Chemistry Ch 1

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Chemistry Ch 1
2012-08-21 23:50:19
vocabulary chapter

chapter 1
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  1. Accuracy
    How closely a measure value agrees with the correct value.
  2. Atom
    The smallest particle of an element that maintains its chemical identity through all chemical and physical changes.
  3. Atomic number
    The number of protons in the nucleus of an atom.
  4. Calorie
    Defined as exactly 4.184 joules. Originally defined as the wmount of heat required to raise the temperature on one gram of water from 14.5 degreesC to 15.5 degrees C.
  5. Chemical change
    A change in which one or more new substances are formed.
  6. Chemical property
    see properities
  7. Compound
    A substance composed of two or more elements in fixed proportions. Compounds can be decomposed into their constituent elements.
  8. Density
    Mass per unit volume, D=m/V.
  9. Element
    A substance that cannot be decomposed into simpler substances by chemical means. 
  10. Endothermic
    Describes processes that absorb heat energy.
  11. Energy
    The capacity to do work or transfer heat.
  12. Exothermic
    Describes processes that release heat energy.
  13. Extensive property 
    A property that depends on the amount of material in a sample. 
  14. Heat
    A form of energy that flows between two samples of matter because of their difference in temperature.
  15. Heat capacity
    The amount of heat required to raise the temperature of a body one degree Celsius.
  16. Heterogeneous mixture
    A mixture that does not have uniform composition and properties throughout. 
  17. Homogeneous mixture
    A mixture that has uniform composition and properties throughout.
  18. Intensive property
    A property that is independent of the amount of material in a sample. 
  19. Joule
    A unit of energy in the SI system. One joule is 1kg*m2/s2, which is also 0.2390 cal. 
  20. Kinetic energy
    Energy that matter possesses by virtue of its motion.
  21. Law of Conservation of Energy
    Energy cannot be created or destroyed in a chemical reaction or in a physical change; it may be changed from one form to another. 
  22. Law of Conservation of Matter
    No detectable change occurs in the total quantity of matter during a chemical reaction or during a physical change. 
  23. Law of Conservation of Matter and Energy
    The combined amount of matter and energy in the universe is fixed.
  24. Law of Constant Composition
    See Law of Definite Proportions
  25. Law of Definite Proportions
    Different samples of any pure compound contain the same elements in the same proportions by mass; also known as the Law of Contant Composition.
  26. Mass
    A measure of the amount of matter in an object. Mass is usually measured in grams or kilograms.
  27. Matter
    Anything that has mass and occupies space.
  28. Mixture
    A sample of matter composed of variable amounts of two or more substances, each of which retains its identity and properties.
  29. Molecule
    The smallest particle of an element or compound that can have a stable independent existence. 
  30. Physical change
    A change in which a substance changes from one physical state to another, but no substances with different compositions are formed.
  31. Physical property
    See Properties.
  32. Potential energy
    Energy that matter possesses by virtue of its position, condition, or composition.
  33. Precision
    How closely repeated measurements of the same quantity agree with one another.
  34. Properties
    Characteristics that describe samples of matter. Chemical properties are exhibited as matter undergoes chemical changes. Physical properties are exhibited by matter with no changes in chemical composition.
  35. Scientific (natural) law
    A general statement based on the observed behavior of matter, to which no exceptions are known. 
  36. Significant figures
    Digits that indicate the precision of measurements--digits of a measured number that have uncertainty only in the last digit.
  37. Specific gravity
    The ratio of the density of a substance to the density of water at the same temperature. 
  38. Specific heat
    The amount of heat required to raise the temperature of one gram of a substance one degree Celsius. 
  39. Substance
    Any kind of matter all specimens of which have the same chemical composition and physical properties. 
  40. Symbol (of an element)
    A letter or group of letters that represents (identifies) an element.
  41. Temperature
    A measure of the intensity of heat, that is, the hotness or coldness of a sample or object. 
  42. Unit factor
    A factor in which the numerator and denominator are expressed in different units but represent the same or equivalent amounts. Multiplying by a unit factor is the same as multiplying by one. 
  43. Weight
    A measure of the gravitational attraction of the earth for a body.