Download General Science Mr. Tiesler Mid Term Exam Study Guide Scientific

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General Science
Mr. Tiesler
Mid Term Exam Study Guide
Scientific Method
The scientific method is a step by step process by which scientists answer questions
The steps of the scientific method are:
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Make an observation
Ask a question
Research the topic
Form a hypothesis
Test the hypothesis
Gather data
Analyze results
Draw conclusions
Communicate results
The Independent Variable is the factor the scientist changes to test a hypothesis.
The Dependent Variable is the factor the scientist observes and measures.
The Control Variable if the factor the scientist does not change (remains constant).
The Experimental Group is the part of the experiment that contains the independent variable.
The Control Group is the part of the experiment that does not contain the independent variable
and is use for comparison.
A Scientific Theory is a summary of a pattern found in nature.
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Explains why thing happen
A Scientific Law is an explanation of a pattern found in nature.
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Explains how things work
A Scientific Model is a representation of an object or system found in nature.
The System Internationale (SI), also known as the metric system, is the system scientists (and the
majority of the world) use measure and record data.
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The meter is the base unit for length
The kilogram is the base unit for mass
The liter is the unit for volume
Energy
Energy is the ability to do work.
Kinetic Energy is the energy associated with the motion of an object.
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1
𝐾𝐸 = 2 𝑚𝑣 2
Gravitational Potential Energy is the energy associated with the position of an object.
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𝑃𝐸 = 𝑚𝑔ℎ, 𝑤ℎ𝑒𝑟𝑒 𝑔 = 9.8 𝑚⁄𝑠 2
Elastic Potential Energy is the energy associated with an object that is stretched or compressed.
Thermal Energy is the total kinetic and potential energy associated with the atoms and
molecules of an object.
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Energy associated with the heat of an object
Chemical Energy is the energy stored in the chemical bonds between atoms.
Electrical Energy is the energy associated with electrical charges.
Electromagnetic Energy is energy that travels in waves.
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Includes energy from visible light, gamma rays, x-rays, ultraviolet rays, infrared rays,
microwaves and radio waves
Nuclear Energy is the energy stored in the nucleus of an atom.
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Fission is the energy released when the nucleus of an atom is split apart
Fusion is the energy released when two small nuclei are fused together to form one large
nucleus
The Law of Conservation of Energy states that energy cannot be created or destroyed but it can
be converted from one form to another.
Heat is the transfer of thermal energy from one object to another due to a temperature difference.
 Flows spontaneously from hot objects to cold objects
Temperature is the measure of how hot or cold an object is based on a reference point.
Temperature is measured in degrees Fahrenheit, degrees Celsius, of Kelvin
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The freezing point of water on the Fahrenheit scale is 32o
The boiling point of water on the Fahrenheit scale is 212o
The freezing point of water on the Celsius scale is 0o
The boiling point of water on the Celsius scale is 100o
Absolute Zero on the Kelvin scale is equivalent to -273oC
Specific Heat is the amount of energy needed to raise the temperature of one gram of a
substance by one degree Celsius.
Conduction is the transfer of thermal energy without the transfer of matter.
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Can occur between particles of the same material
Can occur between particles of different materials
Thermal Conductors are materials that easily conduct thermal energy
o Metals
Thermal Insulators are materials that do not conduct thermal energy
o Wood, Air, Glass
Convection is the transfer of thermal energy when particles of a fluid move from one location to
another.
Radiation is the transfer of thermal energy by waves moving through space.
Atomic Theory
The Greek philosopher Democritus was the first to theorize that all matter was made of tiny
particles that could not be divided.
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He called these tiny particles “atoms”
o Greek for indivisible
Aristotle stated that all matter was made of four elements
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Earth
Air
Fire
Water
Dalton’s Atomic Theory:
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All elements are composed of atoms
All elements of the same element have the same mass
Atoms of different elements have different masses
Compounds contain more than one element
In compounds, elements always combine in the same ratios
J.J. Thompson’s Atomic Theory:
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Used electric currents to study atoms
Discovered the electron
Atom was a solid, positively charged sphere with small, negatively charged electrons
embedded within it. (Plum Pudding model)
Ernest Rutherford’s Atomic Theory:
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Protons are positively charged particles found in the nucleus
Electrons are negatively charged particles orbiting the nucleus
Bohr’s Atomic Model:
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Electrons move in fixed orbits around nucleus
Different orbits represent different energy levels
Electrons can move between energy levels as they gain or lose energy
The closer to the nucleus, the lower the energy of an electron
The further away from the nucleus, the higher the energy of the electron
Electron Cloud Model:
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Electrons do not travel around the nucleus in fixed orbits like planets orbiting the Sun
It is impossible to pinpoint the exact location of an electron at any given moment
o Propellers on a plane
Electron Cloud – A visual model of the most likely locations for an electron
Neutrons, particles with no charge located in the nucleus, discovered by James Chadwick in
1932.
Protons and Neutrons have about the same mass, electrons are 2,000 times smaller than protons
and neutrons.
The Atomic Number equals the number of protons in the nucleus
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Every element has a different number of protons
The Atomic Mass is the sum of the protons and neutrons in the nucleus.
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# of neutrons = atomic mass – atomic number
Atomic mass is a weighted average of the different isotopes of an element
Isotopes are atoms of the same element that have different numbers of neutrons.
Periodic Table
Dmitri Mendeleev created first useful table of known elements.
 Based table on solitaire game
 Arranged elements by increasing atomic mass
 Divided elements into rows so that elements with similar properties were in the same
column
 Left blank spaces for undiscovered elements
Modern periodic table arranged by increasing atomic number
 Mendeleev didn’t know about protons
o Protons hadn’t been discovered yet
Periods are the horizontal rows on the periodic table.
 Each period is associated with the highest energy level of electrons
 There are seven periods on the periodic table
 Electrons in the outermost energy level (shell) are Valance Electrons
Groups are the vertical columns on the periodic table.
 Elements within the same group have similar properties
 Elements in the same group have the same number of valance electrons
The three classes of elements are Metals, Nonmetals, and Metalloids.
 The majority of elements are metals
 Bromine (nonmetal) and Mercury (metal) are the only elements that are liquid at room
temperature
Alkali Metals are Group One metals
 Lithium, Sodium, Potassium, Rubidium, Cesium, Francium
 Highly reactive
 Only found in compounds in nature
Alkali Earth Metals are Group Two elements
Halogens are Group Seven elements.
 Highly reactive
Noble Gases are Group Eight elements.
 Nonreactive
 Stable electron configurations
 Elements will gain, lose or share electrons to achieve electron configuration of nearest
noble gas
Ionic Bond – Chemical bond where electrons are transferred from one atom to another.
Covalent Bond – Chemical bond where two atoms share a pair of electrons.
 Polar Covalent Bond – Electrons are not shared equally between atoms
Carbon atoms have four valance electrons.
 Can form single, double, or triple covalent bonds
 Is found in millions of compounds
 Is the basis of all life as we know it
Organic Compounds are compounds that contain hydrogen and carbon.