1. Properties of Matter—Substances
Matter—Properties and Change: Basic Concepts
Topic 4
Properties of Matter—Substances
Matter that has a uniform and unchanging composition is called a substance, also known as a pure substance.
Table salt is a substance.
Another example of a pure substance is water.
Water is always composed of hydrogen and oxygen.

2. Properties of Matter—Substances
Matter—Properties and Change: Basic Concepts
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Properties of Matter—Substances
Seawater, on the other hand, is not a substance because samples taken from different locations will probably have differing compositions.

3. Physical Properties of Matter
Matter—Properties and Change: Basic Concepts
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Physical Properties of Matter
A physical property is a characteristic that can be observed or measured without changing the sample’s composition. Physical properties describe pure substances, too.
Because substances have uniform and unchanging compositions, they have consistent and unchanging physical properties as well.

4. Physical Properties of Matter
Matter—Properties and Change: Basic Concepts
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Physical Properties of Matter
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5. Physical Properties of Matter
Matter—Properties and Change: Basic Concepts
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Physical Properties of Matter
density,
taste,
color,
hardness,
odor,
melting point,
and boiling point are common physical properties that scientists record as identifying characteristics of a substance.

6. Extensive and Intensive Properties
Matter—Properties and Change: Basic Concepts
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Extensive and Intensive Properties 
Physical properties can be further described as being one of two types.
Extensive properties are dependent upon the amount of substance present. Mass is an extensive property.
Length and volume are also extensive properties.

7. Extensive and Intensive Properties
Matter—Properties and Change: Basic Concepts
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Extensive and Intensive Properties 
Intensive properties are independent of the amount of substance present.
For example, the density of a substance is the same no matter how much substance is present.

8. Chemical Properties of Matter
Matter—Properties and Change: Basic Concepts
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Chemical Properties of Matter
The ability of a substance to combine with or change into one or more other substances is called a chemical property.
The ability of iron to form rust when combined with air is an example of a chemical property of iron
The fact that iron does not undergo a change in the presence of nitrogen is another chemical property of iron.

9. Observing Properties of Matter
Matter—Properties and Change: Basic Concepts
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Observing Properties of Matter
Every substance has its own unique set of physical and chemical properties.

10. Matter—Properties and Change: Basic Concepts
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States of Matter
In fact, all matter that exists on Earth can be classified as one of these physical forms called states of matter.
Scientists recognize a fourth state of matter called plasma, but it does not occur naturally on Earth except in the form of lightning bolts.

11. Matter—Properties and Change: Basic Concepts
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States of Matter
The physical state of a substance is a physical property of that substance.
Each of the three common states of matter can be distinguished by the way it fills a container.

12. Wood, iron, paper, and sugar are examples of solids.
Matter—Properties and Change: Basic Concepts
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Solids
A solid is a form of matter that has its own definite shape and volume.
Wood, iron, paper, and sugar are examples of solids.

13. Matter—Properties and Change: Basic Concepts
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Solids
The particles of matter in a solid are very tightly packed; when heated, a solid expands, but only slightly.
A solid does not conform to the shape of the container in which it is placed.

14. Common examples of liquids include water, blood, and mercury.
Matter—Properties and Change: Basic Concepts
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Liquids 
A liquid is a form of matter that flows, has constant volume, and takes the shape of its container.
Common examples of liquids include water, blood, and mercury.
The particles in a liquid are not rigidly held in place and are less closely packed than are the particles in a solid: liquid particles are able to move past each other.

15. Matter—Properties and Change: Basic Concepts
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Liquids 
This allows a liquid to flow and take the shape of its container, although it may not completely fill the container.

16. Matter—Properties and Change: Basic Concepts
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Liquids 
Because of the way the particles of a liquid are packed, liquids are virtually incompressible. Like solids, liquids tend to expand when heated.

17. Matter—Properties and Change: Basic Concepts
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Gases
A gas is a form of matter that flows to conform to the shape of its container and fills the entire volume of its container.
Compared to solids and liquids, the particles of gases are very far apart.
Because of the significant amount of space between particles, gases are easily compressed.

18. Matter—Properties and Change: Basic Concepts
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Gases
The word gas refers to a substance that is naturally in the gaseous state at room temperature.

19. The state of matter is a physical property.
Matter—Properties and Change: Basic Concepts
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Gases
The fact that substances can change form is another important concept in chemistry
The state of matter is a physical property.

20. Matter—Properties and Change: Basic Concepts
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21. Matter—Properties and Change: Basic Concepts
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Physical Changes
A substance often undergoes changes that result in a dramatically different appearance yet leave the composition of the substance unchanged.
Changes such as this, which alter a substance without changing its composition, are known as physical changes.

22. Matter—Properties and Change: Basic Concepts
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Physical Changes
Melting and formation of a gas are both physical changes and phase changes.
When you encounter terms such as boil, freeze, condense, vaporize, or melt in your study of chemistry, the meaning generally refers to a phase change in matter.

23. Matter—Properties and Change: Basic Concepts
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Chemical Changes
Chemical properties relate to the ability of a substance to combine with or change into one or more substances.
A process that involves one or more substances changing into new substances is called a chemical change, which is commonly referred to as a chemical reaction.

24. Matter—Properties and Change: Basic Concepts
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Chemical Changes
The new substances formed in the reaction have different compositions and different properties from the substances present before the reaction occurred.

25. Rust is a chemical combination of iron and oxygen.
Matter—Properties and Change: Basic Concepts
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Chemical Changes
Rust is a chemical combination of iron and oxygen.
In chemical reactions, the starting substances are called reactants and the new substances that are formed are called products.

26. Thus iron and oxygen are reactants and rust is a product.
Matter—Properties and Change: Basic Concepts
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Chemical Changes
Thus iron and oxygen are reactants and rust is a product.
When you encounter terms such as explode, rust, oxidize, corrode, tarnish, ferment, burn, or rot, the meaning generally refers to a chemical reaction in which reactant substances produce different product substances.

27. Matter—Properties and Change: Basic Concepts
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Conservation of Mass
By carefully measuring mass before and after many chemical reactions, it was observed that, although chemical changes occurred, the total mass involved in the reaction remained constant.
The constancy of mass in chemical reactions was observed so often that scientists assumed the phenomenon must be true for all reactions.

28. Conservation of Mass Topic 4
Matter—Properties and Change: Basic Concepts
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Conservation of Mass
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29. Matter—Properties and Change: Basic Concepts
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Conservation of Mass
The law of conservation of mass states that mass is neither created nor destroyed during a chemical reaction—it is conserved.
The law of conservation of mass is one of the most fundamental concepts of chemistry.

30. The equation form of the law of conservation of mass is:
Matter—Properties and Change: Basic Concepts
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Conservation of Mass
The equation form of the law of conservation of mass is:

31. Matter—Properties and Change: Additional Concepts
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Mixtures
A mixture is a combination of two or more pure substances in which each pure substance retains its individual chemical properties.
The composition of mixtures is variable, and the number of mixtures that can be created by combining substances is infinite.

32. Substances tend naturally to mix; it is difficult to keep things pure.
Matter—Properties and Change: Additional Concepts
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Mixtures
Although much of the focus of chemistry is the behavior of substances, it is important to remember that most everyday matter occurs as mixtures.
Substances tend naturally to mix; it is difficult to keep things pure.

33. The sand and water mixture is an example of a heterogeneous mixture.
Matter—Properties and Change: Additional Concepts
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Types of Mixtures
Mixtures themselves are classified as either heterogeneous or homogeneous.
A heterogeneous mixture is one that does not blend smoothly throughout and in which the individual substances remain distinct.
The sand and water mixture is an example of a heterogeneous mixture.

34. The drop would be almost completely water.
Matter—Properties and Change: Additional Concepts
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Types of Mixtures
Suppose you draw a drop from the top of a mixture of sand and water using an eyedropper.
The drop would be almost completely water.

35. Matter—Properties and Change: Additional Concepts
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Types of Mixtures
If you draw a second drop from the bottom of the mixture, that drop would contain mostly sand.
Thus the composition of the sand–water mixture is not uniform—the substances have not blended smoothly and the two substances of the mixture (sand on the bottom and water on the top) remain distinct.

36. Let’s examine a salt–water mixture using the eyedropper.
Matter—Properties and Change: Additional Concepts
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Types of Mixtures
A homogeneous mixture has constant composition throughout; it always has a single phase.
Let’s examine a salt–water mixture using the eyedropper.
Every drop of the mixture contains the same relative amounts of salt and water.

37. Homogeneous mixtures are also referred to as solutions.
Matter—Properties and Change: Additional Concepts
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Types of Mixtures
Homogeneous mixtures are also referred to as solutions.

38. Solutions may contain solids, liquids, or gases,
Matter—Properties and Change: Additional Concepts
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Types of Mixtures
Solutions may contain solids, liquids, or gases,

39. The solid–solid solution is called an alloy. (ex steel)
Matter—Properties and Change: Additional Concepts
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Types of Mixtures
The solid–solid solution is called an alloy. (ex steel)

40. Most matter exists naturally as mixtures.
Matter—Properties and Change: Additional Concepts
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Separating Mixtures
Most matter exists naturally as mixtures.
Because the substances in a mixture are physically combined, the processes used to separate a mixture are based on differences in physical properties of the substances.

41. Matter—Properties and Change: Additional Concepts
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Separating Mixtures
Filtration is a technique that uses a porous barrier to separate a solid from a liquid.

42. Most homogeneous mixtures can be separated by distillation
Matter—Properties and Change: Additional Concepts
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Separating Mixtures
Most homogeneous mixtures can be separated by distillation
Distillation is a separation technique that is based on differences in the boiling points of the substances involved.

43. Matter—Properties and Change: Additional Concepts
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Separating Mixtures
Crystallization is a separation technique that results in the formation of pure solid particles of a substance from a solution containing the dissolved substance.

44. Matter—Properties and Change: Additional Concepts
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Separating Mixtures
Chromatography is a technique that separates the components of a mixture on the basis of their tendency to be drawn across the surface of another material.
The separation occurs because the various components of the ink spread through the paper ant different rates.

45. Matter—Properties and Change: Additional Concepts
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Elements
An element is a pure substance that cannot be separated into simpler substances by physical or chemical means.

46. Each element has a unique chemical name and symbol.
Matter—Properties and Change: Additional Concepts
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Elements
Each element has a unique chemical name and symbol.
The chemical symbol consists of one, two, or three letters; the first letter is always capitalized and the remaining letter(s) are always lowercase.

47. Matter—Properties and Change: Additional Concepts
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Elements
As new elements were being discovered chemists began to see patterns of similarities in the properties of sets of elements.
In 1869, the Russian chemist Dmitri Mendeleev devised the chart which organized all of the known elements into rows and columns based on their similarities and their masses.

48. Matter—Properties and Change: Additional Concepts
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Elements
Mendeleev’s organizational table was the first version of the periodic table of elements.
The periodic table organizes the elements into a grid of horizontal rows called periods and vertical columns called groups or families.

49. Matter—Properties and Change: Additional Concepts
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Elements
Elements in the same group have similar chemical and physical properties.
The table is called “periodic” because the pattern of similar properties repeats as you move from period to period.

50. Matter—Properties and Change: Additional Concepts
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Periodic Table

51. Most of the substances that you are familiar with are compounds.
Matter—Properties and Change: Additional Concepts
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Compounds
A compound is a combination of two or more different elements that are combined chemically.
Most of the substances that you are familiar with are compounds.
Water, table salt, table sugar, and aspirin are examples of common compounds.

52. Categories of Matter Topic 4
Matter—Properties and Change: Additional Concepts
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Categories of Matter

53. Matter—Properties and Change: Additional Concepts
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Compounds
The chemical symbols of the periodic table make it easy to write the formulas for chemical compounds.
For example, table salt, or sodium chloride, is composed of one part sodium (Na) and one part chlorine (Cl), and its chemical formula is NaCl.
Water is composed of two parts hydrogen (H) to one part oxygen (O), and its formula is H2O.

54. Matter—Properties and Change: Additional Concepts
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Compounds
Unlike elements, compounds can be broken down into simpler substances by chemical means.
In general, compounds that naturally occur are more stable than the individual component elements.

55. Matter—Properties and Change: Additional Concepts
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Compounds
The properties of a compound are different from those of its component elements.

56. Law of Definite Proportions
Matter—Properties and Change: Additional Concepts
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Law of Definite Proportions
An important characteristic of compounds is that the elements comprising them combine in definite proportions by mass.
This observation is so fundamental that it is summarized as the law of definite proportions.
This law states that, regardless of the amount, a compound is always composed of the same elements in the same proportion by mass.

57. Law of Definite Proportions
Matter—Properties and Change: Additional Concepts
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Law of Definite Proportions
The mass of the compound is equal to the sum of the masses of the elements that make up the compound.
The ratio of the mass of each element to the total mass of the compound is a percentage called the percent by mass.

58. Law of Multiple Proportions
Matter—Properties and Change: Additional Concepts
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Law of Multiple Proportions
The law of multiple proportions states that different compounds can be formed by a combination of the same elements. The elements are combined in different ratios.
Ratios compare the relative amounts of any items or substances.

59. Law of Multiple Proportions
Matter—Properties and Change: Additional Concepts
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Law of Multiple Proportions
Hydrogen peroxide is composed of two parts hydrogen and two parts oxygen. (2:2)
Hydrogen peroxide differs from water in that it has twice as much oxygen.
When we compare the mass of oxygen in hydrogen peroxide to the mass of oxygen in water, we get the ratio 2:1.