Transcript GHSGT Science Review

GHSGT
Science Review
Day 2-PhySci
Mrs. M. Davis
Mrs. K. Rigdon
GHSGT Science Review—2006
Atom Numbers
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Atomic number = # of protons
Mass number = # of protons and
neutrons
Atomic weight/mass = average of
all the mass numbers for all known
isotopes of an element
Isotope = forms of an element with
different numbers of neutrons
(Carbon-12, Carbon-14)
In atoms, p = e
In ions, p  e Ions = atoms that
have gained/lost electrons
– Cations = positive ions (lost
electrons)
– Anions = negative ions (gained
electrons)
GHSGT Science Review—2006
A little joke….
A hydrogen and an oxygen
atom are walking down the
street, and the hydrogen
is looking very sad.
The oxygen asks the
hydrogen, “What’s wrong?”
The hydrogen says, “I lost
my electron.”
The oxygen says, “Are you
sure?”
The hydrogen says, “Yeah,
I’m positive!”
GHSGT Science Review—2006
Periodic Table
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Organized by atomic number, not atomic mass
http://www.webelements.com/
Atomic
number
Atomic
mass/weight
GHSGT Science Review—2006
Solutions
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Solutions are composed of a solute and a solvent,
mixed together (mixture).
– solute = substance in smaller quantity
– solvent = substance in larger quantity
– solutions in which water is the solvent = aqueous solutions
(water is called the universal solvent)
saturated solution = a solution in which the max
amount of solute has been dissolved
 unsaturated solution = a solution in which an
amount of solute less than the max amount has been
dissolved
 supersaturated solution = a solution in which an
amount of solute more than the max amount has
been dissolved due to an increase in temp.
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GHSGT Science Review—2006
Kinetic Molecular Theory
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KMT = assumes that:
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Three phases of Matter:
– All matter is made of atoms and molecules
that act like tiny particles
– These tiny particles are always in motion. The
higher the temperature, the faster the
particles move
– At the same temperature, more massive
(heavier) particles move slower than less
massive (lighter) particles
GHSGT Science Review—2006
Phase Changes
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Changes of state (solid to liquid, etc.)
GHSGT Science Review—2006
Energy Transfer
Types of energy = electrical,
mechanical, chemical, heat,
light, nuclear, etc.
 One type can be transformed
into another.
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– Example: photosynthesis changes
light E into chemical E
– conduction = the transfer of
energy as heat between particles
as they collide within a substance
or between two objects in contact.
– convection = the transfer of
energy by the movement of fluids
with different temperatures. Note:
a fluid can be a liquid or a gas.
– radiation = the transfer of energy
by electromagnetic waves
GHSGT Science Review—2006
Falling Objects
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All objects fall at the same
rate (on Earth = 9.8 m/s2)
Remember: rate  speed,
rate = change in speed (V)
This picture shows a ball
accelerating at approx. 10
m/s2, which is very close to
the actual value of 9.8 m/s2
You will be given the
formulas that are needed to
solve acceleration and
motion problems.
GHSGT Science Review—2006
Newton’s Laws of Motion
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1st Law = Law of Inertia
• Inertia = the ability of an object to resist change
in motion. Depends upon mass of the object.
 2nd Law = Relationship of Mass & Acceleration
• F = ma Unit of force = Newton (kg•m/s2)
• Remember, work = force•distance
• No movement = no work!
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3rd Law = Law of Balanced/Unbalanced Forces
• Motion is created by unbalanced forces
• Friction = a force that opposes motion. 3 types:
• Sliding = rubbing hands together
• Rolling = walking across a floor (foot rolls)
• Fluid = car traveling down the road (through the air)
GHSGT Science Review—2006
Simple Machines
Reduce the effort force even though more
work is done.
GHSGT Science Review—2006
Pulleys
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Mechanical advantage of a pulley is
determined by counting the
number of supporting ropes.
A block and tackle contains many
pulleys and has a large mechanical
advantage.
MA= 1
MA= 4
GHSGT Science Review—2006
MA=2
Waves
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Longitudinal = energy compress matter as it propagates
(ex: sound waves)
Because they compress matter, sound waves will move faster
through a solid than a liquid/gas.
Transverse = energy radiates as transverse wave; does not
need matter to propagate (ex: light, electro-magnetic
energy)
GHSGT Science Review—2006
Waves, con’t.
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Electromagnetic spectrum: shows diff. types of transverse waves
that carry varying amounts of energy.
Higher frequency = greater energy = short wavelength (X-rays)
Low frequency = less energy = long wavelength (radio, TV waves)
GHSGT Science Review—2006
Reflection
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Reflection = when a wave meets a
boundary and bounces off of it.
GHSGT Science Review—2006
Refraction
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Refraction = occurs when a wave crosses a
boundary from one medium to another. A wave
entering a medium at an angle will change direction.
GHSGT Science Review—2006
Diffraction
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Diffraction = refers to the "bending of waves around an
edge" of an object. Diffraction depends on the size of the
object relative to the wavelength of the wave
GHSGT Science Review—2006
Nuclear Chemistry
Fission = splitting of the atom;
nuclear power, atomic
bomb/nuclear warhead
 Fusion = joining of two atomic
nuclei; sun
 Radioactive decay = unstable
nucleus breaks down (nuclei of
radioisotopes)
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- alpha decay: nucleus releases alpha
particle which is a helium nucleus
- beta decay: nucleus releases a beta
particle which comes from the
breakdown of a neutron
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uncontrolled fission reaction
Half-Life = time it takes for ½ of a
radioactive sample to decay
– 1 half-life = 50% left
– 2 half-lives = 25% left
– 3 half-lives = 12.5% left…and so on…
controlled fission reaction
GHSGT Science Review—2006
Wave Interactions
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Constructive Interference
Wave Interactions
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Destructive Interference
Electricity & Magnetism
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Current = measure of the flow of electric energy;
unit is amps
– AC: alternating current like outlet
– DC: direct current like batteries
electromagnet = a strong magnet created when a
iron core (nail) is inserted into the center of a
current-carrying a solenoid
 the movement of charges causes all magnetism
 electric motor = a device that converts electrical
energy to mechanical energy
 in an electric motor, the current in the coil
produces a magnetic field that interacts with the
magnetic field of the surrounding magnet, causing
the coil to continuously turn
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GHSGT Science Review—2006
Electricity & Magnetism con’t
electromagnetic induction = the production of a
current in a conducting circuit by a change in the
strength, position, or orientation of an external
magnetic field
 when the loop of wire moves into or out of the
magnetic field, a current is induced in the wire
 generator = a device that uses electromagnetic
induction to convert mechanical energy to
electrical energy. Remember, an electric motor is
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a device that converts electrical energy to
mechanical energy, so they’re opposite
GHSGT Science Review—2006
Simple Motor
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A coil of wire turns in a magnetic field. This
causes an electric current to flow in the wire.