1. TOPIC II Describing matter

2. They are the fundamental building block of matter.
Atoms and Molecules
They are the fundamental building block of matter.
Matter is composed of tiny particles called atoms.
Atom: smallest part of an element that is still that element.
Molecule: Two or more atoms joined and acting as a unit.
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3. Iron (Fe), aluminum (Al), oxygen (O2), and hydrogen (H2)
Element
A substance that cannot be broken down into other substances by chemical methods.
Examples:
Iron (Fe), aluminum (Al), oxygen (O2), and hydrogen (H2)
All of the matter in the world around us contains elements.
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4. Elements
Which element is most abundant in both Earth’s crust and in the human body?

5. Elements
Symbols consists of one or two letters, with the first letter capitalized.
Often derived from the English name.
You will need to know these symbols and to learn others.

6. Introduction to the Periodic Table
The vertical columns of the periodic table are called groups, or families.
Each group contains elements with similar chemical properties.
The horizontal rows of elements in the periodic table are called periods.
Physical and chemical properties change somewhat regularly across a period.

8. Types of Elements Metals
A metal is an element that is a good electrical conductor and a good heat conductor.
Properties of metals
most are solids at room temperature
malleable - they can be hammered or rolled into thin sheets
ductile - they can be drawn into a fine wire
conduct electricity and heat well

9. Types of Elements
Gold, copper, and aluminum are metals

10. Properties of nonmetals many are gases solids are brittle
Types of Elements
Nonmetals
A nonmetal is an element that is a poor conductor of heat and electricity.
Properties of nonmetals
many are gases
solids are brittle
poor conductors of heat and electricity

11. Types of Elements
Various nonmetal elements
(a) carbon, (b) sulfur, (c) phosphorus, and (d) iodine

12. Types of Elements
Metalloids
A metalloid is an element that has some characteristics of metals and some characteristics of nonmetals.
Properties of metalloids
all metalloids are solids at room temperature.
semiconductors of electricity.

13. He Types of Elements Noble Gases
elements in Group 18 of the periodic table
generally unreactive
gases at room temperature He

14. Water (H2O), carbon dioxide (CO2), table sugar (C12H22O11)
Compound
A substance composed of a given combination of elements that can be broken down into those elements by chemical methods.
Examples:
Water (H2O), carbon dioxide (CO2), table sugar (C12H22O11)
A compound always contains atoms of different elements.
A compound always has the same composition (same combination of atoms).
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15. How many of the following are compounds? H2O, N2, NaOH, MnO2, H2
Concept Check
How many of the following are compounds?
H2O, N2, NaOH, MnO2, H2
Three – H2O, NaOH, MnO2
Five – All of the substances are compounds. Compounds always contain atoms of different elements.
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16. Always have the same composition and are formed by chemical processes.
Pure Substances
Always have the same composition and
are formed by chemical processes.
Either elements or compounds.
Examples:
Pure water (H2O), carbon dioxide (CO2), hydrogen (H2), gold (Au)
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17. Have variable composition. Examples Wood, wine, coffee, granite
Mixtures
Have variable composition.
Examples
Wood, wine, coffee, granite
Can be separated into pure substances: elements and/or compounds using physical processes.

18. Having visibly indistinguishable parts. A solution.
Homogeneous Mixture
Same throughout.
Having visibly indistinguishable parts.
A solution.
Does not vary in composition from one region to another.
Apple Juice Cranberry Juice Orange Juice

19. Homogeneous Mixture – Examples
Air around you
Brass
Table salt stirred into water

20. Heterogeneous Mixture
Having visibly distinguishable parts.
Contains regions that have different properties from those of other regions.

21. Heterogeneous Mixture – Examples
Oil and vinegar dressing
Sand stirred into water
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22. Classification of Matter

23. Pure water Gasoline Jar of jelly beans Soil Copper metal Concept Check
Which of the following is a homogeneous mixture?
Pure water
Gasoline
Jar of jelly beans
Soil
Copper metal
gasoline
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24. Oxygen and Helium in a SCUBA tank ____
Classify as Pure Substance (PS), Homogeneous (HO) or Heterogeneous Mixture (HE)
Oxygen and Helium in a SCUBA tank ____
Oil and vinegar salad dressing ____
Table salt (NaCl)____
Maple Syrup____
Pure water____
Gasoline____
Jar of jelly beans____
Soil____
Copper metal____
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