1 CHAPTER 2
Mar 26, 2015
1
CHAPTER 2
2
3
ELEMENTS: Periodic Table
____ total elements : ____ natural and ____ man-made
4
5
ORGANIZATION OF PERIODIC TABLE
6
ATOMIC STRUCTURE
7
THE NUCLEUS OF AN ATOM
How does an atom stay together?
ELECTRON ENERGY LEVELS
9
DIATOMIC ELEMENTS
• Elements that must exist naturally as 2 atoms bonded together (until it forms a chemical bond with any other element)
• Br I N Cl H O F
H2 N2 O2 F2 Cl2 Br2 I2
10
ISOTOPES
11
CHEMICAL BONDING
Bonding
12
+ =
Sodium is a silver-colored metal that reacts so violently with water that flames are produced when sodium gets wet. Chlorine is a greenish-colored gas that is so poisonous that it was used as a weapon in World War I. When chemically bonded together, these two dangerous substances form sodium chloride, a compound so safe that we eat it every day - common table salt!
13
Bohr Model Method:
Step 1: Draw the energy levels for each element
Step 2: Show the arrow of transfer. There should be an arrow showing transfer for EACH electron given away. (Just like the top picture)
Step 3: State the ions below each atomic structure to indicate that electrons have been gained or lost.
IONIC BOND:Bohr Method
14
IONIC BOND:Lewis Dot Structure
NaCl
MgO
Lewis Dot Method:
Step 1: Write the symbol for each atom separately and show valence electrons (evenly spread out )
Step 2: No arrows. Write ions once transfer has taken place. Show electrons for the ORIGINAL outer shell (the one that gained will show electrons).
Remember that ions are written as symbol with superscript.
REDOX REACTIONSReduction = gain electronsOxidation = lose electrons
16
COVALENT BOND:Bohr ModelBohr Model Method:
Step 1: Draw the energylevels for each element separately.
Step 2: Show the energy levels joined (similar to the top picture)
All diatomic elementsDemonstrate a Covalent bondRemember: BrINClHOF(Chlorine isshown to the right)
17
Mo
lecular fo
rmu
laCOVALENT BOND:Lewis Dot Structure
Lewis Dot:
Step 1: Draw the dot diagram for each element individually (use X and • for different atoms)
Step 2: Draw the dot diagram for the compound
Step 3: Show the molecular formula (including lone electrons)
18
STATES OF MATTER
Solid Liquid Gas• Definite shape Shape of container No definite shape• Definite volume Volume of container No def. volume• Tightly packed May overlap Very spread out• Vibrate in place Move faster Very fast
19
CHANGES IN STATE
2 types of Latent Heat = energy absorbed (stored) or released
Heat of fusion = energy released; Gas to Liquid to Solid
Heat of Vaporization = energy absorbed; Solid to Liquid to Gas
20
CHEMICAL EQUATIONS
Reactant
Reactant
Reactant
Reactant
Product
Product Product Product
Product
22
CHEMICAL REACTIONSEndothermic vs. Exothermic
Exothermic– energy released – reactants have more energy than products
Endothermic – energy absorbed – products have
more energy than reactants
23
SECTION 3WATER AND SOLUTONS
bRONZE
brass
24
3 unique
characteristics of water
25
POLARITYOF
WATER
26
HYDROGEN BONDING(Weak Bond)
Surface Tension is caused by…
27
28
COHESION / ADHESION / CAPILLARITYCohesion attracts molecules of the same kind (water to water)Adhesion attracts molecules of different kinds (tape and hair)
Capillarity is the attraction of molecules allowing a liquid to rise
29
SOLUTIONS
bRONZE
brass
30
THE DISSOCIATION OF WATER
Step 1: One water molecule bumps into another water molecule
Step 2: One of the water molecules dissociates (comes apart). When water dissociates, hydroxide ions (OH-) and a hydrogen ion (H+) are produced.
31
ACIDS / BASESAcidity / Alkalinity depends on the amount of hydronium
atoms.
HCl + NaOH NaCl + H2O
(Acid) (Base)---(Salt) (Water)
If more hydroxide than hydrogen= BASE
If hydrogen= hydroxide =
NEUTRAL
If more hydrogen than hydroxide = ACID
32
TESTING FOR ACIDS / BASES