1. How do you know how many valence electrons an atom has? Day 2 3-20.
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Transcript of 1. How do you know how many valence electrons an atom has? Day 2 3-20.
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1. How do you know how many valence electrons an atom has?
Day 2 3-20
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Notation used to show an abbreviated version of an elements valence electron arrangement
H
F
O
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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
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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
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H
F
O
In order to bond an element must be able to give AND take an electron.
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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
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Examples:Sodium = can bond ____
Phosphorous = can bond ____
Aluminum = can bond ____
Fluorine = can bond ____
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You Practice:
N =
B =
C =
Lewis Dot Structure Can Bond?
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Using Lewis dots to represent bonds (Lewis dots for compounds):
Na Cl
Na ClShared electrons (bonds) are represented with a line
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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!!!
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B. Practice:
potassium and fluorine bond
magnesium and chlorine bond
lithium and oxygen bond
hydrogen and oxygen bond
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READ section 7.1 and complete #s 1-8 on page 199
-Due Friday 3-27
BINDERS!!!
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1. The halogens all have __ valence which means they all want to ______________.
Day 6 3-26
7
gain one electron
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How do elements combine to form compounds?
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Electrostatic Force – an interaction between charged particles
Opposites –
Like charges –
Attract
Repel
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What happens when atoms collide?Valence electrons interact.
Valence electrons dictate
reactivity!
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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
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But Why Bond at all?
Atoms want a full set of valence electrons (8) and they can share (bond) to
get them!!!
~ octet rule
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Why bonds and ions? Achieving electrical and energetic stability.Lone electrons – high potential energy - BAD
Br
Electron pairs – stable - Good
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3 main bond types:• Ionic
• Polar covalent
• Nonpolar covalent
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Electrostatic Force – an interaction between charged particles
Opposites –
Like charges –
Attract
Repel
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Cation – positive ion
Anion – negative ion
Ions – charged particles
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Collision – Ions
Br
LiBANG
Br(-)
(+)
Li
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Br
LiBANG
BrLi
But they don’t separate … WHY? + -
Electrostatic Force
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Ionic bonds – Chemical bonds that result from the electrical attraction between large numbers of cations and anions
Cation – ?
Anion – ?
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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
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Electronegativity P. T. (page 181)
Ionic bonds most commonly form between metals and
nonmetals!
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Ionic bonds are made up of charged pieces (ions)
Ions can be made up of one element or a combination of elements (polyatomic ions)
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Ionic Compounds:
high melting points – strong bonds
Brittle
dissolve in water to produce mobile ions – good conductors
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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.
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READ section 7.1 and complete #s 1-8 on page 199
-Due Friday 3-27
BINDERS!!!
Quarterly Exam = Tuesday 3-31
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http://www.youtube.com/watch?v=QqjcCvzWwww
http://www.youtube.com/watch?v=bK9nMHTLhmk
http://www.youtube.com/watch?v=BCYrNU-7SfA
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Electrostatic Forces
L A B