CHEMISTRY – PSSA REVIEW –
PRESENTATION
CHEMISTRY – PSSA REVIEW
S11.C.1 – Structure, Properties, and Interaction of
Matter and Energy
ATOMS AND SUBATOMIC
PARTICLES
PSSA Eligible Content
S11.C.1.1.1
MATTER
Anything that has mass and takes up space is
known as MATTER.
 There are two kinds of matter:


Pure Substances – Cannot be broken down
Elements
 Examples would include: Fe, Ni, Zn, Hg, Pb, Na, O, He
 Compounds
 Examples would include: Water, Carbon dioxide, Sugar


Mixtures – Blend of two or more simpler substances
Heterogeneous Mixture - each substance retains own
properties
 Examples: Pepperoni Pizza, Chocolate Chip Cookies
 Homogenous Mixture – uniform composition
 Examples: Air, Salt water

PARTS OF THE ATOM

ATOM – the basic building block of matter

Composed of smaller subatomic particles:
Particle
Electrical
Charge
Mass (amu)
Location in
Atom
Proton
Positive (+)
1
Nucleus
Neutron
Neutral (0)
1
Nucleus
Electron
Negative (-)
0
Electron Cloud
PARTS OF THE ATOM
NUCLEUS – Center of atom; contains protons
and neutrons
 ELECTRON CLOUD – Space outside of nucleus;
Contain electrons


Organized into different energy levels at different
distances from the nucleus. Most atoms have more
than one energy level.
STRUCTURE OF THE ATOM
ATOMIC NUMBER – The number of protons in
the nucleus of an atom; No two atoms have the
same atomic number!
 MASS NUMBER – The number of protons plus
the number of neutrons in the nucleus of an atom
 ISOTOPES – Atoms of the same element with
different numbers of neutrons; Same atomic
number but different mass numbers!!

Isotope
Name
Number of
Protons
Number of
Neutrons
Mass
Number
Carbon – 12
6
6
12
Carbon – 14
6
8
14
BASIC LAYOUT (STUDENTS DO NOT HAVE THIS SLIDE)
7 rows = “periods”
18 columns = “groups”
IONS

NEUTRAL ATOM – Number of electrons =
number of protons (positive = negative)


Valence Electrons – electrons located in the
outermost energy level
ION – Atom that has a charge (has either lost or
gained electrons during a reaction)
Cation – Positively charged ion (lost electron(s))
 Anion – Negatively charged ion (gained electron(s))

PARTICLE STRUCTURE AND PHYSICAL
PROPERTIES
S11.C.1.1.2
STATES OF MATTER
SOLID
LIQUID
GAS
Shape
Definite
Indefinite
Indefinite
Volume
Definite
Definite
Indefinite
Motion
Vibrational
Fluid
Random
PROPERTIES OF MATTER

Physical

characteristics of matter that can be observed or
measured without changing the identity of the
substance.


Ex:
Color, texture, phase, malleability, ductility, density,
melting point, boiling point
Chemical

Characteristics of matter that describe how
substances change in chemical composition.

Ex:
flammability, corrosion, decomposition, digestion,
respiration
MASS, VOLUME, DENSITY

Mass



Volume



Amount of matter present in a sample of a substance
Metric base unit = Gram, g
Amount of space occupied by a substance
Metric base unit = Liter, L
Density


Ratio of mass to volume of a substance
D = mass
volume
MOLECULAR SHAPES

Nonpolar


Even distribution of electrical charge
Polar
Uneven distribution of electrical charge
 Dipole (d+, d-)

EFFECTS OF MOLECULAR SHAPE

Nonpolar
Weak attractive forces
 Low melting and boiling points


Polar
Strong attractive forces
 High melting and boiling points

CHEMICAL BONDING AND
CHEMICAL PROPERTIES
S11.C.1.1.3
KEY IDEAS

COMPOUND – Two or more elements combine
chemically

Important characteristics:
Have definite composition
 Can be broken down into simpler substances by chemical
means
 Properties of the compound differ from the properties of the
individual elements making it up!

ELECTRONS AND BONDING

Electrons
Negatively charged particles
 Located in energy levels



Those closest to the nucleus have the smallest amount of energy
ELECTRON CONFIGURATION – Arrangement of
electrons around the nucleus of an atom

Each energy level can hold a specific amount of electrons:
Energy Level
Maximum Number
of Electrons
1
2
2
8
3
8
4
18
ELECTRONS AND BONDING
Valence electrons are lost, gained, or shared when
atoms react with each other to form bonds
 CHEMICAL BONDS – forces that hold atoms
together


Three types:
IONIC BONDS
 COVALENT BONDS
 METALLIC BONDS

IONIC BONDS

IONIC BOND – Formed from transfer of
electrons from a positively charged ion to a
negatively charged ion

OCTET – Atoms seek to have 8 electrons in their
outer most level
COVALENT BONDS

COVALENT BOND – Formed when two atoms
share electrons
OCTET – Seek to have 8 electrons in outer most level
 MOLECULE – Structure formed through covalent
bonding
 LEWIS STRUCTURE – Visually shows covalent
bonding and how electrons are shared

METALLIC BONDING

METALLIC BOND – Formed when two metals
combine

Electron Sea – Group of loosely bound electrons that
are shared by all metal cations (+ charged ions)
THE PERIODIC TABLE
S11.C.1.1.4
BASIC LAYOUT
7 rows = “periods”
18 columns = “groups”
PROPERTIES OF ELEMENTS

Metals
Solid (except Hg), lustrous, malleable, ductile, good
conductors of heat and electricity, tend to lose
electrons in chemical reactions
 On the left of the steps (except Hydrogen)


Nonmetals



Most are gases, dull color or colorless, brittle when in
the solid phase, poor conductors of heat and
electricity, tend to gain electrons in chemical
reactions
On the right of the steps
Metalloids
Blended properties of metals and nonmetals
 On the steps

SPECIAL GROUPS
Group 1 = Alkali Metals
Group 2 = Alkaline Earth Metals
Groups 3-12 = Transition Metals
Group 17 = Halogens
Group 18 = Noble Gases
PROPERTIES OF ELEMENTS (SLIDE 2)

Alkali Metals
React vigorously with nonmetals and water
 Require special storage
 Have 1 valence electron; form +1 ions


Alkaline Earth Metals
Not as reactive as group 1 metals
 Have 2 valence electron; form +2 ions


Transition Metals
Hard solids with high melting points
 Form colorful ions of varying charge


Halogens
Most reactive nonmetals
 7 valence electrons, -1 ions


Noble Gases
Least reactive of all elements
 8 valence electrons = “Octet”

GASES AND GAS LAWS
S11.C.1.1.5
KINETIC MOLECULAR THEORY
GASES:
 No definite shape
 No definite volume
 Molecules are very fart apart
 Elastic collisions
 Weak intermolecular attraction
 Greatly affected by changes in :
 Temperature – average kinetic energy of
molecules; measured in KELVIN
 Pressure – force exerted per unit area;
measured in atm, mmHg, kPa
CHARLES LAW
V1 = V2
T1
T2
 T and V are directly proportional.

BOYLE’S LAW
P1V1 = P2V2
 P and V are inversely proportional

IDEAL GAS LAW
Relates P,V, and T to the number of moles (n) of gas
R = 0.08206 Latm/molK
n = number of moles = mass/molar mass
DENSITY OF GASES
Affected by changes in volume
d = mass
volume
If V increases, density will decrease.
If V decreases, density will increase.
REACTION RATES
S11.C.1.1.6
CHEMICAL REACTIONS

CHEMICAL REACTION – One or more
substance react to produce new, different
substances
 Reactants

 Products
4 types of chemical reactions:
SYNTHESIS
 DECOMPOSITION
 SINGLE REPLACEMENT
 DOUBLE REPLACEMENT

SUMMARY OF REACTIONS
Reaction Type
Definition
General Form
Example
Synthesis
Two or more
substances come
together to form a new
substance
A + B  AB
Iron + Oxygen  Iron
Oxide
Decomposition
One compound breaks
down into simpler
substances
AB  A + B
Water  Hydrogen +
Oxygen
**Single Replacement
One substance
replaces, or switches
place, with another
A + BC  AC + B
Iron + Copper (II)
sulfate  Iron (III)
sulfate + Copper
Double Replacement
Substances change
partners
AB + CD  AD + BC
Iron (II) chloride +
Potassium sulfide 
Potassium chloride +
Iron (II) sulfide
** - Activity Series Required!!
RATE OF REACTION

RATE OF REACTION – How fast a reaction
takes place

Affected by:
Concentration
 Pressure
 Temperature
 Catalyst
 CATALYST – Substance that speeds up a reaction, but it
itself is not consumed

FACTORS AFFECTING RATES OF REACTION
Cause
Effect
Result
Increased
Temperature
Faster speed of
particles
Increased
number of
collisions
Faster rate
Increased
Pressure of a
gas
More particles
come into
contact
Increased
number of
collisions
Faster rate
Increased
Concentration
More particles
available to
come into
contact
Increased
number of
collisions
Faster rate
Presence of
Catalyst
Speeds up
reaction
Makes it easier
for particles to
react
Faster rate
FACTORS AFFECTING RATES OF REACTION

TEMPERATURE – Measure of average kinetic
energy in a substance


Increase temperature = Increased rate of reaction
PRESSURE – Force exerted on a unit area of
surface
Little affect on solids, liquids
 Increase Pressure = Increased rate of reaction


CONCENTRATION – Amount of molecules
present per unit volume


Increased Concentration = Increased rate of reaction
CATALYST – Substance that increases rate
without being permanently changed or used up
FACTORS AFFECTING RATES OF REACTION
EQUILIBRIUM – Stable condition in which
opposing forces cancel out
 REVERSIBLE REACTION – Reactions that can
occur in both the forward and reverse directions


LECHATLIER’S PRINCIPLE – Chemical
reactions will “work” to relieve changes made to
it and get (shift) back into equilibrium
Add more of a substance – shift away from added
 Remove substance – shift towards removed
 Decrease volume – shift toward side with fewer gas

CHEMISTRY – PSSA REVIEW
S11.C.2 – Energy Sources and Transformation of
Energy, or Conversion of Energy
ENERGY CHANGES IN CHEMICAL
REACTIONS
S11.C.2.1.2
CHEMICAL REACTIONS -ENERGY DIAGRAMS
Endothermic Reactions – Require energy
(energy is a reactant)
Products are at a HIGHER energy than the
reactants
Exothermic Reactions – Release energy
(energy is a product)
Products are at a LOWER energy than
the reactants
BOND CHANGES
Breaking bonds is always an ENDOTHERMIC
process
 Making bonds is always an EXOTHERMIC
process

PHYSICAL CHANGES

Change of STATE
Heating Curve
Cooling Curve