9Th Grade Science Terms

Front 1

Science

Back 1

a system of knowledge and the methods you use to find that knowledge

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Technology

Back 2

the use of knowledge to solve practical problems

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Chemistry

Back 3

the study of the composition, structure, properties and reactions of matter

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Physics

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the study of matter and energy and the Interactions between the two through forces and motion

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Geology

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the study of the origin, history, and structure of earth

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Astronomy

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the study of the universe beyond Earth, including the sun, moon, planets, and stars.

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Biology

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life science

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Scientific Method

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organized plan for gathering, organizing, and communicating information

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Observations

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information that you obtain through your senses

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Hypothesis

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is a proposed answer to a question

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Manipulated Variable

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the variable that causes a change in another

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Responding Variable

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the variable that changes in response to the manipulated variable

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Controlled Experiment

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experiment in which only one variable is deliberatly changed at time

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Scientific Theory

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a well tested explanation for a set of observations or experimental results

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Scientific Law

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a statement that summarizes a pattern found in nature

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Model

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representation of an object

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Scientific Notation

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a way of expressing a value as the product of a number between `1 and 10 and a power of 10

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Length

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the straight line distance between two points, is the meter

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Mass

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the quantity of Matter in an object or sample is the kilogram

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Volume

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is the amount of space taken up by an object

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Density

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the ratio of an objects mass to its volume

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Conversion Factor

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a ratio of an equivalent measurements that is used to convert a quantity expressed in one unit to another unit

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Precision

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a gauge of how exact a measurement is

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Significant Figures

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all the digits that are known in a measurement, plus the last digit that is estimated

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Accuracy

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the closeness of a measurement to the actual volume of what is being measured

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Thermometer

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instrument that measures temperature

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Slope

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line is the ratio of a vertical change to the corresponding

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Pure Substance

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simply a substance

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Element

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a substance that cannot be broken down into substances

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Atom

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the smallest particle of an element

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Compound

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a substance that is made from two or more simpler substances and can be broken down into those simpler substances

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Heterogenous Mixtures

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parts of the mixture are noticeably different from one another

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Homogenous Mixtures

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substances are so evenly distributed that is difficult to distuinguish

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Solution

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substances dissolve and form a homogenous mixture

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Suspension

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is a heterogenous mixture that separates into layers over time

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Colloid

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contains some particles that are intermediate in size between the size particles in a solution and the larger particles in a suspension

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Physical Property

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any characteristics of a material that can be observed measured without changing the composition of the substance in the material

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Viscosity

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resistance to flow

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Conductivity

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how well it conducts heat

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Malleability

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the ability of a solid to be hammered without shatering

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Melting Point

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the temperature at which a substance changes from a solid to a liquid

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Boiling point

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the temperature at which a substance boils

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Filiteration

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is a process that separates materials based on the size of their particles

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Distillation

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process that separates the substance in a solution based on their boiling points.

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Physical Change

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occurs when some of the properties of a material change, but the substance in the material remain the same

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Chemical Property

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is any ability to produce a change in the composition of matter

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Flammibility

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is a material's ability to burn in the presence of oxygen

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Reactivity

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the property that describes how readily a substance combines chemically with other substance

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Chemical change

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when a substance reacts and forms one or more new substances

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Precipitant

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any solid that forms and separates and forms and separates from a liquid mixture.

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Solid

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is the state of matter in which materials have a definite shape and a definite volume

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Liquid

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is the state of matter in which a material has a definite shape but no definite volume

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Gas

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the state of matter in which a material has neither a definite shape or definite volume

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Kinetic Energy

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the energy of an object has due to its motion

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Pressure

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the result of a force distributed over an area

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Absolute Zero

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temperatures are equal to 0 degrees on the Kelvin temperature scale

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Charles Law

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states that the volume of a gas is directly proportional to its temperature in kelvins if the pressure and the number of particles of the gas are constant

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Boyles Law

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states that the volume of a gas is inversely proportional to its pressure if the temperature

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Phase Change

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the reversible physical change that occurs when a substance changes from one state of matter to another

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Endothermic

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the system absorbs energy from its surroundings

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Heat of fusion

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amount of energy

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Exothermic

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system releases energy to its surroundings

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Vaporization

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liquid to a gas

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Heat of Vaporization

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amount of energy

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Evaporation

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liquid to a gas at temperature below boiling point

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Vapor pressure

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pressure of water increases as the temperature increases

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Condensation

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the phase change in which a substance changes from a gas to vapor to liquid

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Sublimation

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solid to a gas to vapor to liquid

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Deposition

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gas to solid without turning to liquid

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Proton

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a positively charged subatomic particles in the nucleas of an atom

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Electron

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a negatively charged particle

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Neutron

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a neutral atom

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Atomic Number

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equals the number of protons in an atom

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Mass number

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the sum of the protons and neutrons in the nucleas

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Isotopes

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atoms of the same element have different numbers of neutrons and different mass number

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Periodic Table

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is an arrangement of elements in columns, based on a set of properties that repeat from row to row

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Period

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Each row in the table of Elements

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Group

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each column on the periodic table

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Periodic Law

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pattern of repeating properties

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Atomic Mass Unit

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defined as one twelfth the mass of a carbon-12 atom

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Metals

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elements that are good conductors of electric current and heat

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Transition Metals

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elements that form a bridge between the elements on the left and right side of the table

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Nonmetals

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elements that are poor conductors of heat and electricity.

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Metalloids

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elements with properties that fill between those of metals and non-metals.

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Valence Electrons

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an electron that is in the highest occupied energy levels of an atom

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Alkali metals

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elements in group 1A, single valence electrons, very reactive

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Alkaline Earth Metals

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Group 2A, two valence electrons

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Halogens

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Group 7A, seven valence electrons

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Noble Gases

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Group 8A, Helium has two valence electrons

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Electron Dot Diagram

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a model of an atom in which each dot represents a valence electron.

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Ion

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an atom that has a net of positive or negative electric charge

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Anions

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symbol for the ion is written with a negative sign because an anion is a negative charge

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Cation

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an ion with a positive charge

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Chemical Bond

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is the force that holds cations and anions together

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Ionic Bond

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the force that holds cations and anions together

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Chemical Formula

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a notation that shows what elements a compound contains and the ratio of the atom or ions of the elements in the compound

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Crystals

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Solids whose particles are arranged in a lattrice structure

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Covalent Bond

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a chemical bond in which two atoms share a pair of valence electrons

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Molecule

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a neutral group of atoms that are joined together by one more covalent bonds

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Polar-covalent bonds

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covalent bond in which electrons are not shared equally

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Polyatomic Ions

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a covalently bonded group of atoms that has a positive of negative charge acts as a unit

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Metallic bond

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the attraction between metal cation and the shared electrons that surround it

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Alloy

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a mixture of two or more elements at least one is a metal

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Reactants

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the substance that undergoes changes

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Products

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a new substance that forms as a result

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Chemical Equation

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a representation of a chemical reaction in which the reactants and products

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Coefficient

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numbers that appear before the formulas

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Mole

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an amount of a substance that contains approximately 6.02 x 10^23 particles of that substance

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Molar Mass

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mass of one mole of a substance

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Synthesis Reaction

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a reaction in which two or more substance react to form a single substances react to form a single substance

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Decomposition Reaction

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a reaction in which a compound breaks down into two or more simpler substances

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Single-replacement reaction

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a reaction in which one element takes the place of another element in a compound

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Double-replacement reaction

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one in which two different compounds exchange positive ions and form two new compouds

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Combustion Reaction

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one in which two different compounds exchange positive ions and form two new compounds.

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Combustion Reaction

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one in which a substance reacts rapidly with oxygen, producing heat and light

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Oxidation

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reduction reaction redox reaction

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Chemical energy

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energy stored in the chemical bonds of a substance

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Exothermic Reaction

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chemical reaction that releases energy to its surroundings

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Endothermic Reaction

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chemical reaction that absorbs energy from its surroundings

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Reaction Rate

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the rate at which reactants change

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Catalyst

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a substance that affects the reaction rate without being used up in the reaction

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Equilbrium

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a state in which the forward and reverse paths of a change take place at the same rate

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Reversible Reaction

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a reaction in which the conversion of reactants into products and the conversion of products into product into products into reactants can happen simultaneosly