ATOMS AND
ELEMENTS
Remember that atoms
are the building blocks
of matter, and each
element is made up of a
specific type of atom
CHEMICAL FORMULA
Chemical formulas represent
the composition of
substances using symbols for
elements (e.g., H for
hydrogen, O for oxygen) and
subscripts to indicate the
number of atoms
CHEMICAL FORMULA
In a chemical reaction,
reactants are the substances
that undergo a change, and
products are the new
substances formed.
Tarnish is produced when silver reacts with the sulfur
present in the air producing silver sulfide.
I can identify
what type of
reaction
occurs.
I can write and
balance chemical
equations to
represent
chemical
reactions
accurately.
Chemical Reactions
- a process in which one or more
substances is changed into one or more
substances.
Symbols used in a chemical equation
Symbol/Representation
Meaning
(g)
Gas
(l)
Liquid
(s)
Solid
(aq) aqueous
Substances dissolved in water
Upward arrow (
)
Formation of gases
Formation of precipitates (solids)
Application of heat
substance
Solvent or catalyst* used in the reaction
TYPES OF CHEMICAL
REACTIONS
1. Synthesis Reaction
-
2. Decomposition Reaction
•
3. Single Replacement
a more active substance (i.e., metal, halogen) can
replace the position (i.e., cation, anion) of a less active
substance in a compound.
A + BX
AX + B
Increasing activity
Activity series of metals
A less reactive metal cannot replace a more
reactive metal component of a compound.
Activity series of halogens
F
Cl
Br
I
Increasing reactivity
A more reactive halogen can replace the less
reactive halogen component of an ionic compound.
A less reactive halogen cannot replace a more
reactive halogen.
N.R
4. Double Replacement
- involves the switching of the cations and anions of two
reactants.
AX + BY
AY + BX
5. Neutralization Reaction
•
6. Combustion Reaction
•
EXAMPLE
Acetylene gas will react with molecules of
oxygen gas to produce carbon dioxide gas and
water vapor.
Aqueous aluminum nitrate reacts
with aqueous sodium hydroxide to
form aqueous Aluminum hydroxide and
aqueous Sodium nitrate.
BALANCING A CHEMICAL REACTION
Antoine-Lauren
de
Lavoisier
t
Antoine-Lauren
de
Lavoisier
t
Antoine-Lauren
de
Lavoisier
t Performed
•
•
quantitative analysis
on different reactions.
Deduce the law of
conservation of mass.
LAW OF
States that in every
CONSERVATION
chemical transformation,
the amount of the
reacting substances must
be equal to the amount
of the new substance
produced.
•
•
Element
Number of Atoms(s)
Reactant
Product
Ag
1
2
S
1
1
H
2
2
•
•
Element
Ag
S
H
Number of Atoms(s)
Reactant
Product
2
1
2
2
1
2
I can identify
what type of
reaction
occurs.
I can write and
balance chemical
equations to
represent
chemical
reactions
accurately.
EXAMPLE
• Potassium metal reacts with water to produce aqueous
potassium hydroxide and hydrogen gas
K(s) + H2O(l) → KOH (aq) + H2(g)
2K(s) +2H2O(l) → 2KOH (aq) + H2(g)
Vanadium II oxide with iron III oxide
results in the formation of vanadium V
oxide and iron II oxide.
Liquid carbon disulfide reacts with
oxygen gas to produce carbon
dioxide gas and sulfur dioxide gas.
Solid aluminum carbide reacts with
water to product methane gas and
solid aluminum hydroxide
Mercury II oxide decomposes to
produce mercury and oxygen
SEATWORK
Imagine you are working in a chemical laboratory,
and your supervisor has tasked you with a specific
experiment. You have a piece of aluminum metal
and a solution of copper(II) chloride. Your goal is to
carry out a reaction that will produce aluminum
chloride in solution and solid copper satisfying the
Law of Conservation of Mass.
PROCESS QUESTIONS
1. How do chemical equations help us
understand chemical reactions?
2. What are reactants and products in a
chemical equation?
3. Why is it essential to balance chemical
equations?
I can identify
what type of
reaction
occurs.
I can write and
balance chemical
equations to
represent
chemical
reactions
accurately.