Download O.G.T. SCIENCE TEST: QUICK STUDY GUIDE Chemistry

O.G.T. SCIENCE TEST: QUICK STUDY GUIDE
Chemistry
Matter
Two main families of matter: MIXTURES
and SUBSTANCES
MIXTURES can be separated by physical
means
HOMOGENEOUS- all parts are
equal and looks the same (Kool-Aid)
HETEROGENEOUS- parts are in
different proportions and can be easily
identified (chocolate chip ice cream)
SUBSTANCES cannot be separated by
physical means
ELEMENTS- subs that are made
of one kind of matter
COMPOUNDS- 2 or more
elements bonded together
Atomic Structure
Protons- positive particles in the nucleus
Neutrons- neutral particles in the nucleus
Electrons- negative particles in energy
levels
Nucleus- center of atom; contains the
atoms mass
Valence electrons- electrons on last
energy level of any atom (Magic number is
8)
Energy levels- fixed paths or orbits
surrounding nucleus where electrons are
found
Notable Periodic Families
Group 1- Alkali Metals
Group 2- Alkaline Earth Metals
Groups 3-13ish – Transition metals
Group 7- Halogens
Group 8- Noble Gases
Physical vs. Chemical
Properties/Changes
Physical- reversible; does not change
identity or make up of matter (reversible)
Chemical- creates a new substance;
starting materials are completely different
from ending materials (not reversible)
States of matter
Solid-molecules vibrate but have a
fixed position (definite volume and
shape)
Liquid –molecules can flow easily
past one another (def. volume; take
shape of container)
Gas – molecules move freely (no def.
shape or volume)
Plasma- extremely high energy state
of matter (no def shape or volume)
Periodic Table Basics
Atomic number= number of
protons of an element (whole
number)
Atomic mass= protons +
neutrons (average mass of
isotopes; the one with the
decimal)
Atomic symbol= used to
represent an element
Atomic name= name given to
element
Isotope= same element with
different number of neutrons
Phase changes
SL= melting
LG = evaporation
LS= freezing
GL= condensation
SG= sublimation
GS = deposition
Molecules speed up as they go from a
solid to a liquid to a gas; they slow down
if they move from a gas to a liquid to a
solid
Periodic Table Trends
Group/Family- Vertical columns on the
periodic table
Periods- horizontal rows on the PT
Group number (except for transition
metals) represent numbers of valence
electrons for a certain family
Oxidation number- number of gained or
lost valence electrons for each family
Positive #- metals; they give away
Ve’s to be chemically stable
Negative #- nonmetals; they
receive Ve’s to be chemically stable
Noble gases- chemically stable- have all 8
valence e’s except He (happy with its 2!)
Bonding
Ionic bonding- transferring of valence electrons from a metal
to a non metal (i.e. Na to Cl); oxidation number assigned as
Ve’s are lost or gained
Covalent bonding- complete sharing of valence electrons
between two non metals (i.e. S and O); no oxidation numbers
assigned
Law of Conservation of Energy/Mass- Energy or mass
cannot be created or destroyed it simply changes forms
Mass of reactants= mass of products (sub energy for
mass)
DENSITY
Signs of Chem Reaction
Bubbles (gas formation)
Light/heat
Change in color
Change in odor
Formation of a solid
Acids/Bases
Acids- low pH; sour taste
pH range 6.9-0
Bases- high pH; bitter taste
pH range 7.1-14
pH scale 0-14; 7 is neutral
water is neutral
Lewis Dot Diagram
Valence electron config.
density = mass/volume
Substances that are MORE dense SINK.
Substances that are LESS dense RISE.
Bohr Model
O.G.T. SCIENCE TEST: QUICK STUDY GUIDE
Physics
Forces and Motion (Newton’s Laws)
Force = An action exerted on a body in order to change
that body’s state of rest or motion.
Examples of Force: Push, Pull, Gravity, friction.
Motion = An objects change in position relative to a
reference point.
Speed = An objects distance divided by the time it takes to
move that distance. Speed can be measured as an average
speed or an instantaneous speed.
Velocity = speed with direction.
Acceleration = The change in an objects speed over time.
Newton’s 1st Law: an object in motion stays in motion
and an object at rest stays at rest unless acted on by an
outside force. Also referred to as Inertia.
Newton’s 2nd Law: F = ma (Force = mass X acceleration)
Newton’s 3rd Law: for every action force there is an equal
and opposite reaction force.
Net Force = The sum of all forces acting on an object. If
the net force is zero then forces are balanced.
Friction = A force that opposes motion between two
surfaces that are in contact. Friction will slow an object
down. Types of friction are static, sliding, rolling, and air
resistance.
Gravity: Under ideal conditions, objects fall to the
ground at the same rate; it does not matter if one is heavier
than the other. The constant for the acceleration of gravity
is 9.8m/s/s.
Waves
Wave = A disturbance that carries energy through matter
or space.
Mechanical wave = A wave that requires a medium
through which to travel. (ex. air or water or glass)
Medium = A physical environment in which phenomena
occur.
Electromagnetic wave = A wave that consists of
oscillating (alternating back and forth) electric and
magnetic fields.
Transverse wave = A wave in which particles in the
medium move perpendicular to the motion of the wave.
Ex. Waves on the ocean.
Longitudinal wave = A wave in which particles of the
medium vibrate parallel to the motion of the wave. Ex. the
compression and expansion on an accordion.
Parts of a wave
Crest – The highest point of a wave
Trough – The lowest point of a wave
Wavelength – The distance from any point on a wave to an
identical point on the next wave.
Amplitude – The distance that particles vibrate from the
resting point.
ENERGY
Energy = The capacity to do work.
Work = The force placed on an object to move it a
distance or (f X d). It is expressed in the unit joules.
Power = The amount of time it takes to do work or
(w/t). It is expressed in watts.
potential energy – an object’s stored energy. It is an
energy of position. The higher an object the more
potential energy it would have. The formula for
calculating potential energy is PE = mgh (mass X
gravitational constant X height)
kinetic energy – an object’s energy while in motion (the
faster it moves, the more kinetic energy it has). The
formula for calculating kinetic energy is
KE = ½ mv2 (one half the mass X velocity squared)
Forms of potential and kinetic energy – mechanical,
chemical, heat (thermal), light (radiant), electrical, sound,
nuclear.
The law of conservation of energy states that energy
cannot be created or destroyed but just changes from one
form to another.
Nuclear energy is produced through the fission (splitting)
of atoms or the fusion (combining) of atoms. The sun
produces energy by fusing hydrogen into helium.
Radioactive Decay = The disintegration of an unstable
atomic nucleus.
Half Life = The time required for half of a sample of
radioactive substance to break down by radioactive decay.
Example if Carbon’s half life is 5730 years and I have a
100 g sample then there would be 50 g left after 5730yr.
Wave Interactions – Sound – Light
Reflection – The bouncing back of a ray of light, sound,
or heat when it hits a surface it cannot go through.
Refraction – The bending of a wave as it passes between
two substances in which the speed differs.
Diffraction – A change in the direction of a wave when
hits an obstacle, edge, or opening.
Interference – The combination of two or more waves
that results in a single wave.
Constructive interference – two waves produce a single
wave that is equal to the sum of the two waves.
Destructive interference – two waves produce a single
wave that is equal to the difference between the two
original waves.
Resonance – occurs when two objects vibrate at the same
frequency. It is used to amplify the sound of instruments.
SONAR – SOund Navigation And Ranging . It uses
acoustic signals and echoes to determine the location of
objects.
Electromagnetic spectrum – Consists of waves at all
possible frequencies. Radio wave, microwaves, infared
waves, visible light waves, ultraviolet waves, xrays, and
gamma rays.
RADAR – RAdio Detection And Ranging. Uses reflected
radio waves to determine both the velocity and location of
objects.