Commonly Unclear information Why O3 blocks UV better than other molecules. CFC and Ozone Correlation between Atoms and Ozone

Problem Allotropes Isotopes – What are they and how to

differentiate them Groups and Periods Core vs. Valence Electrons Charge of Atoms

Ozone and Atoms … Why? So what? Why should we discuss

atomic structure? Answer: In order to understand the

differences between oxygen and ozone AND in order to gain an understanding of How ozone filters out UV light …

WE need to consider its Structure

Allotropes of Carbon

Diamond Graphite Buckminster Fullerenes “Bucky-balls”

Isotopes Tritium & Deuterium are isotopes

of HydrogenIsotopes- Same number of Protons …

differ in number of Neutrons

11H - Hydrogen

21H – Deuterium

31H - Tritium

Your Turn

Specify the number of protons and neutrons in the following isotopes Uranium-235 (AKA 235

92U) Carbon-14 Iodine-131 Sulfur-36

Valence and Core electrons

Alright, What is this about valence and core electrons?

Electrons

1 Proton

1 electron

Add one proton

Hydrogen2 Protons And 2 neutrons to stabilize

2 electron

Helium

Add one proton

2 electrons

1 electron

3 Protons And 4 neutrons to stabilize

Lithium

Your Turn Predict the number of neutrons,

protons, total electrons, and valence electrons in:

Ca AlAsTe

Alright …. After this excursion into the atom, we get

to our primary motivation for studying the atom … MOLECULAR STRUCTURE.

Molecular structure is the result of ATOMS bonding to each other

Remember - Molecular structure accounts for Properties of molecules.

Think allotropes of carbon.

Covalent Bonding

Bonding is the result of sharing of valence electron pairs!

Systematic Drawing of Lewis Structures Lewis structures show bonding and

placement of electrons in molecules.1. Sum Valence electrons for all atoms in the

molecule2. Draw the skeleton structure showing which atoms

are bonded to each other. (Atom written first – generally center)

3. Complete the octet of all atoms surrounding the central atom

4. Place any left over electrons on the central atom5. If the central atom has less than 8 electrons,

complete the octet of the central atom by sharing additional pairs of electrons with the outer atoms.