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Ions. When an element loses or gains electrons, the net charge is no longer zero.A cation (positive ion) is formed when an element loses electronsAn anion (negative ion) is formed when an element gains electrons. Periodic Trends (Periodicity). Atomic RadiusElements get larger going down
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1. Chapter Four Ionic Compounds
2. Ions When an element loses or gains electrons, the net charge is no longer zero.
A cation (positive ion) is formed when an element loses electrons
An anion (negative ion) is formed when an element gains electrons
3. Periodic Trends (Periodicity) Atomic Radius
Elements get larger going down a column
Elements get smaller going across a row
5. Periodic Trends Ionization Energy (cation formation)
Decreases going down a column
Increases going across a row
Electron Affinity (anion formation)
Decreases going down a column
Increases across a row
9. Ionic Bonds Electrons are transferred from an element with low ionization energy to elements with high electron affinity.
Na transfers an electron to Cl to form NaCl.
This results in a crystal structure with the same number of sodium and chloride ions and thus we say the formula is NaCl.
11. Properties of Ionic Compounds Soluble in water
Conduct electricity
High melting points
Crystalline
12. Ions and the Octet Rule Elements gain or lose electrons in order to attain a full valence shell. (The configuration of the noble gases)
We will assume that the elements all obey an octet rule (8 electrons in the valence shell) except for hydrogen (2 electrons)
14. Ionic Compound Formation Elements will form ions using the octet rule.
Find the Group Number at the top of the column.
If there are less than 4 electrons in outer shell, the atom will lose electrons and the ion will be positive.
If there are more than 4 electrons in outer shell, the atom will gain electrons and the ion will be negative.
15. Group IA Alkali Metals One valence electron
Always +1 ions
Na > Na+ + 1e-
16. Group IIA Alkaline Earth Metals Two valence electrons
Always +2 ions
Mg > Mg 2+ + 2 e-
17. Group IIIA Three valence electrons
Always +3 ions
Al > Al 3+ + 3e-
18. Group VA Five valence electrons
Gains 3 electrons to form 3 ions
N + 3 e- ? N3-
N < N3-
19. Group VIA Six valence electrons
Gains two electrons to form 2 ions
O + 2 e- ? O2-
O < O2-
20. Group VIIA - Halogens Seven valence electrons
Gains one electron to form 1 ions
Cl + 1e- ? Cl-
Cl < Cl-
21. Group VIIIA Noble Gases Eight valence electrons
Cannot gain or lose electrons
Chemically inert
23. Stable Noble Gas Configuation Ions form with the same number of electrons as the noble gases.
Na (11 electrons) > Na+ (10 electrons)
Mg (12 electrons) > Mg 2+ (10 electrons)
O (8 electrons) > O2- (10 electrons)
F (9 electrons) > F- (10 electrons)
24. Isoelectronic Series Ions form with Noble gas configurations
The ions with 10 electrons are:
N3- O2- F- Ne Na+ Mg2+ Al3+
What are the members of the argon isoelectronic series?
25. Lewis Structures We indicate the number of valence electrons using a Lewis Structure
There are four sides around the symbol
Each side can hold two electrons
There are a total of eight around the symbol
26. Polyatomic Ions NH4+ ammonium ion
H3O+ hydronium ion
OH- hydroxide ion
NO3- nitrate ion
CH3COO- acetate ion (C2H3O2-)
HCO3- bicarbonate ion
27. CO32- carbonate ion
SO42- sulfate ion
HPO42- (mono)hydrogen phosphate ion
H2PO4- dihydrogen phosphate ion
PO43- phosphate ion
28. Formulas for Ionic Compounds Formula must be electrically neutral
The number of positive charges must equal the number of negative charges
The subscripts tell how many of each atom are in the formula
29. Sodium and Chlorine
NaCl
Calcium and Chlorine
CaCl2
Aluminum and Chlorine
AlCl3
30. Sodium and Sulfate (SO42-)
Na2SO4
Magnesium and Hydroxide
Mg(OH)2
Barium and Nitrate
Ba(NO3)2
31. Potassium and Phosphate
K3PO4
Magnesium and Phosphate
Mg3(PO4)2
Sodium and Bicarbonate
NaHCO3
32. Ammonium and Acetate
NH4CH3COO
Sodium and Carbonate
Na2CO3
Sodium and Oxygen
Na2O
33. Nomenclature Find position of first element on Periodic Table
Metal with constant charge (Group IA, IIA, Al, Ag, Zn, Cd, and NH4+
Transition Metal with variable charge
Non-Metal
34. Metals with Constant Charge Cation is named as element. Anion is named by changing ending to ide
NaCl sodium chloride
MgCl2 magnesium chloride
Na2O sodium oxide
Mg3N2 magnesium nitride
(NH4)2CO3 ammonium carbonate
35. Transition Metals Roman numerals are used to designate charge on cation
FeCl2 iron(II) chloride (ferrous)
FeCl3 iron(III) chloride (ferric)
Cu2CO3 copper(I) carbonate (cuprous)
CuO copper(II) oxide (cupric)
36. Non-Metals Prefixes are used to tell how many of each atom are present in formula
1-mono 6-hexa
2-di 7-hepta
3-tri 8-octa
4-tetra 9-nona
5-penta 10-deca
37. CO carbon monoxide
CO2 carbon dioxide
CCl4 carbon tetrachloride
XeF6 xenon hexafluoride
38. Acids and Bases Acid A substance that donates protons (H+) in water
Common Acids:
acetic, CH3COOH
carbonic, H2CO3
hydrochloric, HCl
nitric, HNO3
phosphoric, H3PO4
sulfuric, H2SO4
39. Base A substance that provides hydroxide ion (OH-) in solution
Common Bases
Sodium hydroxide, NaOH
Potassium hydroxide, KOH
Barium hydroxide, Ba(OH)2
40. Dissociation in Water Soluble substance dissolve in water by dissociation:
NaCl > Na+ + Cl-
CaCl2 > Ca2+ + 2Cl-
HCl > H+ + Cl-
NaOH > Na+ + OH-