1. Chapter 3 Molecules, Compounds, and Chemical Equations

2. Formation of Water from Its Elements

3. How do atom join together to form a compound?
compounds are made of atoms held together by chemical bonds
ionic bonds result when electrons have been transferred between atoms, resulting in oppositely charged ions that attract each other
Metal + Nonmetal
covalent bonds result when two atoms share some of their electrons
Nonmetal + Nonmetal

4. Representing Compounds with Chemical Formula
compounds are generally represented with a chemical formula
all chemical formulas tell what elements are in the compound
use the letter symbol of the element
Empirical Formula describe the kinds of elements found in the compound and the ratio of their atoms
Simplest form of a molecule or compound
they do not describe how many atoms, the order of attachment, or the shape
the formulas for ionic compounds are empirical
Molecular Formula describe the kinds of elements found in the compound and the numbers of their atoms
they do not describe the order of attachment, or the shape

5. Chemical Formulas Hydrogen Peroxide Molecular Formula = H2O2
Empirical Formula = HO
Glucose
Molecular Formula = C6H12O6
Empirical Formula = CH2O

6. Molecular View of Elements and Compounds

7. Ionic Compounds Writing Formulas for Ionic Compounds
metals + nonmetals
no individual molecule units, instead have a 3-dimensional array of cations and anions made of formula units
many contain polyatomic ions
Two or nonmetals are bonded and carried charge
Writing Formulas for Ionic Compounds

8. Some Common Polyatomic Ions
Name
Formula
acetate
C2H3O2–
carbonate
CO32–
hydrogen carbonate
(aka bicarbonate)
HCO3–
hydroxide
OH–
nitrate
NO3–
nitrite
NO2–
chromate
CrO42–
dichromate
Cr2O72–
ammonium
NH4+
Name
Formula
hypochlorite
ClO–
chlorite
ClO2–
chlorate
ClO3–
perchlorate
ClO4–
sulfate
SO42–
sulfite
SO32–
hydrogen sulfate
(aka bisulfate)
HSO4–
hydrogen sulfite
(aka bisulfite)
HSO3–
Tro, Chemistry: A Molecular Approach

9. Examples
Complete the names of the following ions: Ca2+ Al3+ Li+ _________ __________ _________ N3 Se2 F _________ __________ _________ Polyatomic ions NH4+ CO32- NO2- _____________ _______________ ______________ HPO42- CN- ClO4- ______________ _______________ _______________

10. Writing Ionic compound
Identify the cation and anion
Combine the cation and anion together to produce an electrically charged compound.
If the charges on the cation and anion are NOT equal in magnitude, use the charge on the cation as the subscript for the anion. Use the charge on the anion (omitting the negative sign) as the subscript for the cation.
Place parentheses around a polyatomic ion if you need more than one of them in the final formula.
Do not show the charges of the ions when you write the final formula for the compound
Make sure that the subscripts for the cation and anion are the smallest whole number ratio.

11. Examples
What are the formulas and names for compounds made from the following ions?
potassium ion with a nitride ion
calcium ion with a bromide ion
Ammonium ion with a sulfide ion

12. Examples
Write a formula for the combination of the following ions then give a systematic name for each compound
Mg2+ and NO3-
NH4+ and SO42-
Al3+ and PO43-

13. Transitional Metal Cations
Metals with Invariant Charge
metals whose ions can only have one possible charge
Groups 1A+1 & 2A+2, Al+3, Ag+1, Zn+2, Sc+3
cation name = metal name with Roman numeral in parenthesis

14. Examples Write formulas and provide their names
copper(II) ion with a nitride ion
iron(III) ion with a bromide ion
Pb4+ and S2-
Cu2+ and F-

15. Example – Naming Binary Ionic with Invariant Charge Metal CsF
Identify cation and anion
Cs = Cs+ because it is Group 1A
F = F- because it is Group 7A
Name the cation
Cs+ = cesium
Name the anion
F- = fluoride
Write the cation name first, then the anion name
cesium fluoride

16. Example – Naming Ionic Compounds Containing a Polyatomic Ion Na2SO4
Identify the ions
Na = Na+ because in Group 1A
SO4 = SO42- a polyatomic ion
Name the cation
Na+ = sodium, metal with invariant charge
Name the anion
SO42- = sulfate
Write the name of the cation followed by the name of the anion
sodium sulfate

17. Name the following compounds
TiCl4
Al(NO3)3
Au2S3
MnO

18. Practice - What are the formulas for compounds made from the following ions?
copper(II) ion with a nitride ion
iron(III) ion with a bromide ion
aluminum ion with a sulfate ion
chromium(II) with hydrogen carbonate

19. Hydrates Prefix No. of Waters hemi ½ mono 1 di 2 tri 3 tetra 4 penta 5
hexa 6
hepta 7
octa 8
hydrates are ionic compounds containing a specific number of waters for each formula unit
water of hydration often “driven off” by heating
in formula, attached waters follow ∙
CoCl2∙6H2O
in name attached waters indicated by suffix -hydrate after name of ionic compound
CoCl2∙6H2O = cobalt(II) chloride hexahydrate
CaSO4∙½H2O = calcium sulfate hemihydrate
Hydrate
CoCl2∙6H2O
Anhydrous
CoCl2

20. Practice What is the formula of magnesium sulfate heptahydrate?
What is the name of NiCl2•6H2O?

21. Naming Covalent Compounds
Chapter 2: Atoms, Molecules, and Ions
4/26/2017
Naming Covalent Compounds
N2F4
The first element listed is more cationlike and takes the name of the element.
The second element listed is more anionlike and takes the name of the element with an “ide” modification to the ending.
The prefix is added to the front of each to indicate the number of each atom.
dinitrogen tetrafluoride
Copyright © 2008 Pearson Prentice Hall, Inc.

22. Naming Chemical Compounds
Chapter 2: Atoms, Molecules, and Ions
4/26/2017
Naming Chemical Compounds
Binary Molecular Compounds
Whenever the prefix ends in “a” or “o” and the element name begins with a vowel, drop the “a” or “o” in the prefix.
N2O4
dinitrogen tetroxide
Whenever the prefix for the first element is “mono,” drop it.
CO2
carbon dioxide CO
carbon monoxide
Copyright © 2008 Pearson Prentice Hall, Inc.

23. Subscript - Prefixes 1 = mono- not used on first nonmetal 2 = di-
3 = tri-
4 = tetra-
5 = penta-
6 = hexa-
7 = hepta-
8 = octa-
9 = nona-
10 = deca-

24. Name the following
NO2
PCl5
I2F7

25. Example – Binary Molecular dinitrogen pentoxide
Identify the symbols of the elements
nitrogen = N
oxide = oxygen = O
Write the formula using prefix number for subscript
di = 2, penta = 5
N2O5

26. Write formulas for the following
dinitrogen tetroxide
sulfur hexafluoride
diarsenic trisulfide

27. Acids
acids are molecular compounds that form H+ when dissolved in water
to indicate the compound is dissolved in water (aq) is written after the formula
not named as acid if not dissolved in water
sour taste
dissolve many metals
like Zn, Fe, Mg; but not Au, Ag, Pt
formula generally starts with H
e.g., HCl, H2SO4

28. Acids Contain H+1 cation and anion in aqueous solution
Binary acids have H+1 cation and nonmetal anion
Oxyacids have H+1 cation and polyatomic anion

29. Naming Binary Acids write a hydro prefix follow with the nonmetal name
change ending on nonmetal name to –ic
write the word acid at the end of the name
E.g
HCl
HCN

30. Naming Oxyacids
if polyatomic ion name ends in –ate, then change ending to –ic suffix
if polyatomic ion name ends in –ite, then change ending to –ous suffix
write word acid at end of all names
E.g H2SO4 vs. H2SO3

31. Name the following
H2S
HClO3
HNO2

32. Writing Formulas for Acids
when name ends in acid, formulas starts with H
write formulas as if ionic, even though it is molecular
hydro prefix means it is binary acid, no prefix means it is an oxyacid
for oxyacid, if ending is –ic, polyatomic ion ends in –ate; if ending is –ous, polyatomic ion ends in –ous
E.g
Hydrosulfurous acid vs. Carbonic acid

33. Practice - What are the formulas for the following acids?
chlorous acid
phosphoric acid
hydrobromic acid