1. Matter and Change
Chapter 1

2. Theoretical Chemistry
Branches of Chemistry
Organic Chemistry
Inorganic Chemistry
Physical Chemistry
Analytical Chemistry
Biochemistry
Theoretical Chemistry
….and many more!

3. anything that has mass and takes up space
Matter
anything that has mass and takes up space
pure substances – compounds and elements
mixtures – two or more pure substances mixed in the same container…not bonded

4. Pure Substances
Element – A pure substance made of only one kind of atom Atom – An atom is the smallest unit of an element that maintains the properties of that element

5. Pure Substances
Compound – A substance that is made from the atoms of two or more elements that are chemically bonded.
Molecule – the smallest unit of an element or compound that retains all of the properties of that element or compound

6. How can a molecule describe an element?
Huh?
How can a molecule describe an element?

7. H2, Br2,O2, F2, I2, N2, Cl2, Diatomic Elements Uncle Henry BrOFINCl
These elements are found as a pair, chemically bonded to one another. They are not always in pairs in a compound but are in pairs when they are found as the pure element. Ex: H2O (only 1 oxygen)

8. Compounds and Elements

9. space filling model
molecular model
chemical formula
structural formula

10. SHAPE
definite shape
indefinite shape
VOLUME
definite volume
indefinite volume
Solid
Liquid
Gas

11. States of Matter
The particles of a solid are packed together in relatively fixed positions.
The particles have strong attractive forces and low energy.
(s)

12. Solids Solids are in a relatively fixed position.
Solids have only vibrational movements around fixed points.
Solids have definite shape and volume.
Solids are almost incompressible.
Solids do not diffuse (practically).

13. Solids Solids are either crystalline or amorphous.
crystalline – consist of crystals, particles arranged in an orderly, geometric repeating pattern
amorphous – Greek for “without shape”; consist of particles, randomly arranged

14. Crystalline Solids NaCl is cubic.
Crystalline solids break into orderly pieces. After breaking salt, the cubic structure is still visible.

15. Crystalline Solids
crystal structure – three-dimensional arrangement of particles of a crystal, represented by a lattice
unit cell – The smallest portion of a crystal lattice that shows the 3-D pattern

16. Crystalline Systems

17. Amorphous Solids Amorphous solids break into random pieces.
They usually shatter into irregular shapes.
Most plastics are amorphous.

18. Amorphous Solids
The freezing point of amorphous solids can vary according to how slowly the material cools. (Ex: butter)

19. States of Matter
The particles of a liquid are close together but can most past one another.
These particles have more energy than those of a solid, and this energy is what allows a liquid to flow.
Pure liquid = (l)
A liquid solution = (aq)

20. Liquids
LIQUIDS…
have a definite volume and take on the shape of their container (unlike gases)
have a high density
are not compressed well (brake fluid)
diffuse (like food coloring in water)
have surface tension
are fluids (but fluid ¹ liquid)

21. Liquids
surface tension – a force that tends to pull adjacent parts of a liquid’s surface together, thereby decreasing surface area to the smallest possible size.
Surface tension results from attractive forces between the particles in the liquid. The stronger the attractive force, the higher the surface tension.

22. Liquids
Notice that the “pull” on the mercury atoms at the top is not symmetrical. That is what gives the characteristic spherical shape to drops of liquid.

23. Liquids viscosity – the resistance of a liquid to flow
high viscosity = “thick” liquid
low viscosity = “thin” liquid
Liquids with stronger intermolecular forces have higher viscosity.
An increase in temperature will decrease the viscosity.

24. Liquids
volatile liquid - a liquid that evaporates readily at low temperatures
The higher the volatility of a liquid, the weaker the intermolecular forces of attraction between their particles.
An increase in T will increase evaporation.

25. Liquids cohesive forces
In each cylinder, can you describe which forces are greater: cohesive or adhesive?
cohesive forces
forces of attraction between like molecules (H2O to H2O)
adhesive forces
forces of attraction between unlike molecules (H2O to glass)

26. Liquids
capillary action - the attraction of the surface of a liquid to the surface of a solid (adhesive forces)
Many liquids will “creep” along a solid, like water does to paper or cloth fibers until the pull of gravity is too much for it to overcome.

27. States of Matter
The particles of a gas move rapidly past one another, and are at a great distance apart from one another compared to their size.
These particles have very high energy.
(g)

28. States of Matter - Plasma
A plasma is a very high temperature physical state of matter in which atoms lose their electrons.
Plasma is found in fluorescent light bulbs and plasma Televisions.

29. Solid, Liquid, or Gas?

33. What happens
during a
phase change?

34. The Kinetic Theory of Heat and Temperature
When a phase change is occurring, the temperature does not change, only the position of the particles. (PE)
When something is being heated and it is not changing phase, the temperature will rise. (KE)

35. Potential Energy Differences
PE – “energy of position”

36. THERE IS NO TEMPERATURE CHANGE DURING A PHASE CHANGE.
PE vs. KE
Only differences in kinetic energy are reflected by temperature differences.
Difference in potential energy are NOT reflected in temperature differences.
THERE IS NO TEMPERATURE CHANGE DURING A PHASE CHANGE.

37. Phase Changes During solidification or melting
DH = Kfm
Kf = heat of fusion, the amount of heat needed to melt/freeze 1g of a substance
During boiling or condensing
DH = Kvm
Kv = heat of vaporization, the amount of heat needed to boil/condense 1g of a substance

38. Phase Changes
Kf for water = 333 J/g
Kv for water = 2260 J/g

39. Heating Curve for Water

40. Phase Diagrams CRITICAL PRESSURE CRITICAL POINT TRIPLE POINT CRITICAL
(the lowest
pressure at
which the
substance
can still be
a liquid at
the
critical T)
CRITICAL POINT
TRIPLE POINT
CRITICAL
TEMPERATURE
(no more liquids
above this)

41. Phase Diagram for Water

42. What two phase changes are occurring at the same time?

43. Physical Properties
physical property – a characteristic that can be observed or measured without changing the identity of the substance
state of matter
melting point
mass
color

44. Physical Changes
physical change – a change in a substance that does not involve a change in the identity of the substance
breaking
cutting
dissolving
boiling
tearing

45. All phase changes are physical changes.

46. Chemical Properties
chemical property – a characteristic that can be observed or measured with a change in the identity of the substance
flammability
reacts with an acid
reacts with oxygen

47. Chemical Changes
chemical change – a change in a substance that does involve a change in the identity of the substance
color change
gas released (often with an odor)
energy change (light, heat, …)
precipitate formed
…four good indications of a chemical change.

48. Precipitate aqueous – dissolved in water
precipitate – a solid formed from two aqueous solutions during a chemical reaction

49. Extensive vs. Intensive Properties
extensive – DOES depend on the amount of matter present
Examples: mass, volume, amount of energy within a substance
intensive – does NOT depend on the amount of matter present
Examples: color, melting point, density, luster
If mass and volume are extensive properties, why is density an intensive property?

50. Classification of Matter

51. Decomposition of Water
water ® hydrogen + oxygen
2H2O(l) ® 2H2(g) + O2(g) +
reactants
yield
products

52. Hoffman Apparatus
The Hoffman Apparatus is used to decompose water into its pure elements. This is a chemical change. The new substances (hydrogen gas and oxygen gas) did not retain the properties of the original substance (water).
Watch this video!

53. Heterogeneous Mixtures
Homogeneous Mixtures
the same throughout…each sample contains the same ratio of ingredients
(Also called solutions)
Heterogeneous Mixtures
different throughout…each sample contains a different ratio of ingredients

54. Separation of Mixtures
density
PHYSICAL changes only
magnetism
by hand
evaporation
filtration
chromatography

55. Separation of elemental Fe
magnetism
This doesn’t work with iron that is bound into a compound, only with elemental Fe.

56. Distillation Apparatus

57. Mixture or Pure Substance?

58. Homogeneous Mixture, Heterogeneous Mixture or Pure Substance?