1. Foundations of Chemistry
Chapter 7
Physical Science

2. Bell Work Ch7 L.1 Matter: anything that has mass and takes up space.
Atom: a small particle that is a building block of matter.
Substance: matter with a composition that is always the same.
Element: a substance that consists of just one type of atom.
Compound: a type of a substance containing atoms of two or more different elements chemically bonded together.
Mixture: matter that can vary in composition.
Heterogenous mixture: a type of mixture in which the individual substances are not evenly mixed.
Homogeneous mixture:a type of mixture in which individual substances are evenly mixed.
Dissolve: to form a solution by mixing evenly.

3. Matter Look around- what makes up objects around you?
Things can be made up of different kinds of matter.
What about things you can’t see?
Air?
Does it have mass? Does it take up space?
IF YES TO BOTH= matter.
Air= yes
Sound= no
Light= no

4. Atom Small particle that is the building block of matter
Diameter of hair is 1,000,000x bigger than diameter of an atom
Structure of an atom
Nucleus (in center of atom)
Protons***
Have a positive charge
Atomic number= number of protons that determines properties of atom
Neutrons
Have a neutral charge
Electrons (floating around nucleus in electron cloud)
Have a negative charge
The size of an atom is roughly 10,000x wider than its nucleus.

5. Substances Matter with a composition that is always the same
Substance is always made of the same combination(s) of atoms
Examples: oxygen, aluminum, sugar, water
Two kinds of substances
Elements
Compounds

6. Elements A substance that is made up of only one kind of atom
Periodic table of elements
About 115 kinds of elements (115 kinds of atoms)
Each kind of atom has a different number of PROTONS
Aluminum has 13, Oxygen has 8
An Atom with 13 protons is always aluminum. An atom with 8 protons is always oxygen.
Substances can exist individually (Al) or in groups (O2)

7. Compounds
A type of substance containing atoms of two or more different elements chemically bonded together.
Example: CO2
One atom of carbon and two atoms of oxygen
Carbon dioxide is a compound because it is always formed the same way
Compounds often have different properties from the individual elements that compose it

8. Chemical formula
The combination of symbols and numbers that represents a compound
Show the different atoms in that make up a compound using the element symbols
Example: H2O
Two hydrogen atoms are bound to one oxygen atom

9. Mixtures Matter that can vary in composition
Combinations of two or more substances that are physically blended together
DO NOT combine chemically
They can be separated- filtering
Two kinds of mixtures
heterogeneous
homogeneous

10. Heterogeneous mixtures
A mixture in which individual substances are not mixed evenly
Two samples of the same mixture can have different concentrations of the substances
Examples: two buckets of sand/water taken from the beach

11. Homogeneous mixture
A mixture in which the individual substances are evenly mixed
Two samples from a solution will have the same amounts of each substance
Also known as a solution
Solvent: what is present in the largest amount, what is doing the dissolving
Solute: what is present in a smaller amount, what is being dissolved
Examples: Apple juice, air or salt water

12. Compounds vs Solutions
Water is a compound so it does not vary
Composition is ALWAYS the same
H2O is always H2O no matter how much you have
H is chemically bound to O
Salt water is a solution
NaCl (salt) and H2O (water) are mixed together but NOT chemically bound
Can add more salt to change relative amounts of salt relative to water= COMPOSITION CAN VARY
Can’t use chemical formula to describe

13. Homework Ch7 L.1
p.237 #1-11
Study for Quiz

14. Bell work Ch7 L.2
Physical properties: characteristic of matter that you can observe or measure without changing the identify of the matter
Mass: the amount of matter in an object
Density: mass per unit volume of a substance
Solubility: ability of one substance to dissolve in another

15. Physical properties The arrangement of atoms determines its properties
Each element and compound has a unique set of properties
How they look, how they react etc.

16. States of matter ALL atoms that make up matter are constantly moving
Solid
particles packed close together, not a lot of motion
Liquid
More motion than a solid. Particles still can touch but they move around relative to one another
Gas
Most motion of all three states. Particles move very quickly and spread out to fill their container

17. Size dependent properties
Mass: The amount of matter in an object
The larger the object the more mass it is
Value depends on the size of the object
NOT THE SAME AS WEIGHT (weight changes with location but mass does not)
Weight depends on gravity
Volume: Amount of space something takes up
Often measured in mL (milliliters)

18. Size independent properties
Melting point: the point at which a substance changes from solid to liquid
Boiling point: the point at which a substance changes from liquid to gas

19. Size independent properties cont’
Density: mass per unit volume of a substance
Conductivity:
Electrical- ability to conduct or carry an electrical current
Thermal- ability to conduct thermal energy
Solubility: ability of one substance to dissolve in another

20. Separating mixtures Use physical properties
things with a lower boiling point will boil off faster
CANNOT use physical properties to separate a compound into its elements

21. Homework Ch7 L.2
p. 246 #1-9
Study for quiz

22. Bel work Ch7 L.3
Physical change: a change in size, shape, form, or state of matter in which the matter’s identity stays the same

23. Physical changes
Does NOT become something different even though physical properties change
Identity stays the same

24. Change in shape and size
Can break things into smaller pieces or fold things into different shapes but doesn’t change the identity of the material

25. Change in state of matter
To change the state, the movement of particles has to change (slower or faster)
Adding thermal energy
Think of this as adding heat
Particles move faster until overcome bonds holding them together
The more energy added, the faster the particles move
Can change from solid to liquid (melting) to gas (vaporization)
Sublimation= change directly from solid to gas

26. Change in state of matter cont’d
Removing thermal energy
Think of this as removing heat
Particles move slower
The more energy removed, the slower the particles move
Can change from gas to liquid (condensation) to solid (freezing)
Deposition= change directly from gas to solid
Freezing/Melting are reverse properties and occur at the same temperature
same for boiling/condensation

27. Dissolving
Mixing evenly of substances whose identities do NOT change

28. Conservation of mass
During a physical change even though physical properties can change, the mass does not change

29. Homework Ch7 L.3
p.253 #1-7
Study for quiz

30. Bellwork Ch7 L.4
Chemical property: is a characteristic of matter that can be observed as it changes to a different type of matter
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
Concentration: is the amount of a substance in a certain volume

31. Chemical properties
Observe only when matter is changing identity (different than physical property)

32. Signs of chemical changes
How do you know if a chemical change has happened? Some hints:
bubbles
energy change
odor change
color change
These do not automatically mean a chemical change happened, ONLY if a new substance was formed.

33. Chemical reactions Particles can move and collide with one another
If they hit each other with enough force they can break apart and then can form new bonds and new combinations
New substances can form

34. Chemical formulas
Chemical equation: shows the chemical formulas of each substance in a reaction
Formulas to the left of the arrow represent the reactants
present before the reaction takes place
Formulas to the right of the arrow represent the products
new substances present after the reaction takes place

35. Balancing chemical equations
Remember that mass is conserved
The same number of atoms from each element should be on the left side and right side of the arrow
C3H8 + O2 → H2O + 3CO2
Is this balanced?
If not, how can we balance it?

36. Rate of chemical reactions
Particles move and collide with each other- the faster this happens the more the rate of a chemical reaction increases.

37. Rate of chemical reactions cont’d
Things that affect rate of chemical reactions
Higher temperature= particles move faster
Concentration= more particles available to bump into each other
Surface area= affects reaction if one reactant is solid. More space for reactants to collide.

38. Homework Ch7 L.4 p.261 #1-10 Study for quiz Extra credit: Test prep:
Outline all of chapter 7
Test prep: p