1. How do you know how many valence electrons an atom has?
Day 2 3-20
Notation used to show an abbreviated version of an elements valence electron arrangement
H
F
O
Notation used to show an abbreviated version of an elements valence electron arrangement
First determine number of valence electrons.
Valence electrons are represented with dots around the element’s symbol.
H
F
O
Notation used to show an abbreviated version of an elements valence electron arrangement
2 e-s. can fit per side (you can think of each side of the symbol as an orbital)
H
F
O
H
F
O
In order to bond an element must be able to give AND take an electron.
In order for a bond to form an atom must be able to “give” an electron and “take one”
F Both can bond once
H
Examples:Sodium = can bond ____
Phosphorous = can bond ____
Aluminum = can bond ____
Fluorine = can bond ____
You Practice:
N =
B =
C =
Lewis Dot Structure Can Bond?
Using Lewis dots to represent bonds (Lewis dots for compounds):
Na Cl
Na ClShared electrons (bonds) are represented with a line
Suggested Steps:1. Do each individual Lewis dot structure and determine how many times each element can bond2. Look for ways to make everyone happy3. Lewis dot structure must match formula!!!
B. Practice:
potassium and fluorine bond
magnesium and chlorine bond
lithium and oxygen bond
hydrogen and oxygen bond
READ section 7.1 and complete #s 1-8 on page 199
-Due Friday 3-27
BINDERS!!!
1. The halogens all have __ valence which means they all want to ______________.
Day 6 3-26
7
gain one electron
How do elements combine to form compounds?
Electrostatic Force – an interaction between charged particles
Opposites –
Like charges –
Attract
Repel
What happens when atoms collide?Valence electrons interact.
Valence electrons dictate
reactivity!
Chemical bond – A mutual electrical attraction between the nuclei and valence electrons of different atoms that binds them together … electrostatic force
Opposites Attract!!!
Nuclei = _______________ charge
Electrons = _______________ charge
positive
negative
Holding it all together
But Why Bond at all?
Atoms want a full set of valence electrons (8) and they can share (bond) to
get them!!!
~ octet rule
Why bonds and ions? Achieving electrical and energetic stability.Lone electrons – high potential energy - BAD
Br
Electron pairs – stable - Good
3 main bond types:• Ionic
• Polar covalent
• Nonpolar covalent
Electrostatic Force – an interaction between charged particles
Opposites –
Like charges –
Attract
Repel
Cation – positive ion
Anion – negative ion
Ions – charged particles
Collision – Ions
Br
LiBANG
Br(-)
(+)
Li
Br
LiBANG
BrLi
But they don’t separate … WHY? + -
Electrostatic Force
Ionic bonds – Chemical bonds that result from the electrical attraction between large numbers of cations and anions
Cation – ?
Anion – ?
Atoms Only transfer elecs. (form ions) when one atom has a very strong attraction for elecs. (wants them a lot more)
Electronegativity – measure of atom’s ability to attract electrons
Electronegativity
Electronegativity P. T. (page 181)
Ionic bonds most commonly form between metals and
nonmetals!
Ionic bonds are made up of charged pieces (ions)
Ions can be made up of one element or a combination of elements (polyatomic ions)
Ionic Compounds:
high melting points – strong bonds
Brittle
dissolve in water to produce mobile ions – good conductors
1. Draw the Lewis dot structure for chlorine.
Day 1 3-27
2. Draw the Lewis dot structure for oxygen – use your notes packet if needed.
READ section 7.1 and complete #s 1-8 on page 199
-Due Friday 3-27
BINDERS!!!
Quarterly Exam = Tuesday 3-31
http://www.youtube.com/watch?v=QqjcCvzWwww
http://www.youtube.com/watch?v=bK9nMHTLhmk
http://www.youtube.com/watch?v=BCYrNU-7SfA
Electrostatic Forces
L A B
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