Download OGT Review Elements

OGT Review
Elements
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Elements are the basic building blocks of
matter.
There are 115 known elements.
This number changes as new elements are
created in research labs.
90 elements occur in nature and fewer than half
of them are common.
Elements Continued
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Elements are listed on the Periodic Table of
Elements by atomic number (number of
protons).
Elements are composed of atoms.
Atoms
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Atoms are the smallest particle of an element
that has the properties of that element.
John Dalton (1803)- Modern atomic theory.
 All atoms of a particular element are alike, but they
are different from the atoms of any other element.
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Atoms Continued
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Atoms are made up of protons, neutrons and
electrons (subatomic particles).
Protons have a positive charge (+)
 Electrons have a negative charge (-)
 Neutrons have no charge
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Atoms Continued
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Protons and neutrons make up the nucleus of an atom.
Electrons orbit (circle) the nucleus.
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Move around the nucleus in shells or energy levels.
The further away from the nucleus a shell is, the more
electrons it can hold and therefore it has a higher energy
level.
The inner most level can hold 2 electrons, the second can
hold 8, the third up to 18 and so on.
The outer most shell (valence) can hold no more than 8
electrons.
The Periodic Table
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Elements are arranged by atomic number (number of
protons in the nucleus).
Vertical columns are called groups or families.
Horizontal rows are called periods.
Elements located in the same group have similar
electron configurations (same number of valence
electrons). Therefore they will react in similar ways.
Changes in Matter
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Scientists know of millions of different
substances in the world.
How is this possible if there are only 115 known
elements?
 Elements combine to form different substances.
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Chemical Bonds
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Atoms are held together in molecules by
chemical bonds.
Chemical bonds store energy.
Ionic Bonds
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Ions are formed when an atom gains or loses an
electron to become + or -.
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Sodium (Na) can lose its valence electron to form a sodium
ion (Na+).
Chlorine (Cl) can gain an electron to form a chlorine ion (Cl).
An ionic bond is formed when two ions of opposite charges
(metal and nonmetal) are attracted to each other and form a
new substance.
NaCl: Sodium Chloride (table salt).
Covalent Bonds
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Covalent bonds are formed between atoms of
two nonmetals.
Electrons are shared.
Example: Carbon can share electrons with 2 oxygen
atoms (1 with each) to form carbon dioxide (CO2).
 Covalent bonds are stronger than ionic bonds
because of this sharing of electrons.
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pH
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The pH scale refers to strength of an acid or a
base.
The scale ranges from 0-14.
0 is the most acidic. (hydrochloric acid)
14 is the most basic. (sodium hydroxide)
7 is neutral. (water)
Chemical Equations Continued
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Chemical equations must be balanced. This
means that each element appears the same
number of times in both the reactants and
products.
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Example:
C + O2  CO2
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If there are different amounts of each element
on either side of an equation we must balance it
using coefficients.
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Example:
H2 + O2  H2O
This is not balanced. To balance we add coefficients.
2 H2 + O2  2 H2O
States of Energy
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Potential Energy (PE) – Stored energy
Gasoline (chemical)
 Rock on a cliff (position)
 Food (chemical)
 Coal (chemical)
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Kinetic Energy (KE) – energy an object has
when it is moving.
Falling rock
 Thrown ball
 Runner
 Waterfall
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Fission Chain Reaction
Nuclear Fusion
Conduction
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Conduction is the transfer of heat by direct
molecular contact.
Metals are good conductors of heat.
 Example: If you hold a metal rod in fire the heat
will quickly distribute between the molecules in the
rod and it will become hot.
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Convection
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Convection is the transfer of heat by the flow
of a liquid or a gas.
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Warm air in a room rises and cool air sinks. This
causes a circular motion called a convection current.
Radiation
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Radiation is the transfer of heat through space
in the form of waves.
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Heat from the sun travels through the vacuum of
space to reach Earth.
Wave Diagram
What is Force?
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A force is a push or pull that is exerted on an
object.
Force stops motion: gloved hand catching a ball
 Force slows motion: friction slowing a skateboard
 Force changes direction: tennis racket striking a tennis
ball
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Gravity
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Law of Universal Gravitation states that in the
universe every mass attracts every other mass.
Greater mass = greater gravitational force
 An apple falls to Earth because the Earth is much
more massive.
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Friction
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Friction is a force that resists motion.
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It must be overcome to start an object moving
and/or to keep it moving.
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Rougher surface+Heavy object = More friction
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Smooth surface+Light object = Less friction
Speed and Velocity
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Speed and velocity are terms used to describe
the motion of an object.
Speed is the distance traveled over a certain period
of time.
 Velocity is the same but includes a specific direction
(north, east, southwest, etc.)
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The equation used to determine both speed and
velocity is distance divided by time.
S = d/t
V = d/t
 Units for measuring speed/velocity:
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Kilometers/hour (km/hr)
Miles/hour (mi/hr)
Feet/second (ft/s)
Meters/minute (m/min)
Centimeters/second (cm/s)
Acceleration
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Acceleration is the rate in change in velocity.
Can be used to describe increase or decrease
(deceleration).
 Acceleration is calculated by subtracting an object’s
starting velocity from it’s final velocity and dividing
by time.
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A
= vf – v s / t
“Lay a Patch!!!”
Motion of falling objects
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Gravity causes objects released above Earth’s
surface to fall to the ground.
Mass, size and shape of the object determines
how fast it will fall.
Air resistance (air drag) also affects falling
objects.
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In a vacuum (no air) all objects will fall at the same
rate because gravity is the only force acting on them.
Spheres
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The Earth consists of 3 spheres:
1.
2.
3.
The lithosphere (rock sphere)
The hydrosphere (water sphere)
The atmosphere (gas sphere)
All smaller parts of the Biosphere: The place where
all life exists on Earth.
Interaction of Air, Land, and Water
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Weathering is the breaking down of rocks into
smaller pieces.
Physical weathering: water seeps into cracks in rock
and freezes, the water expands, breaking the rock
apart.
 Chemical weathering: oxygen and water chemically
react with iron mineral in rocks, turning to rust,
which crumbles away easily.
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Erosion
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Erosion is the process by which rock material at
Earth’s surface is removed and carried away.
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Erosion requires a moving force (like water).
Example: Streams and rivers turn a muddy brown after a
heavy rain due to the rock material in the water.
 Glaciers and wind can also contribute to erosion.
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Structure of the Earth
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The Earth is composed of 3 layers.
The crust: outermost layer (5-50 km)
 The mantle: middle layer (~2900 km)
 The core: innermost layer
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Outer core (~2300 km)
Inner core (~1200 km): Thought to be solid.
Theory of Continental Drift
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1912: Alfred Wegener proposed the continents
were drifting across Earth’s surface.
Based on how the shapes of the continents fit
together like a puzzle.
 Timetable on pg. 157 shows how the theory
developed from Wegener to the mapping of the
ocean floor in the 1970s
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Plate Tectonics
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Earth’s crust is broken into pieces, or plates, that
slowly move and interact at their boundaries in
various ways.
Caused by heat circulating in the mantle.
 There are 10 major plates: The Pacific, North
American, Nazca, Cocos, South American, African,
Arabian, Eurasian, Indian, and Antarctic.
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Plate Interactions
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As the plates move, some are colliding, some are
spreading apart, and some are sliding past one
another.
Subduction zone: When an oceanic plate collides
with a continental plate it tends to slide down under
it. This forms mountains and volcanoes.
 Fault zones: When one plate slides sideways past
another. This sometimes causes severe earthquakes.
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Earth’s Geologic History
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Scientists have pieced together much of Earth’s
history by studying rocks.
There are 3 main rock types:
Sedimentary
 Igneous
 Metamorphic
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Sedimentary Rock
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Most commonly formed by the deposition of
particles underwater. (dirt being submerged)
About 75% of land surface is covered with
sedimentary rocks.
Igneous Rock
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Form from hot molten rock material, either
underground (magma) or on Earth’s surface
(lava)
Volcanoes
Metamorphic Rock
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Form from pre-existing rocks that undergo
changes caused by extreme heat and/or
pressure.
Plate motions
Distances in Space
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Distances in space are so great they are difficult
to comprehend.
The distance between Earth and the nearest star
(besides the sun) is 41,000,000,000,000 km. (41
trillion)
We use light-years to express distances in space.
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A light-year is the distance light travels in a year.
The Big Bang Theory
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According to this theory, all the matter and
energy that exists in the universe today was once
concentrated in a very small, dense object about
the size of an atom.
For some unknown reason this object suddenly
expanded (in a big bang) creating the beginning of
space and time.
 Matter continued to move away and over time small
amounts combined to form stars and planets.
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Evidence
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The universe is expanding outward.
Galaxies are slowly moving apart.
Galaxies are determined to be about 15 billion
years old.
Large quantities of a hydrogen isotope are
scattered throughout the universe (remnants of
big bang).
The Solar System
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Scientists believe that our solar system formed
about 5 billion years ago.
After the “Big Bang” some gases and dust became
our star (sun).
 The leftover material condensed into planets,
satellites, comets, meteoroids and asteroids.
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The sun contains 99% of all matter in our solar
system.
Types of Symbiosis
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Mutualism: When both organisms benefit.
(butterfly/flower)
Commensalism: When one organism benefits
and the other is not affected. (remora/shark)
Parasitism: When one organism benefits and
the other is harmed. (tapeworm/animal)
Mutualism
Commensalism
Parasitism
Overpopulation
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Overpopulation, competition, and changes in
the environment challenge the survival of all
individuals within a population (same species).
More individuals than the environment can support.
 Competition for resources: food, territory, shelter
and mates.
 Most do not survive to reproduce.
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Variations
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Due to variations (differences) among members
of a species, some individuals are better adapted.
These organisms survive to reproduce while
others die out.
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Natural Selection: “Survival of the Fittest”, “Only
the Strong Survive” etc. – Darwin’s Theory
NATURAL SELECTION
A major misconception about natural selection!
http://evolution.berkeley.edu/evosite/misconceps/IEneeds.shtml
Evolution – the basics
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1. over population
2. constant struggle for resources
3. variation in the species
4. the best adapted to the environment
survive
5. surviving organisms transmit variation to
offspring
Random facts
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ATP – cellular energy
CO2 and O2 – photosynthesis
Flagella – motion
Mitochondria – energy
Placebo – fake drug
Control group? – the group that gets nothing