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25 Cards in this Set
- Front
- Back
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endothermic change
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a change in which energy is taken in (ex. melting of ice)
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law of conservation of matter
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the fact that matter is not created or destroyed in any chemical or physical change
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element
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a pure substance that cannot be broken down into another substance
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matter
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anything that has mass and takes up space
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chemical energy
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energy stored in the chemical bonds between atoms
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chemical change
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a change in matter that produces one or more new substances
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thermal energy
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the most common form of energy released or absorbed
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homogeneous mixture
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substances so evenly mixed that you can't see the different parts (like water).
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physical properties
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the ability to dissolve in water and to conduct electricity
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how does physical change differ from a chemical change?
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physical change is still same substance after change, chemical change produces one or more new substances
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how do you know that the burning of candle wax is a exothermic change?
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it releases energy in the form of heat and light
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liquid
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substance with a definite volume but no definite shape
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condensation
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process in which a gas cools and becomes a liquid
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freezing
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particles in liquid move so slowly, takes on fix positions
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vaporization
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particles in liquid gain enough energy to move independently,
forming gas |
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describe the motion of particles in a solid.
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the particles are closely locked in position and can only vibrate
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why are both liquids and gases called fluids?
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particles not bonded and able to flow freely
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describe four examples of changes in state.
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melting, freezing, vaporization, and evaporation
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what happens to water molecules when water is heated from 90c to 110c?
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vaporized molecules forms bubbles below surface, bubbles rise and break down surface.
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atomic number
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the number of protons in the nucleus of an atom.
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periods
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the horizontal rows in the periodic table
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alkali metals
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on periodic table, the group that contains elements that are most reactive
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how do two isotopes of an element differ from one another?
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they have different number of neutrons
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valence electrons in an atom are those that are
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held most loosely
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an electron dot diagram shows
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an atom's number of valence electrons
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