1. atom

2. atom
the smallest component of an element having the  chemical properties of the element,  consisting of a nucleus  containing combinations of neutrons and  protons and one or  more electrons bound to the nucleus by electrical attraction; the number of protons determines the identity of the element. 
a small particle that is the building block of matter; the smallest piece of an element that still represents that element.

3. chemical property

4. chemical property
Chemistry. a property or characteristic of a  substance that is observed during a reaction in which the  chemical composition or identity of the  substance is changed.

5. matter

6. matter
something that has mass and occupies space.

7. electron

8. electron
an elementary particle having a negative charge and existing independently or as the component outside  the nucleus of an atom.

9. mass

10. mass
 is a measure of the number of atoms in it.

11. molecule

12. molecule
the smallest physical unit of an element or compound.

13. nucleus

14. nucleus
a central part about which other parts are grouped or gathered; core.
the positively charged mass within an atom,  composed of neutrons and protons, and possessing most of the mass but occupying only a small fraction of the volume of the atom.

15. proton

16. proton
a positively charged elementary particle.

17. temperature

18. temperature
a measure of the warmth or coldness of an object or substance with reference to some standard value. 

19. physical property

20. physical property
a property (as color, hardness, boiling point) of matter not involving in its manifestation a chemical change.

21. boiling point

22. boiling point
the temperature at which a liquid boils.

23. compound

24. compound
composed of two or more parts, elements, or ingredients.

25. density

26. density
mass per unit volume.

27. element

28. element
one of a class of substances that cannot be separated into simpler substances by chemical means.

29. melting point

30. melting point
the temperature at which a solid melts.

31. neutron

32. neutron
an elementary particle having no charge.

33. weight

34. weight
the force that gravitation exerts upon a body, equal to the mass of the body times the local acceleration of  gravity.

35. combustibility

36. combustibility
capable of catching fire and burning;  inflammable; flammable:
Gasoline vapor is highly combustible.

37. malleable

38. malleable
capable of being extended or shaped by  hammering or by pressure from rollers.

39. vapor

40. vapor
a visible exhalation, as fog, mist, steam,  smoke, or noxious gas, diffused through or suspended in the air.

41. chemical reaction

42. chemical reaction
a chemical change that occurs when two or more substances combine to form a new substance.

43. viscosity

44. viscosity
a measurement of a liquid’s resistance to flow.

45. sublimation

46. sublimation
to pass directly from the solid to the vapor state.

47. atomic number

48. atomic number
the number of positive charges or protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.

49. conductor

50. conductor
a substance, body, or device that readily  conducts heat, electricity, sound, etc.

51. pressure

52. pressure
the exertion of force upon a surface by an object, fluid, etc., in contact with it: force per unit area. 

53. periodic table

54. periodic table
a table illustrating the periodic system, in  which the chemical elements arranged according to their atomic numbers, are shown in related  groups.

55. condensation

56. condensation
the act or process of reducing a gas or vapor  to a liquid or solid form.

57. atomic mass

58. atomic mass
the mass of an atom usually expressed in atomic mass units.

59. evaporation

60. evaporation
to convert into vapor; to expel moisture from.

61. vaporization

62. vaporization
the rapid change of water into steam,  especially in a boiler.

63. ductility

64. ductility
capable of being drawn out into wire or  threads, as gold.

65. concentration

66. concentration
the amount of a component in a given area or volume.

67. luster

68. luster
the state or quality of shining by reflecting  light; glitter, sparkle, sheen, or gloss.

69. salinity

70. salinity
consisting of or containing salt.

71. metal

72. metal
any of various opaque, fusible, ductile, and typically lustrous substances that are good conductors of electricity and heat.

73. construct

74. construct
to build or form by putting together parts;  frame; devise.