1. Pure substance or a mixture?
Chemistry and Matter: Basic Concepts
Topic 1
Pure substance or a mixture?
A mixture is a combination of two or more substances in which the basic identity of each
substance is not changed.
Unlike pure substances, mixtures do not have specific compositions.

2. Pure substance or a mixture?
Chemistry and Matter: Basic Concepts
Topic 1
Pure substance or a mixture?
A physical change is a change in matter that does not involve a change in the chemical identity of individual substances.
Examples of physical changes include:
boiling,
evaporating,
freezing,
dissolving,
melting,
and crystallizing.

3. Pure substance or a mixture?
Chemistry and Matter: Basic Concepts
Topic 1
Pure substance or a mixture?
Physical properties are characteristics that a sample of matter exhibits without any change in its identity.

4. Pure substance or a mixture?
Chemistry and Matter: Basic Concepts
Topic 1
Pure substance or a mixture?
Examples of the physical properties of a chunk of matter include its:
solubility,
melting point,
boiling point,
color,
density,
electrical conductivity,
and physical state (solid, liquid, or gas).

5. Pure substance or a mixture?
Chemistry and Matter: Basic Concepts
Topic 1
Pure substance or a mixture?
Homogeneous mixtures are the same throughout.
Another name for a homogeneous mixture is solution.
Some solutions are gases. Air, for example, is a homogeneous mixture of several gases.
Some solutions are solid.
Liquid solutions do not have to be liquid or contain water.

6. Pure substance or a mixture?
Chemistry and Matter: Basic Concepts
Topic 1
Pure substance or a mixture?
When you dissolve sugar in water, sugar is the solute—the substance being dissolved.
The substance that dissolves the solute, in this case water, is the solvent.
When the solvent is water, the solution is called an aqueous solution.

7. Pure substance or a mixture?
Chemistry and Matter: Basic Concepts
Topic 1
Pure substance or a mixture?
Many of the solutions you encounter are aqueous solutions, for example, soda, tea, contact-lens cleaner, and other clear cleaning liquids.
In addition, most of the processes of life occur in aqueous solutions.

8. Pure substance or a mixture?
Chemistry and Matter: Basic Concepts
Topic 1
Pure substance or a mixture?

9. Two Types of Substances
Chemistry and Matter: Basic Concepts
Topic 1
Two Types of Substances
One type of pure substance can be broken down into simpler substances. This type of substance is called a compound.
Another type of substance cannot be broken down into simpler substances. Such a substance is called an element.
All the substances of the universe are either elements, compounds formed from elements, or mixtures of elements and compounds.

10. Two Types of Substances
Chemistry and Matter: Basic Concepts
Topic 1
Two Types of Substances
Of the known elements, only about 90 occur naturally on Earth. The remainder are synthesized, usually in barely detectable amounts, in high-energy nuclear experiments.
Less than half of the 90 naturally occurring elements are abundant enough to play a significant role in the chemistry of everyday stuff.

11. Compounds Are More Than One Element
Chemistry and Matter: Basic Concepts
Topic 1
Compounds Are More Than One Element
A more complete definition is that a compound is a chemical combination of two or more different elements joined together in a fixed proportion with a unique set of chemical and physical properties.
More than 10 million compounds are known and the number keeps growing.

12. Compounds Are More Than One Element
Chemistry and Matter: Basic Concepts
Topic 1
Compounds Are More Than One Element
Some new compounds are discovered and isolated from natural chemical sources such as plants and colonies of bacteria and are synthesized in laboratories for many different uses.

13. Compounds Are More Than One Element
Chemistry and Matter: Basic Concepts
Topic 1
Compounds Are More Than One Element
The properties of the compound are different from the properties of the elements that compose the compound.
silver bromine = silver bromide

14. Compounds Are More Than One Element
Chemistry and Matter: Basic Concepts
Topic 1
Compounds Are More Than One Element
A formula is a combination of the chemical symbols that show what elements make up a compound and the number of atoms of each element.
Compound
Formula
Caffeine
C8H10N4O2

15. Compounds Are More Than One Element
Chemistry and Matter: Basic Concepts
Topic 1
Compounds Are More Than One Element
Formulas provide a shorthand way of describing a submicroscopic view of a compound.
You probably already use formulas like H2O and CO2 as a way of talking about water and carbon dioxide.

16. Organizing the Elements
Chemistry and Matter: Basic Concepts
Topic 1
Organizing the Elements
The periodic table organizes elements in a way that provides a wealth of chemical information—much more than is evident to you now. It shows the chemical symbols for the elements.
Their symbols usually correspond to their names in Latin.

17. Periodic Table of the Elements
MODERN PERIODIC TABLE
Arranged in order of increasing atomic number
Rows are called periods
Columns are called groups or families
Periodic Law – elements arranged in increasing atomic number have a periodic pattern in their physical and chemical properties.
Elements with similar properties are in the same group.

18. Basic Assessment Questions
Topic 1
Question 1
Identify each of the following as either a compound or a mixture.
A. sand
B. water
C. juice

19. Answers A. sand mixture B. water compound C. juice mixture Topic 1
Basic Assessment Questions
Topic 1
Answers
A. sand
mixture
B. water
compound
C. juice
mixture

20. Basic Assessment Questions
Topic 1
Question 2
Classify each of the following as an intensive or extensive physical property.
A. density
B. mass
C. color
D. melting point
E. volume

21. Answers A. density intensive property B. mass extensive property
Basic Assessment Questions
Topic 1
Answers
A. density
intensive property
B. mass
extensive property
C. color
intensive property
D. melting point
intensive property
E. volume
extensive property