Ions
Ions are atoms, which have gained or lost
electrons, in order to become more stable – it
happens during chemical reactions.
 Ions always have a charge
- Positively charged ions have fewer electrons
than protons – also called cations.
- Most metals form cations – that means they lose
electrons
e.g. Li1+
3
6.94
1+
Li loses an electron
Li1+ Li
Lithium
- Negatively charged ions have more electrons
than protons – also called anions.
- Non-metals that form anions have a name
ending in ‘ide’
e.g. chloride (Cl-), oxide (O2-)
 All non-metals gain electrons (that is, form
anions).
Compounds
Compounds are formed when two or more elements
are chemically combined.
Noble gases with their 8 valence electrons are very
stable elements – they usually don’t form compounds.
Other atoms have different ways of becoming stable –
they either gain or lose electrons when they form
compounds.
- **Metals give up electrons to other atoms,
forming cations.
- **Non-metals accept electrons, forming
anions.
- **Non-metals may share electrons with other
atoms.
e.g. Sulphur dioxide
non-metal
non-metal
There are two basic types of compounds:
1. Molecular
2. Ionic
Molecular Compounds
Atoms which share electrons to become stable form
molecular compounds
These groups of atoms are called molecules
Atoms in molecules are joined by covalent bonds.
All atoms in molecular compounds are non-metals.
Molecular compounds – non-metal and non-metal
joined chemically.
e.g. CO2
Naming and Writing Binary Molecular
Compounds
- When two (binary) non-metallic atoms join by a
covalent bond we have a molecular compound.
e.g. Carbon dioxide
Rules for naming
1. The first element in the compound is the one most
left on the periodic table.
2. The suffix ‘ide’ is attached to the name of the
second element.
3. Prefixes are used to indicate how many atoms of
each type are present in one molecule of the
compound.
Prefixes:
1 = mono
2 = di
3 = tri
4 = tetra
5 = penta
6 = hexa
7 = hepta
8 = octa
9 = nona
10 = deca
MEMORIZE
No “mono” is used with the first element.
e.g. Give the name or formula for each compound:
NO2 – Nitrogen dioxide
N2O – Dinitrogen monoxide
N2O4 – Dinitrogen tetraoxide
Nitrogen monoxide - NO
Dinitrogen pentaoxide – N2O5
Carbon dioxide – CO2
Assignment:
Name or give the formula:
1. Silicon dioxide
2. Sulphur monoxide
3. OF2
4. SiBr4
5. PH3
6. N2O
7. CO
8. NBr3
9. P2I3
10. SO3
11. N2O4
12. Tetraphosphorous hexaoxide
13. Dinitrogen tetraoxide
14. Heptasilicon monobromide
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
Octaboron decaiodide
B2O3
BrF7
N3O6
H2Cl5
Triselenium diastatide
Diarsenic pentaoxide
Sulphur trioxide
C3O2
C2H6
As3Br7
SO2
Selenium monoxide
Diboron trioxide
PF3
P2O5
P4O10
Arsenic trifluoride
BrF7
Hydrogen chloride
N2O
p. 14 #1
Binary Ionic Compounds
Are composed of ions of one metal element and ions of
one non-metal element joined by ionic bonds
Rules for naming
1. The first element in the name of the formula is
the metal
2. The second element, the non-metal, is named as
an ion. The suffix ‘ide’ must be present.
3. No prefixes are used.
e.g.
Fe2O3 – Iron oxide
CuS – Copper sulfide
KCl – Potassium chloride
Writing Formulas for Binary Ionic Compounds
In an ionic compound the total number of positive
charges must equal the total negative charges – the
compound must be electrically neutral.
This fact tells us how many of each atom is necessary to
form a compound.
e.g. sodium chloride
Step 1 – use the table to find the charges on each ion
(element)
Na1+
Cl1-
Step 2 – bring the two ions close together and see what the
net charge is.
Na1+Cl1- the two charges are equal so the formula is
NaCl
Magnesium chloride
Mg2+Cl1Question: how many of each ion is needed so that the
molecule is neutral.
Cl1-
Mg2+
Cl1-
Therefore the formula is
MgCl2
Chromium oxide Cr3+O2-
3+
Cr O
2-
to balance the charges we use a
shortcut method – charges are “traded”
across.
Cr2O3
Calcium oxide
Ca2+O2-
Ca2O2 CaO
Multivalent Cations (metals)
- Some atoms are able to form more then one
cation. Ex. Ni2+ or Ni3+
- In the Stock system, the charge on the cation is
written in brackets, as a Roman numeral after
the name of the metal
Example
Copper (II) oxide
Cu2+O2-
Tin (IV) fluoride
Sn4+F1- SnF4
PbI2
CuO
Lead (II) iodide
Pb2+ I1-
Cr2S3
Cr3+S2-
Chromium (III) sulfide
Is this formula correct LiO
Li1+O2-
No – correct formula is Li2O
Assignment: Name or write the formula for the
following compounds:
1. tin (II) fluride
2. lead (IV) oxide
3. iron (III) oxide
4. iron (III) sulphide
5. potassium chloride
6. sodium oxide
7. lead (II) oxide
8. SbBr5
9. PbBr2
10. NaF
11. sodium bromide
12. iron (III) fluoride
13. sodium chloride
14. lithium nitride
15. silver oxide
16. magnesium bromide
17. barium chloride
18. potassium iodide
19.
20.
21.
zinc sulphide
copper sulphide
p. 11 #1
Review – Naming Molecular and Ionic Compounds
Name ___________________
Binary molecular compound: Use prefixes for naming.
Write the formula of binary molecular compounds
diphosphorus pentaoxide _____________________
trinitrogen heptabromide _____________________
1.
Write the chemical formula of the following:
a)
sulfur hexafluoride
g) dinitrogen hexabromide
b)
carbon dioxide
h) sulfur dioxide
c)
dinitrogen monoxide
i) carbon monoxide
d)
arsenic tribromide
j) tetraphosphorous decaoxide
e)
tetranitrogen hexahydride
k) dinitrogen pentachloride
f) disulfur hexafluoride
l) carbon tetrachloride
2. Write the proper chemical name of the following:
a)
P2Cl5
g) SiS2
b)
NCl3
h) OCl2
c)
CS2
i) NO2(g)
d)
ClBr2
j) P2O5
e)
NO(g)
k) SF6
f)
N2O4
l) PBr5
Ionic compounds
Binary ionic compounds: No prefixes in naming.
3. Name the following binary ionic compound:
Atoms
Involved
Rb F
Cd
Ions Involved
Formula of Compound
Name of
Compound
P
calcium oxide
gallium chloride
Li2Te(s)
InN(s)
4. Write the chemical formula of the following.
a)
lithium hydride
d) magnesium chloride
b)
silver chloride
e) aluminum hydride
c)
sodium oxide
f) barium sulfide
5. Write the proper chemical name of the following:
a) NaCl(s)
d) ScCl3(s)
b) Al2S3(s)
e) AlF3(s)
c) MgI2(s)
f) LiBr(s)
Binary ionic compounds that contain a multi-valent positive ion:
Most transition metals and some representative metals can form more then one kind of ion.
Since these metal elements have more than one valence or positive charge, they can therefore
form more that one binary ionic compound.
6. Write the chemical formula of the following. Include the state.
a)
chromium(II) oxide
b)
tin(II) iodide
c) copper(II) selenide
d) vanadium(V) oxide
e) copper(I) bromide
f) lead(IV) oxide
7. Write the proper chemical name of the following:
a)
MnCl4(s)
d) SnCl4(s)
b)
CuBr2(s)
e) Hg2S(s)
c)
FeO(s)
f) Ni2S3(s)
Today:
p. 8 #1 p.9 #5 p.10 #6 p. 13 #7 p.23 #1
Test Tuesday
Polyatomic Ions
Some ions form groups called complex ions also known as
polyatomic ions on your periodic table. The complex ions form
bonds so strong they act as if they were single ions.
Like single ions, complex ions have a charge.
Consist of two or more different atoms containing an
overall charge. e.g. NO31- nitrate ion
http://images.google.com/imgres?imgurl=http://www.iun.edu/~cpanhd/C101webnotes/chemicalnomenclature/images/polyions.jpg&imgrefurl=http://www.iun.edu/~cpanhd/C101webnotes/chemicalnomenclature/polyatomsalts.html&usg=__-WYRWKLq-pttehH2ZeF0dlC56Q=&h=360&w=429&sz=54&hl=en&start=3&um=1&itbs=1&tbnid=uTIoywSzo0c3DM:&tbnh=106&tbn
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Found in the box at the top of the table.
- All are negatively charged, except ammonium
ion, and most names end in ‘ate’
- All act as non-metals except ammonium ion,
NH41+, which acts as a metal in compounds.
- Naming - same as ionic compounds.
- When writing formulas, brackets must
surround the polyatomic ion (when more than
one is present – i.e. subscript is not 1).
Examples:
1. Potassium sulphate
K2(SO4)
K1+(SO4)2- “trade”
charges
or K2SO4
NH4NO3 Ammonium nitrate
Al(NO3)3 Aluminum nitrate
Sodium sulphate
Na1+
SO42Na1+
Na1+(SO4)2-
Na2SO4
(NH4)1+(PO4)3-
Ammonium phosphate
(NH4)3PO4
Gallium hydrogen carbonate
Ga3+(HCO3)1-
Ga(HCO3)3
Assignment: Write the formula or name the following:
1. magnesium sulphate
2. sodium phosphate
3. ammonium hydroxide
4. copper (II) nitrate
5. Ca(IO3)2
6. FeSO4
7. calcium sulphite
8. nickel (II) sulphate
9. copper (II) nitrate
10. copper (II) hydroxide
11. manganese (II) dichromate
12. sodium perchlorate
13. silver phosphate
14. cobalt (II) permanganate
15. Ca(OH)2
Some ions form groups called complex ions also known as polyatomic ions on your periodic
table. The complex ions form bonds so strong they act as if they were single ions. Like single
ions, complex ions have a charge.
There is only one positive complex ion: NH+, named ammonium. As it has a positive charge,
ammonium will always be the first ion in an ionic compound.
All the other complex ions have negative charges. They will always come after the positive ion in
an ionic compound. The names are given in your periodic table. Note that most of the negative
complex ions contain oxygen as the last element. The names of these always end in either -ate
or -ite.
There is one negative complex ion without the -ate/-ite name ending. It is OH- and is called
hydroxide.
Formulas of compounds containing complex ions are written in and named in the same way as
other ionic compounds.
The Mole
The mole is a number used in chemistry to indicate
the number of atoms or molecules of a substance.
It is equal to 6.02 x 1023.
This number is called Avogadro’s number.
(Similar to dozen) dozen = 12
mole = 6.02 x 1023
Atomic Molar Mass
- It is equal to the mass of 1 mol of all of the
naturally occurring isotopes of the element
- listed for each element on the periodic table
- example 1 mol of iron = 55.85 g/mol
1 mol of zinc = 65.39 g/mol
- some elements exist as molecules such a
nitrogen gas
1mol N2 = 2 x 14.01g/mol = 28.02g/mol
Molar Mass of a Compound (M)
- refers to the mass of 1 mol of any pure
substance.
- to find the molar mass of a compound use the
chemical formula
e.g.
CO2 contains 1 carbon and 2 oxygen
1C = 1 x 12.01g/mol = 12.01
2 O = 2 x 16.00g/mol = 32.00
M = 44.01 g/mol
H2O
Ca(OH)2
2 x 1.01 = 2.02
1 x 16.00 = 16.00
M = 18.02 g/mol
1 x 40.08 = 40.08
2 x 16.00 = 32.00
2 x 1.01 = 2.02
M = 74.10 g/mol
Assignment: Calculate the molar mass of the following
compounds:
1. PbI2
2. NH4OH
4. CaPO4
5. Mn(NO3)5
7. NH3
8. S2N4
10. C6H12O6
11. NH4HS
13. CoCl2
14. Cobalt(III) silicate
15. Potassium phosphate
16. Polonium (II) oxide
17. Mercury (II) sulfide
18. Fe2(OOCCOO)3
19. Zn(OH)2
20.Cu(NO2)2
21.Co2(Cr2O7)3
22. MgHPO4
3. CuSO4
6. Fe(OH)3
9. BaSO4
12. GaI3
Calculating mass of a sample (m)
Molar mass (M) is equal to the mass of one mole of a
compound.
For example the molar mass of water is 18.02 g/mol.
What if we have 2 moles of water?
Then the mass of the water would be 2 x 18.02 = 36.04 g.
We use the following formula:
m = nM
n = # of moles (mol)
m = mass (g)
M = molar mass (g/mol)
How many grams are there in 3.5 moles of francium
nitride?
Step 1 – Write the formula and find the molar mass.
Fr3N
3 Fr – 3 x 223.00 = 669.00
1 N – 1 x 14.01 = 14.01
M = 683.01 g/mol
Step 2 – List what’s given and apply the formula.
n = 3.5 moles
M = 683.01 g/mol
m=?
m = nM
= (3.5)(683.01)
m = 2390.54 g
Mass of a substance to moles
If the mass of the sample is given rearrange the formula
for “n” to find the number of moles.
n=m
M
e.g.
How many moles are there in a 16 g sample of carbon
dioxide.
CO2
1 x 12.01 = 12.01
2 x 16.00 = 32.00
M = 44.01 g/mol
m = 16 g
M = 44.01 g/mol
n=?
n = m/M
= 16/44.01
n = 0.36 moles
Find the number of moles in 0.5 kg of water.
Note: you must change the mass of the sample to grams.
(kg to g x 1000)
m = 500 g
M = 18.02 g/mol
n=?
n = m/M
= 500
18.02
n = 27.75 mol
Moles summary
1. Molar mass (M) – must be calculated using the table.
2. Mass (m) – use the formula
3. Number of moles (n) – use
m = nM
n=m
M
Assignment: Find the number of moles in each sample.
1. 20 g of NH4OH
2. 1.3 kg of CaPO4
3. 670 g of S2N4
4. 0.450 kg of C6H12O6
5. 10 g CoCl2
6. 345 g Potassium phosphate
7. 700 g of Polonium (II) oxide
8. 0.9 kg of Mercury (II) sulfide
9. 200 g of Fe2(OOCCOO)3
10. 1.35 kg of Zn(OH)2
11. 320 g of Cu(NO2)2
12. 1,500 g of Co2(Cr2O7)3
13. 55 g of MgHPO4
14. 480 g of CuSO4
15. 980 g of Mn(NO3)5
16. 0.380 kg of Fe(OH)3
17. 2 kg of Mn(NO3)5
18. 280 g of Fe(OH)3
19. 1.3 kg of Water
20. 50 grams of table salt (Sodium chloride)