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