Atoms and Molecules 2.1 Elements and Atoms. Why do we need to study chemistry in a biology class? ...

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!