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Matter in Our World
Matter
Made up of atoms
Atoms that are all the same make an
element
Every element has different types of atoms
Kinetic Theory
Three main points
All matter is made of atoms and molecules
These atoms and molecules are always in
motion
At high temperatures, particles move faster
At the same temperature, larger atoms and
molecules move slower than smaller ones
Kinetic Theory
Used to describe the states of matter
Solid
Liquid
Gas
Changing States
Solid
Atoms move very, very slowly
Set volume
Set shape
States of
Matter
Liquid
Atoms move around
Set volume
Changing shape
Can look at viscosity
High viscosity = less flowing
States of
Matter
Gas
Atoms move very, very fast
Changing volume
Changing shape
Exerts pressure on objects
High pressure = lots of movement
States of
Matter
Changing States of Matter
Energy makes
this happen
Red
Energy added
Blue
Energy taken
away
Changing States of Matter
Total amount of matter never changes
Law of conservation of mass
Total amount of energy never changes
Law of conservation of energy
Changes in Matter
Chemical change
Changes the make-up of matter
Different matter is made
Physical change
Does not change the make-up of matter
Same matter exists – just a different form
Clues to Chemical Change
Change in color
Production of gas
Production of a solid
Key words:
Burn, decay, ‘die’, ripen, rot
Clues to Physical Change
Key words
Cut, tear, melt, freeze, dissolve, grind
Idea of the Atom
Democritus (BC)
Had the original idea that all matter was made
of a small ‘invisible’ units
Called these atoms
Dalton (1800’s)
Proposed his theory of matter and the atom
Widely accepted because of his evidence
Dalton’s Atomic Theory
Every element is made of tiny, unique
particles that cannot be divided
Atoms of the same element are exactly
alike
Atoms of different elements can join to
form molecules
Elements
Element
Symbol
Hydrogen
H
Mg
Oxygen
O
Br
Sodium
Na
Nitrogen
K
Sulfur
Iodine
Element
I
C
Symbol
Ca
Boron
Chlorine
Iron
Zn
Si
Ag
Neon
Current Atomic Model
Atoms can be divided
Protons
Positive charged
Electrons
Negative charged
Neutrons
No charge
Call these subatomic particles
Current Atomic Model
Electrons
are around
the nucleus
Nucleus
Has protons
and neutrons
in it
Number of Protons = Number of Electrons
Tells us the atom is neutral (no charge)
Describing the Atom
Mass Number
Number of protons added to the number of
neutrons
protons
neutrons
9 + 9 = 18
Mass Number
Also known as the Atomic Mass
Can be found on the periodic table
Describing the Atom
Atomic Number
Number of protons in the atom
Found on the periodic table
Critical Thinking
If Dalton were still alive, he might argue:
“Atoms are neutral so they can’t be made
of charged particles.” Explain why this is
not true.
Periodic Table
Periods
Groups
Divisions of the Periodic Table
Metals
Good conductors of electricity
Mostly found on the left side of the table
Usually solids
Some are shiny (middle ones)
Some are very reactive (one on far left)
Non Metals
Cannot conduct electricity
Most are on the right side of the table
Exception = hydrogen
Can be solids, liquids or gases
Can be extremely reactive (group 17)
Can not react at all (group 18)
One very important nonmetal
A part of every living organism = Carbon
Matter and Atoms
When elements chemically combine they
form compounds
The same element can combine
Different elements can combine
Matter can be physically combined into
mixtures
Lots of elements in the same place
Lots of compounds in the same place
Combination of elements and compounds in the
same place
Matter and Atoms
Elements, compounds, and molecules are
all pure substances
Matter also exists as mixtures
Homogenous
Mixtures that look the same throughout
Substances are miscible
Heterogeneous
Mixtures that you can see the different substances in
Substances are immiscible
Matter
Chemical formulas are important for telling
us what compounds are made of
Sugar – C12H22O11
Carbon
Hydrogen
Oxygen
12 atoms
22 atoms
11 atoms
Common Compounds
 Salt = NaCl
 Ammonia = NH3
 Baking Soda = NaHCO3
 Water = H2O
 Hydrogen Peroxide = H2O2
 Bleach = NaOCl
 Glass = SiO2
 Vinegar = CH3COOH
Acids
A substance that forms H3O+ (hydronium
ions) when dissolved in water
Adds a H to water
Properties
Sour taste
Conduct electricity
Reacts with metals
Strong Acids vs. Weak Acids
Strong
All acid compounds completely dissolve in
water
Lots of H3O+
Weak
Not all acid compounds are dissolved in water
Not many H3O+
Bases
A substance that forms OH- (hydroxide
ions) when dissolved in water
Takes a H away from water
Properties
Bitter taste
Conduct electricity
Feels slippery
Strong Base vs. Weak Base
Strong
Reacts with water to form lots of OH-
Weak
Forms very few OH- when it reacts with water
Detecting Acids and Bases
 Use an indicator
 A substance that turns color when touched by an acid or base
 Litmus paper - red and blue types
 Acids
 A blue indicator will turn red when in acid
 Bases
 A red indicator will turn blue when in base
Litmus Paper Tests
pH Scale
Used to determine how acidic or basic
something is
Measures the concentration of H3O+
Ranges from 0 to 14
7 is neutral
Below 7 is acidic
Above 7 is basic
pH Paper Test
Lab Data Table
Solution
Blue Litmus Red Litmus
pH Paper
A or B
pH Scale
Neutralization
A reaction between acids and bases
The hydronium (H3O+) ions reaction with the
hydroxide (OH-) ions
Form water and salt
HCl + NaOH → NaCl + H2O
Acid
Base
Salt
Water