Transcript Ionic Bonds - Building Directory

Start up 11/5/07
For each group indicate the number of valence electrons
group 1
Group 15
group 2
Group 16
group 13
Group 17
group 14
Group 18
List the contributions of the following scientists:
1. Dalton
2. Rutherford
3. Bohr
4. Mendeleev
Start up 11/13/07
Copy the questions and the correct answer.
1.
A student massed a piece of iron on a balance. The most sensitive beam was
marked off in 0.1 g intervals. The student reported the iron’s mass as 12.34 g.
Which of the digits in the measurement is estimated?
A) 1
2.
B) 2
C) 3
D) 4
A student measured the temperature of a boiling solution and found it to be 56.0 °C
at standard pressure. The theoretical temperature of that boiling solution is 55.0 °C.
What is the percent error in the student’s measurement?
A) 18 %
B) 1.8 %
C) 0.18 %
D) 0.018 %
Ionic Bonds
chemical bond – the force that holds two atoms together.
The reason that an atoms form ions is to acquire noble gas
configuration(8 valence electrons).
Octet Rule – atoms tend to gain, lose or share electrons in order
to have a “full” (8 electrons) outer energy level.
When positive ions form, an atom loses one or more electrons.
Na – 1 valence e-
Na+1 – 8 valence e-
Metals tend to lose electrons and become positive ions (cations).
When a negative ion forms an atom gains one or more electrons
F – 7 valence e-
F-1 – 8 valence e-
Nonmetals tend to gain electrons and become negative ions
(anions).
An outer energy level is considered “full” and therefore stable,
if it has 8 electrons, except for the first energy level, only
needs 2 electrons to be “full”
Common Ionic Charges (oxidation numbers)
+1
H +2
+3
-3 -2 -1
B C N O F
Be
Multiple oxidation
states (often +2)
Group 14 elements have a tendency to form covalent bonds,
not ionic, but when they form ionic bonds they usually form
+4 or -4 ions.
Ionic bond – chemical bond resulting from the transfer of electrons
from one atom to another
F – 7 valence e-
Na – 1 valence e-
Na+1
F-1 – 8 valence e-
– 8 valence e-
Na+
ionic bond forms
F-
11/7/07
Copy question and all answers
1. Which of the following pieces of glassware can be used to
measure the volume of a liquid with the greatest accuracy?
A) test tube
C) beaker
B) flask
D) graduated cylinder
2. How many significant figures and in the measurement
20.0m?
A) 1
C) 2
B) 3
D) 0
Na gives up its one valence electron to become Na+; F gains the
electron from Na to become F-. Opposite charges attract each
other.
.
.
:F:
:
Na
Monatomic ions – ions formed from one atom.
ex. Na+, Ca+2, Br-, Al+3
The charges for monatomic ions can be determined from the
periodic table.
Polyatomic ions – ions that consist of more than one atom.
ex. NH4+ - ammonium
OH-
-
hydroxide
CO3-2 - carbonate
Writing Chemical Formulas for Ionic Compounds
Binary ionic compound – contains the ions of only two elements.
calcium fluoride
Ca+2 F-1
Compounds are neutral. How many -1 charges are
required to neutralize one +2 charge?
one calcium ion (+2) is neutralized by two fluorine ions (-1) (-1)
Ca1F2
CaF2
magnesium oxide
Mg+2
O-2
How many oxide ion -2 are needed to neutralize one
magnesium ion +2.
MgO
Criss-Cross Method of Writing Chemical Formulas
Ca+2
F-1
The superscript (charge) of the cation, becomes the subscript
for the anion and the superscript of the anion becomes the
subscript for the cation.
Ca1F2
CaF2
Mg+2
O-2
Mg2O2
Ionic compounds are always reduced to the smallest whole
number ratios.
MgO
calcium nitrate
Ca+2
NO3-1
Ca (NO3)2
parentheses are used if you have more than one polyatomic
ion.
Aluminum sulfate
Al+3
SO4-2
Al2(SO4)3
Write chemical formulas for
1. potassium nitride
2. aluminum sulfide
3. calcium nitrate
4. calcium sulfate
Oxidation numbers for many monatomic ions are determined by
the group of the periodic table.
For some of the transition elements, there is more than one
common oxidation state.
For these metals the oxidation state of the ion is indicated in the
name of the compound.
Copper (I) chloride
Cu+1 Cl-1
CuCl
Copper (II) chloride
Cu+2 Cl-1
CuCl2
Naming Chemical Compounds
Given the chemical formula for a compound to name the
compound, you simply name the positive ion and name the
negative ion.
NaCl
K2SO4
Zn(NO3)2
Sodium chloride
Potassium sulfate
Zinc nitrate
If the cation has more than one oxidation number (ex. Fe+3 and
Fe+2) this must be indicated in the name.
Fe2O3
Iron (III) oxide
FeO
Iron (II) oxide
For cations that form more than one ion, look at your ion chart.
1. Potassium iodide
KI
2. Barium chloride
BaCl2
3. Lithium bromide
LiBr
4. Sodium hypochlorite
NaClO
5. Iron(III) sulfate
Fe2(SO4)3
6. Chromium sulfide
Cr2S3
7. Calcium carbonate
CaCO3
8. Sodium acetate
NaC2H3O2
9. cobalt(II) fluoride
CoF2
10. Sodium phosphide
Na3P
11. Tin (IV) oxide
SnO2
12. gold(III) bromide
AuBr3
13. copper(II) iodide
CuI2
14. Strontium chloride
SrCl2
15. Lithium acetate
LiC2H3O2
16. Magnesium hydroxide
Mg(OH)2
17. Nickel (II) nitrate
Ni(NO3)2
18. Silver oxide
19. Zinc chloride
20. Magnesium phosphate
Ag2O
ZnCl2
Mg3(PO4)2
Properties of Ionic Compounds
1. high melting points and boiling points.
2. Brittle, rigid solids at room temperature
3. Dissolve in water and become good conductors of electricity.
4. With the exception of ammonium, ionic compounds form
between a metal and a nonmetal or a group of nonmetals.
Start up 11/12/07
Write formulas for the following compounds:
1. barium phosphate
2. Chromium (III) sulfate
3. potassium nitride
4. iron (III) chloride