Transcript Chapter 4

Do Now
• Do you remember anything about atoms?
– Make an atom of carbon using play-dough
– Include the #
• protons,
• neutrons
• and electrons!
• WORK AS A TABLE
6
Carbon
Chapter 4
The Chemical Basis of Life
Lesson Objectives
• Identify the most common elements in
living things
• Recognize: Elements Vs Compounds
• Review the structure of atoms
7 Slides (Wordy.. Take NOTES)
Section 4.1
Life Requires about 25 Chemical Elements
• Everything is made up of matter
• What is matter?
• Regardless of the form of matter, it is composed of
elements
• What are elements? Your basic “ingredients”
• About 25 elements are essential to life
– Oxygen, Carbon, Hydrogen, Nitrogen make up 96% of all
living matter in your body
– “trace elements” = .01% but critical still are Iodine, Iron,
Copper, Fluorine, Manganese, and Selenium.
Compounds
• More complex types of matter
– 2+ elements that are chemically combined in a fixed ratio
• 1:2 or 2:1 or 1:4 (CO2, H20, CH4)
– QUESTION: if you have 2 carbon dioxide compounds, how
many carbons and oxygens do you have?
• 2 Carbons and 4 Oxygens 2(CO2)
• A compounds properties may differ greatly from those of its
component elements
– Example: page 73
• Table salt (NaCl) Na (metalic) Cl (gas)
• Water (H20) H (gas) O (gas)
• Most compounds are more complex
with 4+ elements
Section 4.2
Chemical Properties & Atomic Structures
• Different elements have different
properties
– Different phases at different temps
– Reactions with each other (Sodium and Water)
– Structures
How are an element’s properties related to its
structure?
Atoms
• Each element consists of a single kind of atom
that is different from the atoms of all the other
elements…
– Carbon element = carbon atoms
– Oxygen element = oxygen atoms
• Carbon atom is the smallest possible ‘piece’ of
the element carbon
• But an atom is NOT the smallest component…
Parts of the Atom
• “Subatomic” particles protons, neutrons, electrons
Positive
+
– Proton: _________
electrical charge (?)
Negative
– Electron: _________
electrical charge (?)
Neutral
– Neutron: _________
charge
• An elements physical & chemical properties
depend on the number and arrangement of its
subatomic particles
Parts of the Atom
Protons
• Nucleus contains the ________
and
Neutrons
__________,
tightly packed
– Electrons (less mass) continually move
around the outside of the nucleus; very fast
– Electric attraction b/w protons and electrons
keep the electrons from ‘flying’ away.
(gravitational pull)
• IMPORTANT “cloud” of electrons (pg 75) is not
really there.. Path of e- is very hard to trace
Differences in Elements
• Atomic Number all atoms of a
particular element have the same number of
protons which is called the atomic number.
– Ex: Helium = 2
b/c it has 2 protons
Word Associations!
Write any word you remember from today’s
lesson!
Now.. Choose any 5 and explain what you
learned about them in today’s lesson
Do Now 
If you have 4 water molecules
how many hydrogen atoms
and oxygen atoms are there
total?
H
H
H
H
Isotopes
• Isotope Same number of protons but different
number of neutrons
– Carbon 12 99% stable
– Carbon 13 13 neutrons stable
– Carbon 1414 neutrons (unstable/radioactive)
• All carbon has 6 protons, if it didn’t it wouldn’t be carbon
• Radioactive isotopes nucleus decays over time, gives
off radiation in the form of matter and energy…many
uses for them
Energy (NRG) Levels
Remember
• The first or lowest energy level (closest to the
nucleus) can hold 2 electrons (e-)
How tightly
electrons
are held by the protons
– Second
can hold
8 ein the nucleus
– Third can hold 18
and
• ChemicallyThe
reactive
if the
energy level
amount
of energy
they isn’t
have
completely
filled atoms react with one another…
Affect how
ENERGY
LEVELS!!
• Inert if the energy
levels are
filled (stable)
Energy Levels
Carbon Energy Levels
Carbon = 6 electrons
3
4
2
1
6
5
Atomic # = number of protons = # electrons
Periodic Table Coloring!
Green
Atomic
Number
1
H
Orange
Atomic
Yellow
Symbol
Electron
Blue
1st energy level
Red
1 p+
1n
Nucleus
Purple
Hydrogen
Label!!
Nucleus
Chapter Re-Cap (4.1-4.2)
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What is matter?
What is an element?
What is a compound (fixed ratio?)
What are 3 subatomic particles and their charges?
What prevents electrons from “flying away?”
What is an isotope? (Example)
Describe the first 3 energy levels.
4.3 Chemical Bonds
• Reactions (rxn) between atoms result in filled outer
NRG levels
– Reactions can be transferring e- or sharing them
between atoms
• Creates an attraction (chemical bond) holds them together
– 2 types of Chemical Bonds
• ionic
• covalent bonds!
Ionic Bonds!
• Occurs when an atom transfers an e- from
another atom
• Happens if the outer most layer is not filled
• Atoms “want” to be “complete”…this happens
when their shells are filled
– First layer has 2e- , Second has 8e• Attraction b/w atoms that are incomplete  to try and steal
those e- to make itself complete
– Example: NaCl (page 78)
Ionic Bond Example
Na LOST an
e- so it
became
more
positive
Cl GAINED
an e- so it
became
more
negative
Ionic bonds
• When ionic bonds occur the charges of the
original atoms change…
– The atom that loosing the e- now is positive
• Na is now Na+ (because it lost the e- )
• Cl is now Cl- (because it gained the e-)
• These are now called ions;
– they have become electrically charged as a result
of gaining or loosing an e-
Covalent bonds
• Atoms sharing e- is a covalent bond
• The number of bonds an atom can form usually
equals the number of additional e- that
will fill its highest NRG level
– Example (page 79)
• Hydrogen has 1e- (but its shell can hold 2)
• Oxygen has 6e- (but its shell can hold 8)
Covalent Bonds
Hydrogen 1e- = H
Oxygen 6 e- =
O
(but can hold 2 so will form 1 other bond)
(but can hold 8 so can form 2 other bonds)
Remember that they want to fill their shells!
Hydrogen can fill its shell if it takes some from oxygen
BUT oxygen doesn’t want to give one up cause then it is REALLY
unstable…
SO they share!! (yay)
WATER
HO H
Covalent Bonds
4.3-4.4 mini book
7 pages Due Friday 9/21
– Ionic bonds
– Covalent bonds
– Chemical reactions
– Structure of water
– 2 pages for life supporting properties
– Last page pH
Molecules
• 2+ atoms held together by covalent bonds
form molecules
– Chemical formula
• Number and type of atoms in molecule (H2O)
– Structural formula
• How atoms are linked by bonds (H-O-H)
– Space Filling Model
• Spheres symbolize
Stop
Chemical Reactions
• Molecules can become rearranged into other
molecules as bonds break (absorb NRG from environment)
or form (release NRG from environment)
– “Chemical reactions” result in the formation of 1
or more new substances
Chemical reactions
• Formation of water
Reactants
H
O
+
Products
2(H2O)
*Chemical RXNs neither create nor destroy
atoms, but rearrange them!!
Play-dough Chemical Bonds!
Do you remember…
• What is the difference between an ionic
bond and a covalent bond?
• Na is now Na+… what happened? What is
Na+ now called?
•
O
can form how many bonds? What is
this type of bond called?
• Draw what a carbon atom looks like (label
protons, neutrons, nucleus, electrons)
– Atomic # = 6
4.4 Unique Properties of Water
• All living things depend on water
• Earth’s abundance of water is a major
reason why it supports life (as we know it)
• 2 major parts to water’s properties
– Structure
– Interactions of its molecules
The Structure of Water
Giant Post Its!!
1.
2.
3.
4.
Table 1 Structure of water
Table 2 Cohesion & Adhesion
Table 3 Temperature Moderation
Table 4 Low Density of Ice & ability to
dissolve other substances
5. Table 5 Acids, Bases and pH, buffers
6. Sum up section 4.4
Future Outlook…
• Due Tomorrow- 4.3 CC
• Due Wednesday- 4.4 P.R. (5)
• TUESDAY 9/22 Chapter 4 Test!
Exit ticket
• Fill in where the electrons would be for
sodium (Na)
– Atomic Number = 11
3
2
1
Na