Download 1.2 Basic Atomic Theory Electrical structure of matter

Stratospheric Ozone
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What is ozone?
What does it do?
What are its properties?
How is it made?
How is it destroyed?
Why do Ozone Holes form primarily at the
poles?
Where is the ozone hole the largest?
Many, many other questions ….
Ozone?
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“ … And if prehistoric Man merely got a
sunburn, how is that we are going to destroy
the ozone layer with our air conditioners and
underarm deodorants and cause everybody to
get cancer? Obviously we’re not … and we
can’t … and it’s a hoax. Evidence is mounting
all the time that ozone depletion is, if
occurring at all, is not doing so at an alarming
rate .…”
Rush Limbaugh, 1993. See I told you so.
Basic Atomic Theory
Atoms – Derived from greek word Atomos
(indivisible).
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Simplest building blocks of matter
All atoms of a same type are identical
Atoms are not changed by chemical reactions
Atoms cannot be created nor destroyed in
chemical reactions (law of conservation of mass)
Compounds form when elements combine
Relative size of a nucleus and
an Atom
Atomic Structure
(composition)
Protons and Elements
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The number of protons in the nucleus
defines the element type.
All Atoms with the same number of
protons are the same element.
Atomic structure continued
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Let’s consider oxygen
16
8O
Molecular Models
Covalent Bonding
Systematic Drawing of Lewis
Structures
Lewis structures show bonding and placement of
electrons in molecules.
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Sum Valence electrons for all atoms in the molecule
Draw the skeleton structure showing which atoms are
bonded to each other. (Atom written first – generally
center)
Complete the octet of all atoms surrounding the central
atom
Place any left over electrons on the central atom
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.