2-, or 1-.
Example:
Formation of the Negative Ion Fluoride F-
- Fluorine forms an octet by adding an electron to its seven valence
electrons.
- A negative ion forms with a -1 charge.
Example of Ionic Charges
find more resources at oneclass.com
find more resources at oneclass.com
03-59-191
Week One: January 8 - 12, 2018
5.1 Learning Check
1. How many valence
electrons does
aluminum have?
a. 2e-
b. 3e-
c. 5e-
2. How does aluminum acquire an octet?
a. Loses 3e-
b. Gains 3e-
c. Gains 5e-
3. What is the ionic charge of an aluminum ion?
a. 3-
b. 5-
c. 3+
4. The symbol for the aluminum ion is?
a. Al3+
b. Al3-
c. Al+
5.2 Ionic Compounds
Learning Goal → Using charge balance, write the correct formula for an ionic compound.
Ionic Compounds
- Consist of positive and negative ions.
- An ionic bond is an attraction between the positive and negative charges.
- An ionic bond is what holds ionic compounds together.
- The formulas of ionic compounds are determined from the charges on the ions.
find more resources at oneclass.com
find more resources at oneclass.com
