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32 terms

Science Terms Test 1

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Pure Substance
Matter, either a single element or a single compound- (made of one kind of particle), that has definite chemical and physical properties. Ex: Gold or Carbon dioxide
Heterogeneous Mixture
a mixture in which the composition is not uniform throughout, the substances are not evenly distributed
Homogeneous Mixture
a mixture in which the composition is uniform throughout, the substances are evenly distributed
Element
A substance that contains only a single type of atom-each element is made of a specific type of atom, but not a certain number of atoms. Ex: Gold
Compound
A substance that consists of two or more different types of atoms bonded together. Ex: Carbon Dioxide (CO2)
Atom
The smallest basic unit of matter
Molecule
A particle made of two or more atoms bonded together, or combined Ex: Water (H20)
Physical Change
A change in any physical property of a substance, not the substance itself Ex: Breaking a piece of clay
Chemical Change
The change of one substance into another substance. During chemical change, combinations of atoms in the original substances are rearranged to make new substances. Ex: Burning
Physical Properties
The characteristics of a substance that can be observed without changing the identity of the substance: Ex: Texture
Chemical Properties
Properties that describe how substances can form new substances. Ex: Combustibility
Evidence of Change
Evidence that proves a substance has gone through a (chemical or physical) change Ex: for chemical change . . . Production of Odor, Change in Temperature, Change in Color, Formation of Bubbles, Formation of a Solid
Evaporation
A process by which a liquid becomes a gas. Caused by an increase in temperature which causes the substance to gain energy. Usually occurs at the surface of a liquid.. Occurs over time.
Condensation
The process by which a geas changes its state to become a liquid. Caused by a decrease in temperature which causes the substance to loose energy.
Freezing
The process by which a liquid becomes a solid. Caused by a decrease in temperature.
Melting
The process by which a solid becomes a liquid. Is caused by an increase in temperature.
Boiling
The process by which a liquid becomes a gas. Is caused by an increase in temperature.
Melting Point
The lowest temperature at which a substance begins to melt.
Boiling Point
The lowest temperature at which a substance begins to boil.
Sublimation
When a solid changes from directly into a gas. This only occurs under certain conditions. Ex: Dry Ice
Dissolve
The process in which the particles of a substance (solute) are separated and absorbed into another substance (solvent).
Solution
A type of mixture that is a homogeneous mixture. Can be physically separated, but all portions of a solution have the same properties when they are still combined.
Solvent
A substance that dissolves a solute.
Solute
A substance that is dissolved (by the solvent) to make a solution.
Saturated
When a solution contains the maximum amount of solute that can be dissolved in the solvent at a given temperature.
Concentrated
An adjective describing a mixture that has more solute than solvent.
Dilute
An adjective describing a mixture that has more solvent than solute.
Concentration
Mass of Solute (in grams) divided by the mass of Solvent (in milliliters). Depends on the amount of solute dissolved into the solvent at a particular temperature.
Precipitate
A solid (the solute) that forms and settles out of a solution when the solution contains more than the solubility of solute at a certain temperature.
Solubility
The amount of a substance that will dissolve in a certain amount of solvent at a given temperature.
Solubility Curve
A graph showing the change in the solubility of a substance corresponding to the change in temperature- it can be seen that the solubility increases with the temperature and each substance increases at different rates.
Distillation
A process used to separate dissolved solids from a liquid, which is boiled to produce a vapor that is then condensed into a liquid