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Science Midterm Notes
Noecards for the SAS 8th grade semester exam in Physics/Chemistry.
132
Physics
8th Grade
12/11/2007

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Cards

Term
Science
Definition
a way of learning about the natural world through observations and logical reasoning.
Term
Scientific Enqiry
Definition
a term for the ongoing discovery in science.
Term
Physical Science
Definition
the study of matter, energy, and the changes that matter and energy undergo.
Term
Some of the skills used by scientists include...
Definition
posing questions, making observations and inferences , developing hypothoses, and conducting experiments.
Term
Observation
Definition
a method of scientific inquiry involving all 5 senses .
Term
Inference
Definition
a logical interpretation based on interpretations and prior knowledge.
Term
In science a hypothesis must be testable by...
Definition
an experimant or or observation.
Term
Variable
Definition
factors that can change during an experiment.
Term
Manipulated Variable
Definition
the variable that a scientist changes changes during a controlled expiriment.
Term

Responding Variable

(Dependent Variable)

Definition
the variable that is expected to change because of the manipulated variable.
Term
Controlled Experiment
Definition
an experiment in which all variables but one remain the same.
Term
Scientific Theory
Definition
a well-tested idea that explains and connects a wide range of observations.
Term
Scientific Law
Definition
a statement that descrobes what scientists expect to happen every time under a particular set of circumtances.
Term

Matter

Definition
anything that has mass and takes up space.
Term
Every specific substance has...
Definition
its own combination of properties that can be used to identify the substance.
Term

Chemistry

Definition
the study of the properties of matter and how matter changes.
Term
Elements
Definition
a substance that cannot be broken down into other substances by chemical or physical means.
Term
Elemants are called the building blocks of metter because...
Definition
all matter is composed of elements.
Term
Atoms
Definition

the tiny particles elements are made up of.

Term
Symbol
Definition
a one- or two-letter set of characters used to identify an element.
Term
Compound
Definition
a substance made of two or more elements chemically combined in a specific ratio.
Term
Formula
Definition
a combination of symbols that shows the ratio of elements in a compound.
Term
Mixture
Definition
made from two or more substances- elements, compounds, or both- that are together in the same space but not chemically combined
Term
Physical Change
Definition
a change that alters the form or appearance of a material but not the material into new substances.
Term
Chemical Change
Definition
a change in matter that produces new substances.
Term
Chemical Reaction Definition from Ch. 1
Definition
a change in matter that results in new substance.
Term
Physical changes and chemical changes are...
Definition
the two basic ways in which matter can change.
Term
Weight
Definition
a measure of the force of gravity on an object.
Term
unlike an object's weight, an object's mass...
Definition
will not change when the force of gravity on it changes.
Term

International System of Units

(SI)

Definition
the system of units scientist use to study the properties of matter.
Term

Volume

Definition
the amount of space that matter occupies.
Term
Density
Definition
a measurement of how much mass is contained in a given volume.
Term
Volume Equation
Definition
Volume = Length × Width × Height
Term
Equation for Density
Definition

To calculate the density of an object, divide its mass by volume.

 

Density = mass⁄volume

Term
Chemical Bond
Definition
a force that holds two atoms together.
Term
Molecule
Definition
a combination of two or more atoms that are chemically bonded together.
Term
To obtain an element from its compound it is necessary to...
Definition
cause a chemical reaction to take place.
Term

Solid

Definition
has a definite volume and a definite shape.
Term

A solid has definite shape and volume because...

Definition

the particles are packed so tightly together and stay in fixed positions.

Term
Crystalline Solid
Definition
a solid made up of crystals.
Term
Melting Point
Definition
the distinct temperature at which a crystalline solid melts.
Term
Amorphous Solid
Definition
a solid whose particles are arranged in no regular pattern.
Term
Liquid
Definition
has no definite shape of its own, but has a definite volume. They do not easily compress or expand.
Term

Why does a liquid have no definite shape?

Definition
Because its particles are free to move around.
Term
Viscosity
Definition
a liquids resistance ot flowing.
Term

Gas

Definition

has no definite shape or volume.

Term
What happens when you remove a gas from its container?
Definition
The particles spread out to accomadate the new space.
Term
Temperature
Definition
a measure of the average energy of motion of the particles of a substance.
Term
Pressure
Definition

the outward puch of something divided by the area of the walls of the container its in.

Formula:

Pressure = Force ÷ Area

Term
Boyle's Law
Definition
When the pressure of a gas is increased at a consant temperature, the volume of the gas decreases. When the pressure is decreased, the volume increases.
Term
Relating Temperature and Pressure
Definition
When the temperature of a gas at a constant volume is increased, the pressure of the gas increases. When the temperature is decreased the pressure decreases
Term
Charle's Law
Definition
When the temperature of a gas is increased at constant pressure, When the temperature of a gas is decreased, the volume decreases.
Term

Graphs

Definition
diagrams that tell how two variables, or factors, are related.
Term
Directly Proportional
Definition

when two variables form a straight line passing through the (0,0) point and the relationship is linear and the variables are directly proportional.

Term
Vary Inversely
Definition
when a graph of two measurements forms a curve like:[image]
Term
Thermal Energy
Definition
The energy that the particles of a substance have
Term
Thermal energy always flows from the _____ substance to the ____ substance.
Definition
Thermal energy always flows from the warmer substance to the cooler substance.
Term
A substanxce changes form when...
Definition
its thermal energy increases or decreases by a sufficient amount.
Term
Melting
Definition

the change of form from a liquid to a solid.

Term
Freezing
Definition
the change of state from a liquid to a solid.
Term
Vaporization
Definition
occurs when a liquid gains enough energy to change froma liquid to a gas.
Term
Evaporation
Definition
takes place only on the surface of a liquid. eg a drying puddle.
Term
Boiling
Definition
takes place inside a liquid and on the surface.
Term
Boiling Point
Definition
the specific temperature each liquid boils at
Term
Condensation
Definition
occurs when gas particles lose enough energy to become liquid.
Term
Sublimation
Definition
occurs when the surface particles of a solid gain enough energy to become a gas.
Term
What does an atom consist of?
Definition
[image]
Term
Nucleus
Definition
the tiny, central core of an atom.
Term
Protons
Definition
have a positive electric charge (indicated by a +)
Term
Neutrons
Definition
have a neutral electric charge
Term
Electrons
Definition
negatively (-) charged particles that move rapidly in all directions
Term
Atomic Number
Definition

the number of protons in an element's nucleus

Term

(Atomic) Mass Unit

(amu)

Definition
a measurement of the particles in atoms
Term
Valence Electrons
Definition
the electrons farthest away from the nucleus involved in chemical reactions.
Term
Where does a chemical bond form?
Definition
A chemical bond forms between two atoms when valence electrons move between them. The valence electrons may be moved from one atom to another or shared between them.
Term
Electron Dot Diagram
Definition

made up of an elements symbol surrounded by dots representing valence electrons. EG:

[image]

Term
Periodic Table
Definition
Invented by Isaac Mendeleev, it is an arrangement of elements in order of atomic number, in which elements with similar properties are grouped in columns.
Term
Each square of the periodoc table includes:
Definition

atomic number, chemical symbol, name, and atomic mass.

Term
Group/Family
Definition
the elements in a column
Term
Period
Definition
The elements in a row of the periodic table
Term
How do chemists classify elements?
Definition
Based on physical properties like hardness, shininess, malleability, and ductility.
Term
Malleable
Definition

the ability of a material to be pounded into shapes

Term
Ductility
Definition
the ability of a material to be pulled out or drawn into a wire
Term
Conductor
Definition
a transmitter of heat and electricity
Term
Magnetic
Definition
describes materials that are attracted to magnets and can easily be made into magnets. 
Term
Corrosion
Definition
the process of reaction and wearing away
Term
Alkali Metals
Definition
the matals in Group 1 from lithium to francium. Most reactive metals. Never found uncombined in nature. Used in batteries and medicines .
Term
Alkaline Earth Metals
Definition
More reactive than most. Two most common are magnesium and calcium.  Each atom has 2 valence electrons.
Term
Transition Metals
Definition
Form a bridge between the very reactive metals on the left side to the less reactive metals on the right.
Term
Actinides
Definition
Only two actinides exist on earth in significant amounts. They are very unstable.
Term
Nonmetals
Definition
The elements that lack most elements of metals
Term
Where are the nonmetals located on the periodic table?
Definition
They are located to the right of the zigzag line in the periodic table.
Term
In general the properties of nonmetals......
Definition
Are the opposite of those that characterize metals
Term
Diatomic molecules
Definition
Molecules of two identical atoms
Term
Halogen Family
Definition
Group 17 of the periodic table which contains fluorine,chlorine,bromine,iodine, and astinine
Term
Noble Gases
Definition
Group 18 of the periodic table. They do not gain, lose, lose, or share electrons.
Term
Metalloids
Definition
They are on the border between metals and nonmetals. It has some of the characteristics of both. 
Term

What is the most useful property of a metalloid?

Definition
Their varying ability to conduct electricity
Term
Semiconductor
Definition
Substances that under some conditions can carry electricity but in other circomstances cannot
Term
Plasma
Definition

The state of matter in which atoms are stripped of their electrons and the nuclei are packed close together.

Term
Nuclear Fusion
Definition
Is the process in which atomic nuclei combine to form a larger nucleus, releasing large amounts of energy in the process
Term

Inside stars, nuclear fusion

a. Breaks down a larger nuclei into a smaller nuclei thus making lighter elements

b. combines smaller nuclei to make bigger nuclei, thus creating heavier elements

Definition

B

Inside stars, nuclear fusion combines smaller nuclei to make bigger nuclei, thus creating heavier elements

Term

Supernova

Definition
A tremendous explosion that breaks apart a massive star
Term

T or F ( if F correct the underlined word)

 

The particles that move around in an atom's nucleus are electrons

Definition

The particles that move around in an atom's nucleus are electrons

True

Term

T or F ( if F correct the underlined word)

The alkali metals include iron, copper, silver, and gold.

Definition

The alkali metals include iron, copper, silver, and gold.

F, Transition Metals

Term
Ionic Bond
Definition

The attraction between 2 oppositely charged ions

Term
Convalent Bonds
Definition
The chemical bond formed when 2 atoms share electrons.
Term
Ionic Bonds vs. Convalent Bonds
Definition
Term

Naming Binary Compounds

na+cl

Definition
Sodium chloride
Term
Polar
Definition
A convalent bond in which electrons are shared un- equally
Term
Nonpolar
Definition

The valence electrons are shared equally

Term
Exothermic
Definition
Gives off energy in the form of heat
Term
Endothermic
Definition

absorbs heat

Term

Precipitate

Definition
A solid that forms from a soloution during a chemical reaction
Term
Subscripts
Definition
 Show the number of atoms of an element in a molecule or the ratio of elements in compound
Term
Reactants
Definition

The materials present at the beggining of the chemical reaction

Term
Product
Definition
The materials present at the end of the reaction
Term
Activation Energy
Definition
The minimum amount of energy required to start a chemical reaction
Term
Catalyst
Definition
A material that increases a rate of reaction by decreasing the activation energy
Term
Inhibitor
Definition
A material used to decrease the rate of reaction
Term
Enzyme
Definition
The body's biological catalyst
Term
Suspension
Definition
A mixture in which particles can be seen and easily seperated by settling or filteration
Term

Soloution

Definition
a well-mixed mixture
Term

Solute

Definition
A substance that is present in the smaller amount and is dissolved by the solvent
Term
Solvent
Definition
the part of a solution present in the largest amount
Term
Colloid
Definition
a mixture with small, undissolved particles that do not settle out
Term
Diloute soloution
Definition
 only a little solute is dissolved
Term
Concentrated soloution
Definition
more solute is dissolved in the water
Term
Saturated
Definition
contains as much solute as is possible t the given temperature
Term
Supersaturated
Definition
contains more than solute is possible at the given temperature
Term
unsaturated solution
Definition
does not contain as much solute as is possible t the given temperature
Term

Characteristics of Acids

Definition
tastes sour, reacts with metals & carbonates, & turns red litmus  blue
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