Chemistry IChapter 3

Matter Properties and Change

1.)What is a pure substance?

Matter that has a uniform and unchanging composition

2.)What is a physical property?

A characteristic that can be observed or measured without changing the composition of the substance.

Examples of physical properties include: density, color, odor, taste, hardness, melting point and boiling point

3.)What are the two types of physical properties?extensive and intensive

4.)What are extensive properties?Extensive properties are dependent on the amount of substance present.

i.e., length, volume, mass

5.)What are intensive properties?Intensive properties are independent of the amount of substance present.

i.e., density, melting point, boiling point

6.)What type of physical property can be used to identify a pure substance?Intensive properties

7.What is a chemical property?The ability of a substance to

combine with or change into one or more substances. Also, the inability of a substance to change into another substance is a chemical property.

8.)What are the four states of matter in order of increasing energy?solid →liquid→gas →plasma

9.)Describe the solid state• Definite shape and volume• Particles are tightly packed• incompressible

10.)Describe the liquid state

• Particles of matter can flow past one another.

• Constant volume• Takes the shape of the

container• incompressible

11.)Describe the gas phase• Fills the entire volume of its

container• Particles are far apart • Gases are compressible

12.)Describe the plasma phase• Energy level is so high that intact atoms do not exist; protons and electrons are separated.

• Most common phase in the universe, but is not common on earth.

• Found in lightening strikes or in electrical sparks.

Changes in Matter

13.)What are physical changes?Changes that alter the

appearance of a substance without changing its composition.

All changes of phase are physical changes.

13.)What are physical changes?

*ice → water → steam

Still water (H2O)*Nitrogen gas is cooled and

become liquid nitrogen, but its still pure N2

*Crumpled aluminum foil is still aluminum

Examples of physical changes?

Melting, freezing, boiling, bending, grinding, crumpling, splitting, crushing

14.)What are chemical changes?A process that involves

one or more substances changing into new substances.

Something new is formed.

15.)What are some terms that imply that a chemical reaction has occurred?Combust, rust, explode,

corrode, tarnish, ferment, burn, decompose

16.)What are some signs that a chemical reaction has occurred?Evolution of a gasColor changeChange of temperatureFormation of a precipitateChange in magnetic

properties

17.)What is the Law of Conservation of Mass?Mass is neither created

nor destroyed during a chemical reaction. It is conserved.

What is the Law of Conservation of Mass?

For example

2HgO → 2 Hg + O2

432g = 400 g + 32g

reactant products

Mixtures of Matter

18.)What is a mixture?A combination of two or more pure substances in which each pure substance retains its individual chemical properties

What is a mixture?For example,Stew – carrots, potatoes and beef

Air – oxygen, nitrogen, carbon dioxide and water vapor

19.)What are the two classifications of mixtures?1.) Heterogenous- does not blend smoothly, individual substances remain distinct.

Stew, concrete

What are the two classifications of mixtures?2.) homogeneous- has a constant composition through ( the same)

Air, saline

20.)What is another name for a homogeneous mixture?A solution

21.) Types of solutionsgas – gas: airgas – liquid: CO2 in sodaliquid- gas: moist humid airliquid – liquid: vinegar and

watersolid- liquid: sugar watersolid – solid: steel

22.)What are some methods that may be used to separate mixtures?Filtration- uses a porous

barrier to separate liquid and solid.

i.e., sand and water

22.)What are some methods that may be used to separate mixtures?Magnetic propertiesSulfur and iron filings

22.)What are some methods that may be used to separate mixtures?Distillation- a separation

technique that is based on differences in boiling points

i.e., alcohol and water

22.)What are some methods that may be used to separate mixtures?Chromotography – a separation technique that separates the components of a mixture ( called the mobile phase) on the basis of the tendency of each to travel or be drawn across the surface of another (called the stationary phase)

22.)What are some methods that may be used to separate mixtures?Crystallization a separation technique that results in particles of a substance from a solution containing the dissolved substance.

Crystallization produces highly pure solids.

Elements and Compounds

23.)What are the two subdivisions of all pure substances?

Elements and compounds

24.) What is an element?An element is a pure substance that cannot be separated into simpler means by chemical or physical means.

25.)How many naturally occurring elements are there?91

26.)What are the trans-uranium elements?No elements past uranium

are naturally occurring. These elements are unstable and must be made synthetically in the laboratory.

27.)How are the elements represented by chemical symbols?Most symbols are 1 or 2

letters. The first letter must be capitol, the second must be lower case.

28.)What is the periodic table?The periodic table

organizes the elements into a grid of horizontal rows and vertical columns based on chemical and physical similarities and trends.

29.)What do we call the vertical columns?

The columns are called groups or families.

30.)What is significant about the elements in the same family or group?

These elements have similar properties.

31.)Who is credited with designing the first periodic table?The Russian

chemist/professor

Dmitri Mendeleev

32.)What is significant about the empty spaces that Mendeleev left on his original periodic table?Mendeleev left empty spaces

for elements he believed had yet to be discovered. He predicted the properties of these elements before they were discovered.

32 contd. What is significant about the empty spaces that Mendeleev left on his original periodic table?When the discovered elements matched the predicted properties, it gave support for the periodic table as a valid tool.

33.)What is a compound?A combination of two or

more different elements that are chemically combined.

A compound can be broken down into simpler substances by chemical or physical means.

34.) How are chemical symbols used to indicate the number of atoms of each element?The symbol is written 1st . The

# of atoms of each element is written as a subscript after the symbol. If only one atom is present the 1 is not written.

34 contd. How are chemical symbols used to indicate the number of atoms of each element?CO2 1 carbon;2 oxygen

34 contd.How are chemical symbols used to indicate the number of atoms of each element?If parenthesis are used, the

subscript after the parenthesis applies only to the elements in the parenthesis.

34 contd. How are chemical symbols used to indicate the number of atoms of each element?Ca(NO3)2 1 calcium; 2

nitrogen; 6 oxygen

Ca3(PO4)2 3 calcium; 2 phosphorus; 8 oxygen

35.) How do the properties of a compound compare to the elements that make it up?They are very different.

H2O liquid water at room temp.

H2 gas at room temp.

O2 gas at room temp.

36.) What are two ways that a compound can be broken down into simpler substances by physical means.Electrolysis (passing an

electric current through the substance) and heating it.

37.) What is the classification diagram of all matter?

38.)What is the Law of Definite Proportions?

Regardless of the amount, a compound is always composed of the same elements in the same proportions by mass.

39.)How do you find % mass?

% mass = mass of element x 100

mass of compound

Sucrose analysis – 20 gram sample

Column 1 Column 2

Element Analysis by mass(g)

% by mass

carbon 8.44 g 8.44/20.0 x 100 = 42.2 %

hydrogen 1.30 g 1.30/20.0 x 100 = 6.50%

oxygen 10.26 g 10.26/20.0 x 100 = 51.30%

total 20.0 g 100.0 %

Sucrose analysis – 500 gram sample

Column 1 Column 2

Element Analysis by mass(g)

% by mass

carbon 211.0 g 211.0/500.0 x 100 = 42.2 %

hydrogen 32.5 g 32.5/500.0 x 100 = 6.50%

oxygen 256.6 g 256.6/500.0 x 100 = 51.30%

total 500.0 g 100.0 %

40.)What is the Law of Multiple Proportions?When different

compounds are formed by a combination of the same elements,different masses of one element combine with the same relative mass of the other.

For example, compare water H2Oand peroxide H2O2.Compare masses

H2O 2 amu: 16 amu

11%: 89%H2O2 2 amu; 32 amu

0.06%: 94%

41.) What formula is used to show the Law of Multiple Proportions?Mass ratio of compound I

Mass ratio of compound II

11/89 = .12 = 2

.06/94 .06

For example, compare water H2Oand peroxide H2O2.Mass ratio of compound I

Mass ratio of compound II

11/89 = .12 = 2

.06/94 .06

Law of Multiple Proportions exampleCompound %

Cu% Cl Mass

Cu (g) in 100g

Mass Cl (g) in 100g

Mass ratio mass Cu

Mass Cl

I 64.20 35.80 64.20 35.80 1.793

II 47.27 52.73 47.27 52.73 .08964

Law of Multiple Proportions example

Mass ratio compound I = 1.793 = 2

Mass ratio compound II 0.8964