In This Lesson:
Compounds,
Electron
Configuration
(Lesson 3 of 9)
Today is Tuesday,
th
September 15 , 2015
Pre-Class:
We will be starting with a concept map
today, followed by some
information…and stuff…
Today’s Agenda
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Concept map review.
Review of Guiding Questions.
Understand compounds.
Diagram electron configuration.
Learn bonds (soon).
Properties of Water (not as soon but still soon).
• Where is this in my book?
– Academic: p. 35 and following…
– Honors: p. 19 and following…
By the end of this lesson…
• You should be able to identify the basic
structure of compounds.
• You should be able to properly place electrons
around a nucleus with respect to energy
levels.
Atom Concept Map Review
• Everyone should copy this down.
– Makes for a great study guide…
• Volunteer(s)?
Guiding Questions
• Recently we looked at a series of what I called
Guiding Questions.
• For review, here they are…
Guiding Questions
(Write these down)
1. Is it okay to use the number of electrons as a
measure of atomic number?
2. What happens if you remove or add a proton?
3. What happens if you remove or add a neutron?
4. What happens if you remove or add an electron?
Guiding Question 1
• Is it okay to use the number of electrons as a
measure of atomic number?
– No – in ions, the number of electrons does not
equal the atomic number.
Guiding Question 2
• What happens if you remove or add a
proton?
– Adding a proton changes the element!
– This does not often happen in nature.
– Let’s say you have Hydrogen. It’s got one
proton.
– We add a proton, so now it has two. Which
element has two protons?
• Helium.
Guiding Question 3
• What happens if you remove or add a
neutron?
– You’ll create a new isotope.
– Same element, same number of protons, new
number of neutrons, new atomic mass.
Guiding Question 4
• What happens if you remove or add an
electron?
– You’ll create an ion.
– An ion is an electrically-charged atom.
Compounds
• As we learned recently (briefly), a compound is a
chemical combination of two or more elements.
– Examples of compounds:
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Water
Salt
Hydrochloric Acid (stomach acid)
Sulfuric Acid (“ouch” acid)
Carbon Dioxide
Carbonic Acid (similar to soda water)
Glucose (simple sugar)
Compounds
• In compounds, elements are held together by some
kind of bond (more on bonds later
today/tomorrow).
– The smallest unit of an element is called an atom.
– The smallest unit of a compound is called a molecule.**
• Compounds generally form through a chemical
reaction, in which bonds are broken, rearranged, or
formed.
– Speaking of chemical reactions…
– Video! Chemical Reactions – NOVA
Compounds vs. Elements
• Remember that writing an element is as easy
as its abbreviation:
– H, Cu, Hg, Li, He, O, C
• Writing a compound means writing all the
elements in the compound, as well as how
much are in there.
– Examples next slide…
Compounds
• Compound Examples:
– Water (H2O – 2 Hydrogen atoms and 1 Oxygen atom)
– Salt (NaCl – 1 Sodium atom and 1 Chlorine atom)
– Hydrochloric Acid (HCl – 1 Hydrogen and 1 Chlorine)
– Sulfuric Acid (H2SO4 – 2 Hydrogen, 1 Sulfur, 4 Oxygen)
– Carbon Dioxide (CO2)
– Carbonic Acid (H2CO3)
– Glucose (C6H12O6)
Making Compounds
• As we said, compounds form from bonds.
• To understand bonds, we need to understand
electron configuration.
• Electron configuration refers to how the
electrons are organized in that cloud around
the nucleus.
• Note (but not in your notebooks): What
you’re about to hear is the simplified biology
version. The chemistry version is MUCH more
complicated/realistic.
Electron Configuration
• In any given atom’s electron cloud, we say
there are energy levels or energy shells.
• By this, we mean that there are levels closer
to the nucleus (lower energy levels) and
levels further from the nucleus (higher energy
levels).
• Picture on next slide…
Electron Configuration
• The electrons in the
outermost energy
shell (however far
out that may be)
are called valence
electrons.
• Valence electrons
are the only ones
that matter in
bonding.
http://www.physics.uiowa.edu/adventure/fall_2005/oct_15-05/energy_levels.gif
Electron Configuration
• “Filling” electron shells with electrons is easy.
• You already know how to calculate the total
number of electrons in an atom or ion.
• Fill the shells in a 2-8-8 pattern.
– We won’t often be going higher than atomic
number 18 in this class.
– Example on next slide.
Electron Configuration
• Let’s fill the shells of Aluminum, atomic number
13. This means there are how many electrons in
an uncharged atom?
– 13
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Remember the 2-8-8 pattern!
First shell: 2
Second shell: 8
Third shell: 3
– 3 valence electrons, and the third shell is the valence
shell in this case.
From ChemicalElements.com
• Take a look at the aluminum
atomic diagram to the right.
What do you see?
• Another place to look:
– David’s Whizzy Periodic Table
• http://www.colorado.edu/physic
s/2000/applets/a2.html
• Linked on my website.
Electron Configuration
• Now it’s your turn.
• Fill the shells of the following atoms in your notebooks,
and write how many valence electrons there are:
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Carbon
Oxygen
Beryllium
Fluorine
Hydrogen
Helium
Neon
Magnesium
Sulfur
Electron Configuration
• Carbon (Atomic Number 6)
– 2, 4 [4 valence electrons]
• Oxygen (Atomic Number 8)
– 2, 6 [6 valence electrons]
• Beryllium (Atomic Number 4)
– 2, 2 [2 valence electrons]
• Fluorine (Atomic Number 9)
– 2, 7 [7 valence electrons]
Electron Configuration
• Hydrogen (Atomic Number 1)
– 1 [1 valence electron]
• Helium (Atomic Number 2)
– 2 [2 valence electrons]
– Notice something about helium?
• Neon (Atomic Number 10)
– 2, 8 [8 valence electrons]
– Notice something about neon and helium?
Electron Configuration
• Magnesium (Atomic Number 12)
– 2, 8, 2 [2 valence electrons]
– Notice something about magnesium and
beryllium?
• Sulfur (Atomic Number 16)
– 2, 8, 6 [6 valence electrons]
– Notice something about sulfur and oxygen?
Electron Configuration
• What’s going on with helium and neon?
– How many valence electrons?
• 2 and 8
– How many more can you fit in their outermost energy shells?
• None! The valence shells are at capacity!
• These, and all the elements in the same column below
them, are called the noble gases.
• Because their valence shells are full, they don’t really react
with anything.
– They also were among the last elements to be discovered.
• Think of a snooty “noble” person. That’s how they were
named!
Electron Configuration
• And what about their location on the periodic
table?
Electron Configuration
• Now what about Beryllium and Magnesium?
– How many valence electrons for each?
– 2!
• And how about Oxygen and Sulfur?
– 6 each!
• And what about all of their locations on the
table?
Electron Configuration
• And what about their location on the periodic
table?
Electron Configuration
• There is a pattern to the periodic table for
valence electrons!
• Work by columns (which are called groups).
• Start from the left and ignore the lower
middle part.
– The first column or group has 1 valence electron,
the second has 2, et cetera.
• Rows, by the way, are called periods.
– Hence, periodic table of elements.
Electron Configuration
1
2
2
3 4 5 6 7 8
Dmitri Mendeleev
• Looks like he was on
to something when
he arranged the
table…
http://reich-chemistry.wikispaces.com/file/view/Dmitri_Mendeleev.jpg/98117907/Dmitri_Mendeleev.jpg
One last thing…
• If you’re dealing with an ion (say for example
Al3+), make sure you get the new number of
electrons.
• Al3+ has 13 protons and 10 electrons, so the
arrangement is:
– First shell: 2
– Second shell: 8
• Total: 10 electrons
A “Trailer” for Next Class
• TED: George Zaidan and Charles Morton –
How Atoms Bond
And so now we do
the Review and WhipAround…
• First, play Electron Configuration Matching
Game on Quia.
• Then, try Atomic Structure and Electron
Configuration Battleship.
• Then, try Atomic Structure Review Quiz.
– Write both your names in the survey question.
• Find some space in your notebook and write
down two things you learned about:
– Electron Configuration
– Compounds