Download Exam Review – Part 1

Exam Review – Part 1
Chemistry
• Metals (positive ions)
• Non-Metals (negative ions):
Forming Stable Ions
• To become stable some atoms will gain or
lose electrons to form an ion
• For an atom to become stable, it must look
like a noble gas
• That is, they must have a full outer
(valence) shell of electrons (stable octet)
Ionic Compounds
• Ionic compounds are formed when
METAL and NON‐METAL elements
combine to form a neutral compound.
• Metals lose their electrons to the nonmetals, and the resulting ions (positive
and negative) are now attracted to each
other (electrostatic force of
attraction) and form an ionic bond
1) RULES FOR NAMING IONIC
COMPOUNDS
• 1. The METAL ion is written first.
• 2. The NON‐METAL ion is written with the
suffix “‐ide”.
• e.g. NaCl is called sodium chloride
• Al2O3 is called aluminum oxide
• MgCl3 is called _________________
• Do you get it???
• You should memorize the first 20 elements (charges)so
that you don’t have to waste time looking them up.
2) Writing Chemical Formulas
• To obtain the formula of a binary compound with one
metal and one non-metal: E.g. Magnesium Iodide
• a. Write the symbol for each element, putting the metal
atom first.
Mg
I
• b. Write the charge numbers as superscript to the right
of each element.
Mg2+
I• c. Determine how many ions of each type are required
to make the total charge zero.
Mg1(2+)
I2(-1)
• d. Write the chemical formula using the red coefficients
as subscripts (we don’t write the 1)
MgI2
Examples
• E.g. 1 What is the formula of sodium
chloride?
• E.g. 2 What is the formula of magnesium
chloride?
Polyatomic Atoms
• Certain ions are composed of several atoms
that are bonded together through covalent
bonds.
• These atoms carry a net charge and can
form ionic compounds.
• For example, the carbonate ion (CO32‐) is
composed of 1 carbon atom and 3 oxygen
atoms bonded together.
• It carries a net charge of ‐2.
Given on exam…
Table 1: Common Polyatomic Ions
Name of Polyatomic Ion
Charge
ammonium
chlorate
hydrogen carbonate (bicarbonate)
hydroxide
nitrate
nitrite
carbonate
sulfate
sulfite
phosphate
Formula
Ionic
NH4+
ClO3‐
HCO31‐
OH‐
NO3‐
NO2‐
CO32‐
SO42‐
SO32‐
PO43‐
1+
1‐
1‐
1‐
1‐
1‐
2‐
2‐
2‐
3‐
Naming Compounds containing
Polyatomic Ions
• Same rules apply.
1) Name the metal
2) Name the Polyatomic Ion (will have
reference but should try to memorize)
Your Turn
•
•
•
•
•
Try these:
a. K2SO4 ________________________
B. tin (II) nitrate ___________
c. Pb(CO3)2 _______________________
D. beryllium hydroxide ___________
COVALENT BONDING
• Occurs between two non-metals
• Since neither atom will be able to gain
or lose electrons, they will share one or
more pairs electrons between them in
order to follow the octet rule.
Naming Molecular Compounds
• Binary molecular compounds are named
using the prefix system to identify how
many of each element is present in the
compound.
(You must memorize these.)
1 = mono
2 = di
3 = tri
4 = tetra
5 = penta
6 = hexa
7 = hepta
8 = octa
9 = nona
10 = deca
You Try…
•
•
•
•
•
•
a.
b.
E.
F.
G.
H.
P2O3 _________
c.
CCl4 ___________
SO3 _________
d. N2O3________
nitrogen triiodide
_________
silicon tetrachloride _________
carbon monoxide
_________
tetraphosphorous decaoxide
_________
• For a chemical equation to be
completely accurate, it must follow the
law of conservation of mass.
• Based on the Law of Conservation of
Mass …
• the mass of the reactants must equal
the mass of the products.
– This means that we must have the same
number and type of each atom on the
reactant side and product side.
Example
• The combustion of methane (g)
1) Word Equation:
methane + oxygen  carbon dioxide + water
2) Skeleton Equation:
CH4 + O2  CO2 +
H2O
3) There must be the same number of C, H and O
atoms on each side of the equation!
___CH4 + ___O2  ___CO2 + ____H2O
Types of Reactions
• Synthesis reactions involve atoms or molecules joining together to
produce larger compounds.
• General Form:
A
+
B

B
• Eg:
• sodium
+
chlorine
sodium chloride

• Decomposition reactions involve larger compounds breaking down into
elements or smaller molecules.
• General Form:
AB

A
+
B
• Eg:
• carbon monoxide

carbon
+
oxygen gas
SINGLE DISPLACEMENT (REPLACEMENT)
 A chemical reaction in which one element in a compound is displaced (replaced) by another element
Pattern
Fe(s)
+
CuSO4(aq)
→
FeSO4(aq)
+
Cu(s)
3 Cl2(g)
+
2 AlBr3(aq)
→
2 AlCl3(aq)
+
3 Br2(l)
A
+
BC
→
AC
+
B
DOUBLE DISPLACEMENT
 Is the reaction of two ionic compounds in aqueous solution
 The positive ions in their respective compounds switch places to form two new compounds
Pattern
Pb(NO3)2(aq)
+
HCl(aq)
→
PbCl2(s)
BaCl2(aq)
+
Na2SO4(aq)
→
2 NaCl(aq)
AB
+
CD
→
CB
+
HNO3(aq)
BaSO4(s)
+
AD
COMBUSTION REACTIONS
 If oxygen molecules are reactants, some synthesis reactions also may be classified as combustion
reactions
ELEMENTS
 Some elements “burn” in oxygen to form an oxide and energy
Pattern
S(s)
+
O2(g)
→
SO2(g)
+
energy
A
+
O2(g)
→
AO
+
energy*
 *Not always shown in the balanced chemical equation
COMBUSTION
 Hydrocarbons are molecules that contain only carbon and hydrogen
 They are made from fossil fuels (e.g. methane, propane, octane) and contain large amount of
energy
 If enough oxygen is present, they will burn completely and release all of their energy and
produce only two products: carbon dioxide and water (complete combustion)
word equation
propane
+
oxygen
→
carbon dioxide
+
water
balanced chemical
equation
C3H8(g)
+
5 O2(g)
→
3 CO2(g)
+
4 H2O(g)
Acids and Bases
Acid:
 A substance that produces hydrogen ions, H+ (aq), when it dissolves in water.
 Sour-tasting and good conductors of electricity.
 E.g., Hydrochloric acid:
HCl (aq)
H+ (aq)
+
Cl- (aq)
H2SO4 (aq)
Base (Alkali):
 A substance that produces hydroxide ions, OH - (aq), when it dissolves in water.
 Bitter-tasting, slippery-feeling compounds; good conductors of electricity.
 E.g., Sodium hydroxide:
NaOH (aq)
NH4OH (aq)
Na+ (aq)
+
OH- (aq)
Chemical Formulas of Acids and
Bases
Binary Acids
Acid Name
hydrofluoric acid
hydrochloric acid
hydrobromic acid
Oxyacids
Formula
HF (aq)
HCl (aq)
HBr (aq)
Common Bases
Base Name
sodium hydroxide
calcium hydroxide
ammonia
baking soda
Acid Name
nitric acid
carbonic acid
sulphuric acid
phosphoric acid
Formula
NaOH (aq)
Ca(OH)2 (aq)
NH3 (aq)
NaHCO3 (aq)
Formula
HNO3 (aq)
H2CO3 (aq)
H2SO4 (aq)
H3PO4 (aq)
Polyatomic ion
NO3CO32SO42PO43-
pH Scale and Neutralization
Reactions
THE PH SCALE
•
Is used to describe the acidity or basicity of a solution based on the concentration of hydrogen ions in
solution
•
pH refers to the power (strength) of the hydrogen ions
•
An acidic solution has a pH value of less than 7
•
A basic solution has a pH value of more than 7
•
A neutral solution has a pH value of 7

A neutralization reaction is a type of double displacement
reaction:
Acid + Base  Salt + Water

A salt is an ionic compound that is produced by the reaction of a
base and an acid.
ex. NaCl
HCl(aq) + NaOH(aq)  NaCl(aq) + H2O(l)
Practice …
• Correct you Chemistry Test!!!
• Complete Exam Review Questions!!!
• Complete the end of chapter self quizzes for
chapters 5 – 7 (Chem Unit)