Transcript File ghsgt review for the physical science domains2

GHSGT Review for the
Physical Science Domains
Atoms, elements, bonding, compounds,
mixtures, periodic table, Newtons Laws,
Force, Work and Mechanical advantage,
Heat transfer, Radioactivity, Electricity
and Magnetism, Waves, Sound and
Light
What is Matter?
Everything in the universe is either matter
or energy
Matter has mass and takes up space
(volume)
Mass is a measure of inertia
Space L x W x H
Either Pure substance of Elements or
Compounds or mixtures of elements and
compounds
Element- defined by number of protons in
nucleus
Compound- two or more atoms of
elements combined chemically (ionic or
covalent)
Pure Substances
Elements – number of protons in nucleus
of the atom 109 metal or nonmetal
Compounds – chemically combined by
loosing (+) gaining (-) or sharing
electrons
Ions
Ionic bonding – electron transfer from
metal (+) to nonmetal (-) Ca²+ O²CaO
Group1 A.M.(1+) Group2 A.E.M. (2+)
Group3-12 T.M.(1+ to 4+) Boron (3+)
Carbon (4+-) Nitrogen (3-) Oxygen (2Halogens (1-) Noble Gases stable
octect
Formula for Compounds
Sum of the oxidation numbers must
be O
Cross Multiply and use subscripts to
balance
Na 1+ F 1NaF
Ca 2+ F 1CaF2
Na 1+ O 2Na2O
Al 3+ O 2Al2O3
Mixtures
Heterogeneous – can distinguish phases
Homogeneous – solute is dissolved in the solvent
Solid, Liquid or Gas
Colloid – heterogeneous mixture where the
different phases are held in suspension
Tyndall Effect
Physical Change – chemical properties remain the
same change of state
Chemical Change – chemical reaction
rearrangement of atoms new material with new
properties
endothermic or exothermic
Physical Properties include color, density, state
Chemical Properties include reactivity
Atomic Structure
Atom – smallest unit an element with
characteristics of that element
Nucleus and an Electron Cloud mostly empty
space
Nucleus – protons and neutrons mass of the
atom mass number of amu’s
protons are the atomic number and identify the
element
Isotopes – different number of neutrons
Electron Cloud – electrons occur at different
energy levels filling lower levels first 2-8-18-32
divided up into sublevels
Outermost electrons are Valence electrons that
are lost, gained or shared during bonding
Periodic Table is organized by the
electron configuration of elements
Groups or Families have the same
number of valence electrons
Each Period is filling that energy level
ex: 3 valence e- in the third
energy level
Al
3+ oxidation
another ex: 2 valence e- in second
has to be
Be
one more ex: 7 valence e- in the 2
Radioactivity
Radioactivity – spontaneous decay of
unstable nuclei
Strong and Weak
nuclear forces
Unstable because of the proton/neutron
ratio 1:1 small elements 2:3 larger
atom
radioactive isotopes go through series to
become stable releasing alpha, beta and
(particles) and gamma (pure energy)
Alpha decay – 4amu’s 2p 2n He nucleus
produces another element strong nuclear
ex: unstable U-234 undergoes alpha
decay
U-234 yields He²+
and Th-230
Beta decay – high energy electron
emitted from neutron
weak
nuclear force
also changes the element by
converting a neutron into a proton
mass is the same
ex: C-14 to N-14
Gamma does not change the identity,
but does release energy
E=mc²
What is Energy and how is
Energy used?
Energy is the ability to cause a change or
to do work
6 forms – mechanical, electric, thermal,
nuclear, radiant and chemical
Mechanical energy is energy of motion
Motion – change of position relative to a
frame of reference
motion takes place at a certain speed or
velocity
Speed is rate of change in position
rate=time
speed=distance/time
velocity=displacement/time
speed can be constant, changing,
instantaneous or the average is calculated
constant=straight line curve, changing ?
Instantaneous=point, average=total t/dis
Acceleration is rate of change of
displacement
Acc = Δd/Δt a=df-di/tf-ti
m/s/s or
m/s²
Acceleration is the result of an unbalanced
force
Force – push or pull against a mass
Mass – measure of Inertia
Inertia – resistance to acceleration 1st
Law
Newton’s Laws 1st inertia 2nd F=ma
3rd action-reaction
F=ma
kg m/s²
newtons of force
friction – force that opposes motion
static rolling sliding
lubricants push surfaces apart to reduce
friction
Air resistance – air friction of falling
objects
all things fall at the same rate in a
vacuum because of balance of gravity and
inertia
Gravity – force of attraction(?) between all
objects F=ma Wt=ma Wt=mg
g=9.8m/s²
Fg=G m1m2/d²
Work
Work – transfer or conversion of
energy
Energy has six forms and two states
Kinetic energy – energy of motion
KE=1/2mv² kg m²/s² Nm joule
Potential energy – stored energy
PE=mgh kg m/s² m Nm joule
Conservation of energy – energy can
be converted to another form
Power
Power – rate at which work is done
or converted to another form
P=W/t =Fd/t =F/v
kgm²/s²/s
or J/s
Watts hp=746W
Simple Machines multiply force or
distance W=Fd make work easier
Levers – bar, wheel-axel and pulley
Inclined Planes – ramp, wedges and
screws
MA = Le/Lr or Fr/Fe Eff = Wo/Wi
Momentum
Momentum – property or tendency of
a moving object
p=mv kg m/s
Vector – magnitude and direction
Impulse – change in momentum
Requires an unbalanced force
Ft = Δp = mv f – mv i
Heat
Heat – thermal energy that moves
Thermal Energy – causes particle vibration
or sum of internal energies
KE increases and volume will
increase…………thermal expansion
Measured in Joules or cals 1c=4.1J BTU
Temperature measures KE of atoms
K
°C
°F
Tf=(9/5Tc)+32 Tc=5/9(Tf-32)
K=C+273
Heat is transferred by Conduction,
Convection and Radiation
Heat transfer can cause a Phase Change
S-L-G as heat is gained
Heating Curves plot Q vs T where the
Heat of fusion S-L and Heat of
Vaporization L-G need to be added for a
phase change
Heat gained or lost is calculated by
Q=m Δt Cp Cp is specific heat
Cp low in metals high for water
4.184J/g°C wow that is high
measured on a calorimeter
Insulators vs Conductors
Electricity
Electricity – flow of electrons from pos to
neg
Form of energy that can do work
Circuit is the path for electrons open –
no flow closed – current
Circuits have conductors (wires), source
(battery), switch, and loads
Current – number electrons flowing or the
amount of energy I amps
Voltage – electrical potential energy or
energy on each electron push on
electrons V volts
Resistance – opposes flow loads R ohms
Ohm’s Law – V = I R
Resistors control the flow of electrons
fixed or variable dimmer
Electric Charge – Proton=pos
electron=neg opposites attract because
fields ‘fit into’ one another
Static – charge by friction and the
induction method
lightning
Circuits are series and parallel
Series – all loads are on one path
Parallel – alternate path household
Short Circuit – path of least resistance
Electric Power – rate at which electric
energy is converted to other forms
P=W/t watts 1W=1J/s
P=I V watts
kiloWatts
Electric Energy – power x time kWh
Cost = EE x cost/kWh
Direct current (one direction) and
Alternating Current (60 Hz)
Adapters convert AC to DC
Magnetism
Magnetism – field force due to the spin of
electrons in an aligned magnetic domains in
permanent mag
Electrons flowing also creates a mag field around
the wire Right Hand Rule
Lining up domains creates poles
North and South can’t be isolated
Electromagnet – temporary magnet has an iron
core and wire carrying current and converts
electric to mechanical energy
Electric Motors – electromagnet within a
permanent magnet electric to mechanical
Generators – electromagnet in a permanent
magnet mechanical to electrical
Transformers step up or step down voltage to
save power
Waves
Wave – repeating disturbance that transfers
energy in matter or space
Mechanical waves transfer energy through matter
(the medium) and can be longitudinal or
transverse
Electromagnetic waves are disturbances in
electric and magnetic fields transverse
Longitudinal waves are a series of compressions
and rarefactions
ex: sound
or seismic waves
Transverse waves are disturbances that are at
right angles to transfer of energy
Crest Trough Nodes
Wavelength – distance from crest to crest
Amplitude – wave height Energy
Frequency – number of wavelengths or
cycles per second 1/s Hz
Wave Speed=wavelength x frequency
v = λ f m/s
Properties include: reflection, refraction,
diffraction and interference
Reflection – change in direction from a
surface θi = θr
mirrors
Refraction – bending rays due to change
in speed from one medium to another
slowed bends toward normal
Diffraction – waves bend around a barrier
Interference – waves combine to
produce another wave
Constructive – crests and troughs
match and increase amplitude
Destructive – partial or complete
cancellation
Standing – two waves equal in
amplitude and wavelength from
opposite directions appear not to
move
Resonance – natural frequency an
object vibrates when absorbs energy
Sound
Sound is a longitudinal wave caused by a
vibration
Speed of sound depends upon the
temperature and density of the medium
s=λf
increase density increase speed
Increase temperature increase speed
Intensity is the energy amplitude
Loudness is how we perceive intensity
decreases with distance
measured in decibels-15dB whisper -150
Pitch is how we perceive frequency
below 20 Hz infra above 20,000 Hz ultra
Uses of sound include: echolocation,
sonar, ultrasonic imaging and music
Doppler Effect – apparent change in
pitch due to change in relative
position of observer or source
ex: sirens and Corvetts red shifts
Light
Light is a transverse wave or a
disturbance in electric and magnetic fields
electromagnetic
Produced by an oscillating electron
c = 300,000,000 m/s in the vacuum of
space
Duel nature – photons act as particles
(photoelectric effect) and as waves
(reflection,refraction,diffraction)
Range of frequencies of the
electromagnetic spectrum
radio-micro-IR-visible-UV-Xrays-gamma
Colors are λ of light ROYGBIV
Light is produced by incandescent,
fluorescent, neon and by lasers
Polarized – block one plane of light
Lasers are used to produce Holograms
Optical Fibers – total internal reflection
Reflection by mirrors concave and convex
Refraction by lenses convex and concave
Images can br virtual or real, upright or
inverted, magnified or reduced
GHSGT
Wednesday
Study!!!