1. Preview Section 1 Elements Section 2 Compounds Section 3 Mixtures
Elements, Compounds, and Mixtures
Preview
Section 1 Elements
Section 2 Compounds
Section 3 Mixtures
Concept Mapping

2. Objectives Describe pure substances.
Section 1 Elements
Objectives
Describe pure substances.
Describe the characteristics of elements; give examples.
Explain how elements can be identified.
Classify elements according to their properties.

3. Elements, the Simplest Substances
Section 1 Elements
Elements, the Simplest Substances
Element: pure substance that cannot be separated into simpler substances by physical or chemical means.

4. pure substance: substance in which there is only one type of atom

5. Properties of Elements
Section 1 Elements
Properties of Elements
Each element can be identified by its unique set of properties.
An element may share property w/ another element, but other properties help distinguish elements from each other.
Elements can be identified by using physical properties and chemical properties.

6. Identification of Elements
Physical Properties
Chemical Properties
Melting point
Boiling point
Density
Colour
Hardness
Texture
Solubility in water
Magnetic
Flammability
Reactivity with oxygen
Reactivity with acid

7. Classifying Elements by Their Properties, ctd
Section 1 Elements
Classifying Elements by Their Properties, ctd
Categories Are Similar
By knowing category to which unfamiliar element belongs  can predict some of its properties.
The next slide show examples and properties of metals, nonmetals, and metalloids.

8. Classifying Elements by Their Properties
Section 1 Elements
Classifying Elements by Their Properties
Three Major Categories of Elements:
METALS
NONMETALS
METALLOIDS
shiny
good conductor of heat and electricity
malleable
ductile
dull (not shiny)
poor conductor
brittle solids
nonmalleable
semiconductors (somewhat conduct heat, electricity)
some shiny; some dull
somewhat malleable
somewhat ductile

9. Section 1 Elements

10. Bellringer The word compound refers to something that
Section 2 Compounds
Bellringer
The word compound refers to something that
consists of two or more parts. How might you make
a compound using elements? How many compounds
can you think of that you use every day.
Record your answers in your science journal.

11. Objectives Explain how elements make up compounds.
Section 2 Compounds
Objectives
Explain how elements make up compounds.
Describe the properties of compounds.
Explain how a compound can be broken down into its elements.
Give examples of common compounds.

12. Compounds: Made of Elements
Section 2 Compounds
Compounds: Made of Elements
Compound: pure substance composed of two or more elements that are chemically combined. [Elements combine by reacting with one another.]
Molecule: particle of a compound, formed when atoms of two or more elements join together.

13. Compounds: Made of Elements
Section 2 Compounds
Compounds: Made of Elements
The Ratio of Elements in a Compound
Elements join in a specific ratio according to their masses to form a compound.
EX: every sample of water has a 1:8 mass ratio of hydrogen and oxygen.

14. Properties of Compounds
Section 2 Compounds
Properties of Compounds
Each compound can be identified by its physical and chemical properties.
Properties: Compounds Versus Elements
A compound has properties that differ from those of the elements that form it.
EX: sodium chloride
sodium (soft, silvery metal, reacts violently w/water
+ chlorine (poisonous greenish gas)
= sodium chloride (white, crystalline solid, safe to eat)

15. Breaking Down Compounds
Section 2 Compounds
Breaking Down Compounds
Compounds can be broken down into their elements or into simpler compounds by chemical changes.
Methods of Breaking Down Compounds
Sometimes, energy is needed for a chemical change to happen.
2 ways to add energy:
apply heat
apply electric current

16. Compounds in Your World
Section 2 Compounds
Compounds in Your World
Cpds in Nature EX: proteins, carbon dioxide, carbohydrates.
Compounds in Industry
Some cpds must be broken down for industrial use.
Other cpds made in industry for use as medicines, food preservatives, synthetic fabrics.

17. Bellringer When you add sugar to coffee, tea, iced tea, or
Section 3 Mixtures
Bellringer
When you add sugar to coffee, tea, iced tea, or
lemonade, the sugar disappears. What do you think
happens to the sugar? Does the same thing happen
to salt when you add it to soup? Does temperature,
acidity, or color matter? Why or why not?
Record your answers in your science journal.

18. Objectives Describe three properties of mixtures.
Section 3 Mixtures
Objectives
Describe three properties of mixtures.
Describe four methods of separating parts of a mixture.
Analyze a solution in terms of its solute and solvent.
Explain how concentration affects a solution.
Describe the particles in a suspension.
Explain how a colloid differs from a solution and a suspension.

19. Properties of Mixtures
Section 3 Mixtures
Properties of Mixtures
mixture: combination of two or more substances that are NOT chemically combined.
No Chemical Changes in a Mixture
No chemical changes happen when a mixture is made.
Each substance has the same chemical makeup it had before the mixture was formed.

20. Properties of Mixtures, ctd
Section 3 Mixtures
Properties of Mixtures, ctd
Separating Mixtures Through Physical Methods Mixtures can be separated by using physical changes. Physical changes do not change the identities of the substances.
The next slide shows some common ways to separate mixtures by using physical changes.

21. Section 3 Mixtures

22. Properties of Mixtures, ctd
Section 3 Mixtures
Properties of Mixtures, ctd
The Ratio of Components in a Mixture
The components of a mixture do NOT need to be mixed in a definite ratio.
EX: granite is mixture of three minerals.
Different ratios of the minerals give granite different colors, but the mixture is always called granite.

23. Solutions solution: a mixture that appears to be a single substance.
Section 3 Mixtures
Solutions
solution: a mixture that appears to be a single substance.
dissolving: process in which particles of substances separate and spread evenly throughout a mixture
solute: the substance that is dissolved.
solvent: the substance in which the solute is dissolved.

24. Solutions, ctd Examples of Solutions
Section 3 Mixtures
Solutions, ctd
Examples of Solutions
Liquid solutions: soft drinks, gasoline, and tap water.
Gaseous solutions: air.
Solid solutions: steel, metal alloys such as brass Alloys: solid solutions of metals or nonmetals dissolved in metals.

25. Section 3 Mixtures
Solutions, ctd
Particles in Solutions  are so small that they never settle out; they also cannot be removed by filtering.
The particles in solutions are so small they don’t even scatter light.

26. Concentrations of Solutions
Section 3 Mixtures
Concentrations of Solutions
concentration: measure of the amount of solute dissolved in a solvent
Concentrated or Dilute?
Solutions can be described as being concentrated or dilute.
But these two terms DO NOT tell the amount of solute that is dissolved.
The next slide shows how to calculate concentration.

27. Concentrations of Solutions, ctd
Section 3 Mixtures
Concentrations of Solutions, ctd
Solubility: ability of a solute to dissolve in a solvent at a certain temperature.
The solubility of most solids in water increases with temperature.

28. Concentrations of Solutions, ctd
Section 3 Mixtures
Concentrations of Solutions, ctd
Dissolving Gases in Liquids
Gases become LESS soluble in liquids as temperature increases.
Dissolving Solids Faster in Liquids
Three ways to make a solute dissolve faster:
mixing the solution
heating the solution
crushing the solute into smaller particles (increase surface area).

29. Section 3 Mixtures
Suspensions
suspension: mixture in which particles of a material are dispersed throughout a liquid or a gas but are large enough that they settle out.
The particles in a suspension are large enough to scatter or block light.
A suspension can be separated by passing it through a filter.

30. Section 3 Mixtures
Colloids
colloid: mixture in which the particles are dispersed throughout but are not heavy enough to settle out.
Particles in a colloid are large enough to scatter light.
A colloid cannot be separated by passing it through a filter.