Transcript OGT Review Elements

OGT Review
Elements




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


Elements are listed on the Periodic Table of
Elements by atomic number (number of
protons).
Elements are composed of atoms.
Atoms

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.
Atoms Continued

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

Atoms Continued


Protons and neutrons make up the nucleus of an
atom.
Electrons orbit (circle) the nucleus.
 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




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

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.
Chemical Bonds


Atoms are held together in molecules by
chemical bonds.
Chemical bonds store energy.
Ionic Bonds

Ions are formed when an atom gains or loses an
electron to become + or -.
 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


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.
pH





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

Chemical equations must be balanced. This
means that each element appears the same
number of times in both the reactants and
products.

Example:
C + O2  CO2

If there are different amounts of each element
on either side of an equation we must balance it
using coefficients.

Example:
H2 + O2  H2O
This is not balanced. To balance we add
coefficients.
2 H2 + O2  2 H2O
States of Energy

Potential Energy (PE) – Stored energy
Gasoline (chemical)
 Rock on a cliff (position)
 Food (chemical)
 Coal (chemical)


Kinetic Energy (KE) – energy an object has
when it is moving.
Falling rock
 Thrown ball
 Runner
 Waterfall

End of Physical
Science Review
Conduction

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.

Convection

Convection is the transfer of heat by the flow of
a liquid or a gas.

Warm air in a room rises and cool air sinks. This
causes a circular motion called a convection current.
Radiation

Radiation is the transfer of heat through space in
the form of waves.

Heat from the sun travels through the vacuum of
space to reach Earth.
Wave Diagram
What is Force?

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

Gravity

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.

Friction

Friction is a force that resists motion.

It must be overcome to start an object moving
and/or to keep it moving.

Rougher surface+Heavy object = More friction

Smooth surface+Light object = Less friction
Speed and Velocity

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.)


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:
Kilometers/hour (km/hr)
Miles/hour (mi/hr)
Feet/second (ft/s)
Meters/minute (m/min)
Centimeters/second (cm/s)
Acceleration

Acceleration is the rate in change in velocity.
 Can be used to describe increased or
decreased (deceleration) change.
 Acceleration is calculated by subtracting an
object’s starting velocity from it’s final
velocity and dividing by time.
 A = vf – vs / t
Motion of falling objects



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.

In a vacuum (no air) all objects will fall at the same
rate because gravity is the only force acting on them.
Spheres

The Earth consists of 3 spheres:
1. The lithosphere (rock sphere)
2. The hydrosphere (water sphere)
3. The atmosphere (gas sphere)
These are smaller parts of the Biosphere:
The place where all life exists on Earth.
Interaction of Air, Land, and Water

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.

Erosion

Erosion is the process by which rock material at
Earth’s surface is removed and carried away.
 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.
Structure of the Earth

The Earth is composed of 3 layers.
 The crust: outermost layer (5-50 km)
 The mantle: middle layer (~2900 km)
 The core: innermost layer
 Outer core (~2300 km)
 Inner core (~1200 km): Thought to
be solid
Theory of Continental Drift

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.
 The original “super continent” was
called Pangea.
Plate Tectonics

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.
Plate Interactions

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.
Now Do the OGT
Review Questions #2
Earth’s Geologic History


Scientists have pieced together much of Earth’s
history by studying rocks.
There are 3 main rock types:
Sedimentary
 Igneous
 Metamorphic

Sedimentary Rock


Most commonly formed by the deposition of
particles underwater. (dirt being submerged)
About 75% of land surface is covered with
sedimentary rocks.
Igneous Rock


Form from hot molten rock material, either
underground (magma) or on Earth’s surface
(lava)
Volcanoes
Metamorphic Rock


Form from pre-existing rocks that undergo
changes caused by extreme heat and/or
pressure.
Plate motions
Distances in Space
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.
 A light-year is the distance light travels in
a year.

The Big Bang Theory

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 creating the beginning of space and time.
 Matter continued to move away and over time small
amounts combined to form stars and planets.

Evidence




The universe is expanding outward (Red Shift).
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

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.
 The sun contains 99% of all matter in our
solar system.
Types of Symbiosis



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

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.
Variations
Due to variations (differences) among
members of a species, some individuals are
better adapted.
 These organisms survive to reproduce
while others die out.
 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





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






ATP – cellular energy
CO2 taken in and O2 given off – photosynthesis
Flagella – moves a cell
Mitochondria – makes cellular energy
Placebo – fake drug
Ethics