C+O2=CO2
Reactions
example
magnesium ribbon when burnt in oxygen is converted into magnesium oxide
occur with
evolution of gas
example
when zinc reacts with hydrochloric acid, hydrogen gas is evolved with formation of zinc chloride
change in color
example
when iron reacts with oxygen and develops an orange-red color from rusting
change in odor/taste
example
rotting food
production of light
example
when oxygen combines with calcium, adenosine triphosphate (ATP) and the chemical luciferin in the presence of luciferase, a bioluminescent enzyme, light is produced.
change in temperature
example
quick lime with water: CaO + H₂0 = Ca(OH)₂ + Heat
change in state
example
Subtopic
Oxidation-Reduction
effect
corrosion
example
rusting
effect
rancidity
example
when butter is kept in the open atmosphere than its smell and taste change
require activation energy for a reaction to occur
Types of Reactions
Double Displacement (AB+CD=AD+CB)
a precipitate must form in order for a reaction to occur
when two elements in different compounds switch places, forming two new compounds
AgNO3 + NaCl → AgCl + NaNO
Synthesis (A+B=AB)
Decomposition (AB=A+B)
when 1 reactant breaks down (decomposes) to form
multiple products
CaCO3→CaO+CO2
Single Displacement (A+BC=AC+B)
when one element displaces another in a compound
2AgNO3(aq)+Cu(s)→Cu(NO3)2(aq)+2Ag(s)
a balanced chemical equation
the number of atoms for each element in the reaction and the total charge is the same for both the reactants and products.
to accurately reflect the law of conservation, that matter is neither created or destroyed
An ERP chart
reaction will occur when the more active metal displaces the metal that is less active
Combustion (CxHy + O2 = CO2 + H2O + heat energy)
incomplete combustion
when the supply of air or oxygen is poor. H2O is still produced, but carbon monoxide and carbon are produced instead of carbon dioxide.
complete combustion
when a fuel reacts quickly with oxygen (O2) and produces carbon dioxide (CO2) and water (H2O)- when there is a good supply of air.
Precipitation
when an aqueous compound reacts to form an insoluble salt called a precipitate. Whether or not a reaction will form a precipitate is dictated by solubility rules ionic compounds.
Neutralization
Acid + Base = Salt + Water
acids and bases are determined by their pH levels
pH scale
to measure how
acidic
a substance is
basic
ranges from
0.0-6.9
acid
7.0
neutral
can be determined by
indicators
litmus paper
red cabbage water
universal indicator
full color range
< 3
red
strong acid
vinegar (2)
3-6
orange-yellow
weak acid
black coffee (5)
7
green
neutral
pure water (7)
8-11
blue
weak base
baking soda (9)
>11
indigo-violet
strong base
ammonia solution (11)
7.1-14.0
base
very strong acid
very strong base
Acids
Bases
a substance that produces HYDROXIDE IONS (OH⁻) in a solution/take a proton from another compound
physical properties
conduct electricity, slippery touch, water soluble, bitter taste.
chemical properties
corrosive, denature protein and digest fats, react with acids to make neutral solutions.
most bases contain ions/are ionic compounds that contain a metal and a hydroxide polyatomic group
NaOH = sodium hydroxide, Al(OH)3 = aluminum hydroxide
naming rule
"__________hydroxide"
Chemical Equations
include
states
aqueous (aq)
solid (s)
gas (g)
liquid (l)
HCH3CO2(aq)+NaHCO3(s)→CH3CO2Na(aq)+H2O(l)+CO2(g)
Reactants
the substance(s) to the right of the arrow, this is what is produced from the reactants' reaction with each other and is present at the end of the chemical equation.
Fe(s) + S(s) → FeS(s)
Products
the substance(s) to the left of the arrow that is present at the beginning of a chemical reaction
Subscripts
indication to the number of atoms of the preceding element
2NH3
Coefficients
The coefficient tells us how many molecules of a given formula are present and is shown preceding the elements
A word equation should state the reactants (starting materials), products (ending materials), and direction of the reaction in a form that could be used to write a chemical equation.
Iron and sodium nitrate produce iron (II) nitrate and sodium
Fe(s) + NaNO3 (aq) → Fe(NO3)2 (aq) + Na(s)
Periodic Table
Pure Substance
compound
elements
are classified on
periodic table
according to
atomic number
by
Families
Periodic Properties
Submicroscopic
atomic volume
capacity to capture or lose electrons
ions
An ion is a charged atom or molecule. It is charged because the number of electrons do not equal the number of protons in the atom or molecule.
gains an electron
cation
loses an electron
anion
electric conductivity
Macroscopic
melting point
boiling point
density
metallic or non-metallic character
brightness
types of compounds formed
formed by
Atoms
Properties
Models
Lewis Diagram
uses element symbol, shows valence electrons only, valence electrons=electrons in the outermost energy shell.
Bohr Rutherford Diagram
uses element symbol
shows how many protons and neutrons are in the nucleus
shows all electrons in each energy shell (1st energy shell=can hold 2 electrons, 2nd energy shell=can hold 8 electrons, 3rd energy shell=can hold 8 electrons, 4th energy shell=can hold 18 electrons)
electrons space out on the energy shell, and then pair up
Parts
crust
electrons
valence electrons
stable
atoms are at their most stable when their outermost energy level is either empty of electrons or filled with electrons.
negatively charged particles found in the shell of an atom (outside of the nucleus)
nucleus
protons
positively charged particles found in the nucleus of an atom
neutrons
neutral particles found in the nucleus of an atom
Chemical Calculations
Main topic
Solubility
Bronsted-Lowry Theory
when an acid and base are mixed together, the acid will transfer a proton to the base
HCl+NH3=ClNH4
an acid's strength is measured by its ability to donate protons
a base's strength is measured by its ability to receive protons
unstable
instability of an atom's nucleus may result from an excess of either neutrons or protons
different numbers of neutrons in their nuclei
isotope
-Atoms of an element that have the same atomic number but different atomic masses
-Isotopes have the same number of protons, but different numbers of neutrons
-Most elements in nature are a mixture of two or more isotopes, which is why the atomic mass is represented as a weighted average
atoms share electrons to form a stable outer shell of 8
when electrons are
transferred between two or more atoms
ionic
compound
a compound formed between a metal and a non-metal
the
bond
is formed by a transfer of electrons
an attraction that holds two or more
atoms together
the overall charge of an ionic compound is neutral
elements being held together by
a bond in a fixed ratio
formula ---> name
The full name of the metal goes first
The non-metal goes second, and you change the ending to “ide”
Al2O3
aluminum oxide
Name → Formula: CRISS CROSS METHOD
write down both elements and their corresponding charges, then switch their charges
Al3+2-
Al2O3
ionic
multivalent metals
transition metals
capable of having different charges and forming compounds in different proportions are called multivalent metals
rule: roman numerals represent the charge on the multivalent metal ion. Ex Cu⁺² ---> copper (II), can backwards criss cross to find the charge, include roman numerals in word equation and continue to change the ending of the non-metal to "ide"
polyatomic group
when there are more than 2 elements, the compound is polyatomic, have to use the back of the periodic table to identify names, criss cross using brackets
Name the metal normally,
and then use the name from
the polyatomic chart on the
back of the periodic table.
Crisscross the charge of the metal
(found on the periodic table) with
the charge on the polyatomic
(found on the back of the periodic
table). Use brackets when the
number of the polyatomic > 1.
Chemical Formula--> Name
Name-->Chemical Formula
shared between two or more atoms
how to measure?
electronegativity
measure of an atom’s ability to attract a shared
pair of electrons within a molecular bond
trend
electronegativity generally increases as you move from left to right across a period and decreases as you move down a group
how do you find the electronegativity of an element?
the periodic table of elements reveals unique patterns in the properties of chemical elements.
types of trends
difference in electronegativity (∆EN) can be used to determine
bond polarity
non-polar molecule- ∆EN = 0, electrons shared equally
Cl - Cl, N - CL
polar molecule- 0 < ∆EN ≤ 1.7, shared unequally
O - H
molecular polarity
Evaluating all of the bond polarities and overall
shape of the molecule
how do we find the structure?
VSEPR (Valence Shell Electron Pair Repulsion theory)
allows us to predict the geometry (structure) and molecule
polarity of individual molecules based on the number of
electron pairs that surround the central atom
Subtopic
Electron pairs in a valence shell want to stay as FAR
APART from each other as possible, and this affects the shape
of the entire molecule
Molecules have different physical and chemical
properties based on their bond and molecular
polarity.
intermolecular forces
attraction between neighbouring molecules
weaker than molecular bonds
types
London Dispersion
Dipole-Dipole
Hydrogen Bonding
intramolecular forces
molecular bonds within one compound
types
Ionic
Molecular (polar and non-polar)
Partial charges can be assigned to atoms or regions
of the molecule
A molecule can have polar bonds, but be
non-polar overall depending on the shape
If the central atom has any lone pairs (nonbonding), the molecule is POLAR.
Linear and square planar are exceptions.
ionic compound- ∆EN > 1.7, transferred completely
Na - Cl
covalent bonding
hydrogen atoms sharing electrons
molecular compound
compound formed by two non-metals (2 anions)
H2O (water)
write the names of each element in the same order as the chemical formula, change the ending of the second element to "ide.", add prefixes (di, tri, mono, etc...) to match the subscripts for each element, never add MONO to the first name .
Sulfur hexafluoride = SFl₆
The overall charge of a molecular compound
is not always neutral
sodium transfers its electron to chlorine to fill its valence shell
visual representations of bonds
"δ" delta symbol signifies a partial charge
Polar molecules will have a slightly negative pole (with higher
density of electrons) and a slightly positive pole
Higher electronegativity = stronger pull on electrons = slightly
negative end
δ+ = partially positive
δ⁻ = partially negative