1. Chapter 7 Foundations of Chemistry

2. Essential Questions What is a substance?
How do atoms of different elements differ?
How do mixtures differ from substances?
How can you classify matter?
What are some physical properties of matter?
How are physical properties used to separate mixtures?
How can a change in energy affect the sate of matter?
What happens when something dissolves?
What is meant by conservation of mass?
What is a chemical property?
What are some signs of chemical change?
Why are chemical equations useful?
What are some factors that affect the rate of chemical reactions?

3. What do you already know?
Move to the “true” or “false” side of the room based on your beliefs about the following statements
TRUE
FALSE
The atoms in all objects are the same
When wood burns, new materials form
The weight of a material never changes, regardless of where it is
You cannot always tell by an object’s appearance whether it is made of more than one type of atom
When you stir sugar into water, the sugar and water evenly mix
Boiling is one method used to separate parts of a mixture
Temperature can affect the rate at which chemical changes occur

4. Matter
___Matter____- Anything that has mass and takes up space.
Everything in the universe that you can see is made up of matter.
Is it matter?
Toaster ____
Bowl of soup____
Steam____
Sound____
Dust____
Air____
Heat____
Flag____
Bacteria____
Light____

5. 1-Classifying matter
A ______________ is matter with composition that is always the same
Ex: Aluminum, water, oxygen, sugar
Two major types of substances
____________ are substances that consist of just one type of atom
Elements are arranged in the periodic table
substance
Elements

6. 1-Classifying matter
A substance is matter with composition that is always the same
_____________ are substances containing atoms of two or more different elements chemically bonded together
Atoms are always combined in the same way
Compounds are represented by chemical formulas
H and O are atom symbols
2 (subscript) tells you how many
Compounds

7. 1-Classifying matter Properties Compounds versus Elements
A compound will have __________________ than the elements that make it up
Different properties

8. 1-Classifying matter What is a mixture?
A _mixture___ is matter that can vary in composition
No chemical reaction
No compound formed
Each substance keeps its original _identity__
_No Fixed Ratio__— not always the same

9. 1-Classifying matter Heterogeneous Homogeneous not evenly evenly
_______________________ Mixture
______________________ Mixture
Definition: type of mixture in which the individual substances are _________________ mixed
Definition: type of mixture in which the individual substance are ____________ mixed
Different samples of a given heterogeneous mixture can have different combinations of the same substance
Different samples of a given homogeneous mixture will have the same combinations of the same substances
Heterogeneous
Homogeneous
not evenly
evenly

10. 1-Classifying matter
Homogeneous mixtures are also known as _______________
Solutes dissolve into solvents
Dissolving means to form a solution by mixing ___________
solutions
evenly

11. 1-Classifying matter Comparing Mixtures and Compounds elements both
Made up of elements, compounds, or ________
Made of _____________
_________________ in original properties of components
_____________ in original properties of components
Separated by ___________means
Separated by ___________ means
Formed using ____ ratio of components
Formed using a _____ ratio of components
elements
both
No change
Change
chemical
physical
any
set

12. 1-Classifying matter

13. 2- Physical Properties
A _physical property__of matter can be observed or measured without changing the matter’s __identity_____.
Examples:
__color____
Melting and boiling points
___mass____
Conduct electricity
Strength
Flexibility
State – __solid, liquid, gas__
Density – the amount of mass in a given volume
_solubility___
Ductility – ability to be draw into wires
Malleability – ability to be hammered into sheets

14. 2- Physical Properties _Viscosity__ - A liquid’s resistance to flow
_Malleability__– Can be hammered into thin sheets

15. 2-Physical Properties Size-dependent properties
These are properties of matter that depend on the size or amount of matter
Examples: mass and volume
Size-independent properties
These are properties of matter that do not depend on the amount of matter present
Examples: melting point, boiling point, electrical and thermal conductivity, solubility, and density

16. 2- Physical Properties Mass & Weight
Mass– the amount of matter in an object.
The more matter in the object, the greater the mass
Mass of an object is the same regardless of the object’s location in the universe.
Mass vs. Weight
Mass and weight do NOT have the same meaning.
Weight– the measure of gravitational force exerted on an object.
Will change with location in the universe

17. Difference Between Mass and Weight
Measure of the amount of matter in an object
Always the same regardless of location in universe
Measured using a balance
Expressed in grams
WEIGHT
Measure of gravitational force on an object
Changes based on location in the universe
Measured using a scale
Expressed in Newtons (N)

18. Density
Density is a physical property that describes the relationship between mass and volume.
Density- the amount of matter in a given space or volume.
Basketball vs. bowling ball.
They both are the same size, but the bowling ball has more mass.
Since it has more mass, it has a greater density

19. Density Continued Denser liquids go to the bottom of the container.
Think of vinegar and oil salad dressing
Density of solids.
Would you rather carry 1kg of feathers or 1kg of lead?
The lead would be much smaller to carry around.
An object will float on water if it is less dense than water
The object will sink if it is more dense than water.

20. Volume
Volume- The amount of space taken up, or occupied, by an object.
Because objects have volume, they cannot occupy the same space at the same time.

21. Liquid Volume Units for Liquid Volume Measuring Liquid Volume L mL cm3
Use graduated cylinder– more accurate
Meniscus – the curve at a liquids surface
Read liquid measurements from the bottom of the meniscus.

22. Volume of a regular shape
Regularly Shaped Objects
Units for solids
cm3 units (having 3 sides)
Volume = length (l) x width (w) x height (h)
Example: What is the volume of a block that measures:
Length: 3 cm Width: 5 cm Height: 7 cm

23. Volume of a regular shape
What is the volume of a box that has a length of 5 cm, a width of 1 cm, and a height of 2 cm?
What is the volume of a box that has a height of 10 cm, a width of 2 cm, and a length of 3 cm?

24. Volume of an irregular shape
Irregularly Shaped Objects
Same units as above
Use water displacement method.
Submerge object in a known amount of water and read the level change.
1 mL = 1 cm3
Ex. Graduated cylinder has 25.0 mL of water in it. After Tom places a paper clip in it, the water level rises to 28.6 mL. What is the paper clips volume?

25. Volume of an irregular shape
Initial Volume ___________
Final Volume ___________
Volume of object _________
Initial Volume ___________
Final Volume ___________
Volume of object _________

26. 2- Density
To find density, you must first measure the mass and volume of the object.
The formula is:
Density = mass D = m
volume V
The unit will be g/cm3 . You may also see kg/m3 or kg/L

27. 2- Density
What is the density of an object whose mass is 25g and whose volume is 10 cm3?
Suppose you have a lead ball whose mass is 454 g and density is g/cm3. What is the volume of the ball?

28. 2 - Density
What is the mass of a 15 mL sample of mercury with a density of g/mL?
A graduated cylinder contains 25 mL of water. When a 4.5 g paper clip is dropped into the water, the water level rises to 36 mL. What is the density of the paper clip?

29. 2-Density Combination problem:
You have a substance that has a mass of 96.6g. When you place it into a graduated cylinder, the water rises from 10 mL to 15 mL.
Find the volume of the substance
Find the density of the substance
You think it might be copper (density= 8.96 g/mL) or gold (density =19.32 g/mL). Which material is it?

30. 3- Physical Changes Physical changes do not form new substances.
A physical change is a change in size, shape, form, or state of matter in which the matter’s identity stays the same
Examples include:
silver shaped into jewelry
Cutting a piece of wood
Tearing a piece of paper
Dissolving sugar in water
Melting a popsicle

31. 3-Physical Changes States of matter
Solids have very little energy and vibrate in place
Liquids have a little more energy and slide back and forth
Gases have the most energy and fly all over the place

32. 3-Physical Changes Conservation of Mass
During a physical change, the physical properties of matter change, but the particles are the same as those present before the change occurred
The mass before a physical change has to be the same as the mass after a physical change

33. 4 - Chemical Properties & Changes
A chemical property is a characteristic of matter that can be observed as it changes to a different type of matter
Flammability – ability to burn
Reactivity is the ability of two or more substances to combine to form one or more new substances
Iron combines with water and oxygen to form rust.

34. 4-Chemical Properties and Changes
Physical versus Chemical properties
Physical Property
Chemical Property
Shape Bending an iron nail will change its shape
Reactivity An iron nail can react with oxygen in the air to form iron oxide (rust)
State Rubbing alcohol is a clear liquid at room temperature
Flammability Rubbing alcohol is able to burn easily

35. 4-Chemical Properties and Changes
A chemical change is a change in matter in which the substances that make up the matter change into other substances with new physical and chemical properties
When you bake a cake, you combine flour, sugar, eggs, and several other ingredients. The product is the cake. You cannot unbake the cake and return to the original ingredients.

36. Signs of a Chemical Change
Several signs indicate a chemical change has taken place. These include:
Change in color
Change in odor
production of heat
fizzing and foaming, or bubbling
or formation of a precipitate (solid)
When you bake a cake you smell it baking, you see it browning, and when you cut it open you can see pockets of gas.

37. Color Change
Copper will form a patina when exposed to moist air

38. Production of a Gas
Carbon Dioxide gas forms when baking soda is mixed with vinegar.

39. Formation of a Precipitate
Curds in cottage cheese form when acid is added to milk

40. 4-Chemical Properties and Changes
Physical versus Chemical Changes
DID THE CHEMICAL COMPOSITION CHANGE?
If yes, it’s chemical
If no, it’s physical
Change in texture Grinding baking soda into a fine, powdery substance is a physical change
Reactivity with Vinegar Gas bubbles are produced when vinegar is poured into baking soda