Download Eighth Grade Review - PAMS-Doyle

Eighth Grade Review
Chemistry
Matter is anything that has mass and
occupies space. All matter is made up of
small particles called atoms.
Matter can exist as a solid,
liquid, gas or plasma
Matter can be classified as elements,
compounds, and mixtures
The atoms
of any
element
are alike
but are
different
from
atoms of
other
elements
Mixtures also consist of two or
more substances, but the substances are
not chemically combined.
. Compounds consist of
two or more elements that
are chemically combined in a fixed ratio.
Compounds
• Compounds can be classified in
several ways, including:
• acids, bases, salts
• inorganic and organic compounds.
(All organic compounds contain
carbon).
Matter can be described by its physical properties that
include, but are not limited to, shape, density solubility, odor,
melting point, boiling point, and color
• Acids make up an important group of
compounds that contain hydrogen
ions. When acids dissolve in water,
hydrogen ions (H+) are released into
the resulting solution. A base is a
substance that releases hydroxide
ions (OH–) into solution.
• pH is a measure of the hydrogen ion
concentration in a solution. The pH
scale ranges from 0–14. Solutions
with a pH lower than 7 are acidic;
solutions with a pH greater than 7
are basic. A pH of 7 is neutral.
Neutralization Equation
To Calculate the density, measure the
mass and volume of substances.
Kinetic Theory of Matter
• The kinetic theory of matter (particle
theory) says that all matter consists of
many, very small particles which are
constantly moving or in a continual state
of motion.
Equal volumes of different
substances usually have different
masses
Matter can be described by its
chemical properties that
include, but are not limited to,
acidity, basicity, combustibility,
and reactivity (including the
ability to rust).
Matter can also be described by its chemical
properties, which include acidity, basicity,
combustibility, and reactivity. A chemical
property indicates whether a substance can
undergo a chemical change.
Atoms of the same element
are alike
The atom is the basic
building block of matter
Atoms and molecules are
perpetually in motion
Protons are positively charged, found in
the nucleus, and = the number of
electrons
• Neutrons are neutral particles and are found
in the nucleus
Electrons are negatively charged
particles found spinning around the
nucleus
Dalton
• Chemical elements are made from atoms
Thomson
• Electrons are around a positively charge
pudding like substance.
Rutherford
• The atom is mostly space, there is a
positively charged nucleus in the center.
Bohr
• The Bohr model is a model used to
describe the atom but it does not depict
the three dimensional aspect of an atom
The electron cloud model
represents our current theory of the
atom which shows that the
electrons are not in a fixed orbit but
an electron cloud
Schrödinger
The periodic table of elements is an
arrangement of elements according
to atomic numbers and properties
Metals, nonmetals, and
Metalloids
Periodic Table Basics:
Essential Question: What are Horizontal Rows called?
Answer: PERIODS
Electron Configuration
• The “Period” number
is equal to the
number of energy
levels in an atom
• Remember:
The number of
electrons are equal to
the number of
protons in a neutral
atom
What are Groups on the
Periodic Table?
Essential Question: Groups are also known as Families of Elements.
They share chemical properties. WHY?
Answer: They have the same number of valence electrons.
Electron Configuration
• For Groups IA – VIII
the group numbers
are equal to the
number of outer shell
electrons or valence
electrons
• Group “IA” has ONE
valence electron
• Group “IIA” has TWO
valence electrons;
etc.
Name that GROUP:
The Alkali Metals
IA = one outer shell electrons
therefore Oxidation state?
+1
Name that GROUP:
The Alkali Earth Metals
IIA = two outer shell electrons
Oxidation state?
+2
Name that GROUP:
The Noble Gases
VIIIA = eight outer shell electrons (except Helium which has 2 but is
FULL)
therefore Oxidation state?
NOT!
Name that GROUP:
The HALOGENS
The Salt Formers
VIIA = SEVEN outer shell electrons
therefore Oxidation state?
-1
Name that GROUP:
The Transition Metals
B series = usually 2 or 3 outer shell
electrons
therefore Oxidation state?
+2 or +3
Chemical Bonding
The information within the boxes on the periodic table can
provide you with the atomic symbol, atomic number, atomic
mass, state of matter at room temperature
Atomic Number:
• The number of
protons in an atom
determines what
element it is.
• Add or subtract even
one proton from an
atom of any element
and you no longer
have the original
element in any form.
Now you have a
different element!
• It is also the number
of electrons in a
neutral atom
• Atomic mass is the
average mass of all
the isotopes of an
element
• Neutrons can be
determined by
subtracting the
atomic mass from the
atomic number.
Atomic Structure: Isotopeshave the number of protons but
different number of neutrons
How many neutrons in the
following isotopes?
Hydrogen – 1
Helium – 4
Lithium – 6
Sodium – 22
The number of electrons in the
outermost energy level determines an
element’s chemical properties and
chemical reactivity
Atoms react to form chemically stable
substances that are held together by
chemical bonds and are represented by
chemical formulas
• C + 02
CO2
Recognizing chemical
equations
• Combustion Reaction
• Organic gas and oxygen
• CH4 +
O2
CO2 +
H2O
• Combustion Reactions always have
carbon dioxide and water as products
To become chemically
stable, atoms lose, gain, or
share electrons
Metal to nonmetal ionic bond
Nonmetal to nonmetal covalent bond
When a metallic element reacts with a nonmetallic element, the metallic element’s atoms
gain or lose electrons forming ionic bonds
When two nonmetals react, atoms
share electrons forming covalent
molecular bonds
When matter undergoes physical change,
the chemical composition of the
substances does not change.
When matter undergoes a chemical
change, different substances are formed
The Law of Conservation of Mass states that in a
chemical reaction, the starting mass of the
reactants equals the final mass of the products
A chemical equation represents the change that
takes place in a chemical reaction
• In a chemical equation, the chemical formulas of the
reactants are written on the left; an arrow indicates a
change to a new substance; and the chemical formulas of
the products are written on the right
Chemical Equations
•
•
The number of atoms on the left side of the equations
must equal the number of atoms on the right side of the
equation.
The equation must be balanced using coefficients - a
number placed in front of the molecule or atom
He
four atoms
HO
2
nine atoms
CO
2
six atoms
A subscript is the number behind the chemical symbol, it never changes.
Balancing
H2 + O2
Left side:
H2O unbalanced
Right Side
H2 + O2
Left side:
H2O balanced
Right side:
Balancing Simple
Equations
•
Aluminum + Oxygen
• Al + O2
• Left side:
•
Al + O2
• 2 Al + O2
• Left side:
•
Al + O2
• Left side:
Aluminum Oxide
Al2O3
Right side:
Al2O3
Al2O3
Right Side:
Al2O3
Right side:
Chemical reactions are classified into two broad
types: ones in which energy is released
(exothermic) and ones in which energy is
absorbed (endothermic)
Nuclear reactions produce a large
amount of energy but there are
potentially negative effects of using
nuclear energy such as disposal of
nuclear waste, fission has more waste
than fusion
• Fission (I break) breaks a
radioactive nuclei into new products
and energy (Nuclear power plant
and atomic bomb)
• Fusion ( You make) takes 2 nuclei
and fuses them into one (power of
the sun and stars)