1. Theories of Matter

2. usually rigid, having definite shape and volume Solids

3. definite volume assume shape of containers but may not fill them can flow under influence of force Liquids

4. low density can flow can completely fill its container easily compressed and rarified Gases

5. exist when the particles of matter have enough kinetic energy that at least some of their electrons become stripped away very high temperatures Plasmas

6. fluid-like, as gases or liquids consist of a neutral mixture of electrons and positively charged particles Plasmas

7. solids, liquids, and gases have been understood for centuries states of matter are difficult to define with precision States of Matter

8. Elements: the basic chemical building blocks of matter cannot be broken down into simpler substances by ordinary means Particles of Matter

9. John Dalton developed atomic theory—matter is made up of atoms now know that atoms can be subdivided Particles of Matter

10. Protons: positively charged particles, found in the nucleus of an atom Neutrons: neutral particles found in the nucleus of an atom Particles of Matter

11. Electrons: negatively charged particles occupying a region of space around the nucleus 1/1860 the mass of a proton Particles of Matter

12. Elementary particles: these make up protons, neutrons, and electons quarks are an example not fully understood Particles of Matter

13. atoms can combine: molecules formula units chemical compounds Particles of Matter

14. Ions: charged particles consisting of one or more atoms with a mismatch between the total numbers of protons and electrons Particles of Matter

15. inconvenient to measure in grams or kilograms relative mass unit atomic mass unit (amu) unified atomic mass unit (u) Atomic Mass

16. Mole: amount of a substance containing 6.022 × 10 23 particles Avogadro’s constant (N A ) or Avogadro’s number Atomic Mass

17. A carbon-12 atom has a mass of 12.00 u. Avogadro’s number of carbon-12 atoms will have a mass of 12.00 g. Atomic Mass

18. Ideal gas model is a good illustration of the kinetic theory Pressure = sum of impulsive forces divided by area of sides Gas Pressure

19. more atoms in the container → greater pressure smaller “area” on which to exert force → greater pressure Gas Pressure

20. greater speed (kinetic energy) of atoms in the container → greater pressure Gas Pressure F = ΔtΔt ΔtΔt 2mv

21. The particles in solids are held rigidly with strong intermolecular force. These particles can vibrate in place. Kinetic Theory

22. The velocity of these vibrations determines the particles’ kinetic energy. Large amounts of kinetic energy are indicated with high temperatures. Kinetic Theory

23. Liquids have particles in close association but with more mobility. Kinetic Theory

24. Cohesion: intermolecular attraction similar particles in a liquid have for each other Kinetic Theory

25. Adhesion: intermolecular attraction between particles of dissimilar materials Kinetic Theory

26. The kinetic theory of matter considers matter as a collection of numerous, extremely tiny particles in continuous motion. Kinetic Theory

27. Although the kinetic theory of matter has limitations, it does a good job predicting the behavior of matter under many conditions. Kinetic Theory

28. States of Matter

29. Arrangement Crystalline solids: particles are held in fixed patterns unit cell NaCl is a good example most metals

30. Arrangement Amorphous solids: particles do not form repeating patterns glass Heterogeneous solids: have combination of crystalline and amorphous solids

31. Elastic Modulus Solids can change shape in response to certain forces Tensile forces tend to pull apart

32. Elastic Modulus Stress (σ): related to the tension force normal (perpendicular) to the cross-sectional area Defined: force per unit area σ = A FF

33. Elastic Modulus Strain (ε): amount stretched (Δl) divided by the initial length (l i ) usually expressed as a simple decimal or percent ε = lili ΔlΔl

34. Elastic Modulus Elastic modulus (E): ratio of the normal stress to the linear strain units: N/m² plural: elastic moduli E = ε σ

35. Elastic Modulus determined experimentally and listed in tables for various substances measure of a material’s resistance to change in shape (stiffness)

36. Elastic Modulus If a wire’s elastic modulus, cross-sectional area, initial length, and the tension exerted on it are known, the change in length can be estimated: Δl = AE F·liF·li

37. Forces Compressive forces: crush or push particles of matter together Shearing forces: tend to cause layers of particles within the solid to slide parallel to each other

38. Shear Modulus Shear stress equals the force exerted parallel to the surface, divided by the surface area. Shear strain is the ratio of deformation of the object parallel to the force, divided by the separation of the two surfaces. Shear modulus (G) is the ratio of shear stress to shear strain: G = shear stress shear strain

39. Stress-Strain Graph

40. Proportional limit: maximum strain without permanent deformation

41. Stress-Strain Graph Elastic limit: limit of reversible deformation

42. Stress-Strain Graph At the fracture point, the object breaks.

43. Stress-Strain Graph Materials work harden when stress is applied in a cyclic way, causing them to become harder or more brittle. This changes the stress- deformation curve.

44. Transitions Melting: from solid to liquid The melting point is usually a predictable temperature at which this occurs

45. Transitions Melting: from solid to liquid A solid’s molecules gain (absorb) enough kinetic energy to break out of their rigid arrangements and move more freely

46. Transitions Melting: from solid to liquid The melting point of a solid also depends on the pressure Water has unusual properties

47. Transitions Water expands when it freezes. higher pressures hinder freezing Regelation: melting under pressure

48. Fluids Liquids and gases are both classified as fluids. no fixed shape assume the shape of their containers can flow under the influence of a force

49. Surface Tension Cohesion at the surface of a liquid pulls the molecules at the surface toward the interior. The net force is inward. This is especially evident with polar molecules like water.

50. Surface Tension explains why water forms into droplets meniscus overflow a glass with water

51. Adhesion a liquid’s surface molecules may be more attracted to an adjoining surface than to each other capillarity liquids flowing into fibrous and porous materials

52. Gas particles are very energetic and widely separated most gases are elements or molecular compounds

53. Vaporization a change of state from solid or liquid to gas Sublimation: directly from solid to gas Boiling: characterized by rapid formation of vapor bubbles within a liquid

54. Vaporization a change of state from solid or liquid to gas Evaporation: vaporization of a liquid below the boiling point and above the freezing point of the liquid

55. Evaporization occurs only at the natural surface of a liquid primary means water uses to return to the atmosphere liquids cool as they evaporate

56. Evaporization in a closed container, a dynamic equilibrium may be reached molecules entering gaseous phase equal in number to those entering liquid phase

57. Evaporization in a closed container, a dynamic equilibrium may be reached vapor pressure: pressure of the gas when the closed system has reached equilibrium

58. Vapor Pressure depends on the kind of liquid and its temperature volatile liquids have low cohesive forces with high vapor pressures

59. Vapor Pressure nonvolatile liquids tend to have lower vapor pressure at a given temperature

60. Condensation vapor goes from the gaseous state to liquid depends on multiple factors

61. Solidification phase transition from liquid to solid also called freezing freezing and melting points are almost always the same for a pure substance

62. Solidification gases can enter the solid phase deposition depends on temperature and other factors

63. Phase Diagrams shows relationships among phases of a substance compared to controlling factors such as pressure and temperature

64. Phase Diagrams Triple point: the combination of temperature and pressure where all three phases of a substance can coexist water: 0.01°C and 0.006 atm