Transcript Atoms and molecules

Atoms and Molecules
2.1 Elements and Atoms
Why do we need to study chemistry in a biology class?
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Elements are _____
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Matter is _____
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Six are basic for life
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Solid, liquid, gas
92 are natural
CHNOPS
Others: Na, K, Ca,
Fe, Mg
Periodic table
What are atoms?
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Smallest part of an _________
Important terms
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Atomic symbol
Atomic mass (not weight)
Atomic number
Atomic particles include:
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Electron shell
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What is a mole?
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Used as a standardizing unit
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Avogadro’s number
6.023 X 1023
We’ll play with this later…
What are isotopes?
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Different number of ___
Same atomic _________
Different atomic ______
Sometimes radioactive
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Used as a tracer (e.g. I)
How are electrons arranged in an atom?
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Bohr diagrams
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These show orbitals
1st energy shell =
___ electrons
2nd energy shell =
___ electrons
3rd energy shell =
___ electrons
Octet rule
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Determines bonding
behavior
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Two or more atoms
bonded together =
_______
Atoms and Molecules
2.2 Bonds form molecules
What is a molecule?
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Two or more _______ sharing
electrons
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Molecules are the smallest form
of a _______
Diatomic molecules
Several types of bonds
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Ionic
Covalent
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Polar
Non-polar
Hydrogen
What is an ionic bond?
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One atom ______
an electron
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Creates ions
Bond = attraction
between opposite
charges
What is a covalent bond?
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Two atoms ________ electrons
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Single
Double
Triple
Two types
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Non-polar
Polar
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Water is best example
What are hydrogen bonds?
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Not a true bond
Due to the polar covalent nature of molecule
Atoms and Molecules
2.3 Properties of water
What are the properties of water?
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Polar
Universal solvent
Cohesion
Adhesion
High heat capacity
High surface tension
Solid water is less dense than
liquid water
What is polarity again?
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Other molecules may be defined as
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Hydrophobic
hydrophilic
Why is water a good solvent?
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First some terms
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Solution = ______ + _____
Water is polar…
What is the difference between cohesion and adhesion?
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Cohesion
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Due to ____ bonding
Adhesion
What is high heat capacity and why is it important?
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Calorie = amount of heat
needed to raise ______ of
water by ______.
Hydrogen bonds change
melting and boiling points
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Without hydrogen
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Would melt at -100 degrees C
Would boil at -91 degrees C
What is high surface tension?
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Due to hydrogen bonds
Why is it important that liquid water is more dense
than solid water?
Atoms and Molecules
2.4 Acids, bases and pH
What is pH?
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= -log[H+]
pH scale
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How was it created?
What are acidic solutions?
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Donate________________
What are basic solutions?
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Either take up ____ or
release _____
What is a buffer?
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Important in our blood!