Outline
I. Chemical Bonds - Ionic Compounds (CH6) Electron Dot Symbols Lewis Dot Diagrams Predicting Formulas
Bonds
Ionic Bonds - electron transfer process. Typically between a metal and a nonmetals
Covalent Bonds - electrons shared. Typically involving nonmetals.
The Representative Elements
Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings
Rules for Electron Dot Symbols 1. Representative elements in the same
group of the periodic table have the same number of valence electrons
2. The number of valence electrons is represented by “dots” around the symbol of the representative element.
3. The maximum number of valence electrons for any representative element is 8 - Octet Rule.
Learning Check - Aluminum (Al)
1. Number of valence electrons in aluminum is:
A) 1 B) 2 C) 3
2. In Al, the change in electrons to achieve an octet is:
A) loss of 3e- B) gain of 3e- C) a gain of 5e-
3. The Ionic charge of aluminum is:
A) 3- B) 5- C) 3+
4. The symbol for the aluminum ion is:
A) Al3+ B) Al3- C) Al+
1. Number of valence electrons in sulfur is:
A) 4e- B) 6e- C) 8e-
2. Change in electrons for octet requires a:
A) loss of 2e- B) gain of 2e- C) a gain of 4e-
3. Ionic charge of sulfur is:
A) 2+ B) 2- C) 4-
Learning Check
Predicting Ionic Charge
• The number of electrons an atom loses is related to its position on the periodic table.
The Periodic Table and Ions Group IA metals - +1 Group IIA metals - +2 Group IIIA metals - +3 Group VIIA nonmetals - -1 Group VIA nonmetals - -2 Group VA nonmetals - -3
11
Salt is An Ionic Compound
Sodium chloride in “table salt” is an example of an ionic compound. Chemical Formula: NaCl
Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings
Chemical Formulas of Ionic Compounds
For a neutral species, the number of electrons lost and gained must be equal.• The amount of positive charge must equal the
amount of negative charge.Formulas of ionic compounds
Symbol for the positive ion is always written first The charges on the ions are NOT shown in the
formula The subscripts in the formula give the combining
ratio for the ions
Lewis Dot Diagrams
Using the Electron Dot Symbols, write the Lewis Dot Diagram and the Chemical Formula for
Na and Cl
Ionic Formula of NaCl
In an ionic formula,
• The symbol of the metal is written first followed by the symbol of the nonmetal
• The charges of the ions in the compound are not shown
Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings
Lewis Dot Diagrams continued…• Example: What is the Lewis Dot Diagram
and the chemical formula for the ionic compound formed between Mg and Cl?
Charge Balance In MgCl2
In MgCl2• An Mg atom loses
two valence electrons
• Two Cl atoms each gain one electron
Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings
Write the Lewis Dot Diagrams and give the chemical formulas for the ionic compounds formed between the following elements
Na and O
Ca and O
Al and O
Writing Ionic Formulas from ChargesCharge balance is used to write the formula for
sodium nitride, a compound containing Na+ and N3−.
Na+
3 Na+ N3- = Na3N
Na+
3(+1) + 1(3-) = 0
Ionic Chemical Formulas
Give the chemical formula for the ionic compounds made from the following elements:
1. K and F
2. Mg and S
3. Al and S
4. Li and N
Chapter 2 - Measurements
Measurements
Sig Figs” Identifying Rounding Math Operations
Dimensional Analysis Percent Factor Density
Chapter 3 - Matter (and Energy) Chemical vs.Physical
Matter Classified Element Compound Homogeneous Mixture Heterogeneous Mixture
Chapter 4 - Atoms & Elements Periodic Table Symbols for Elements The Atom
History Subatomic Particles
Atomic Symbols Isotopes, Ions
Atomic Mass (amu)
Chapter 5 (Ch4) - Electronic Structure Electromagnetic
Radiation Classical vs Quantum
History Quantum Numbers Electron Configurations Orbital Diagrams Valence Atomic Radii
Practice Problem
The density of diamond is 3.51g/mL. What is the volume (in liters) of the Hope diamond if it has a mass of 44.0 carats?
(1 carat = 0.200g)
Practice Multiple Choice
1). Which species has 16 neutrons?
a. 31P b. 34
S2- c. 36
Cl d. 89Br
- e. none of these
(p = 15) (p = 14) (p=17) (p=35)
2). An isotope of which element is used as the standard for the relative mass scale for atoms?
a. nitrogen b. oxygen c. hydrogen d. gold e. none of these
Practice Multiple Choice
3). Which of the following elements is expected to be chemically similar to calcium (Ca).
a. K b. Sc c. Cl d. Mg e. Al
4). A g-orbital has an “l” quantum number of 4. How many total electrons can this subshell hold?
a. 4 b. 6 c. 18 d. 10 e. 14
l = 4, ml = -4,-3,-2,-1,0,1,2,3,4 (9 values = 9 orbitals x 2 = 18 electrons)