112707 Inquiry Science 9

1
Describe 3 ways that atoms can become happy.

• A happy atom is an atom that has a full outer
  shell of electrons
• Steal e- (Ionic Bond)
• Metals are losers, Non-metals are stealers
• Ex. Na Cl
• Share e- equally (Non-polar Covalent)
• Same atoms or atoms w/ similar electronegativity
• Ex. H H
• Share e- unequally (Polar Covalent)
• One atom with higher electronegativity
• Ex. H Cl

2

• Review
• What are the 3 Rules about charges?
• All Matter Has Charges (b/c all matter is made of
  atoms)
• Opposite Charges Attract -
• Like Charges Repel

What is a 4th Rule? Only e- can transfer!


3
Why does your hair stand straight up after you
rub a balloon in it? Explain using words and
pictures.
4

• Electrons are transferred from your hair to the
  balloon. This gives the balloon a negative
  charge.
• Your hair becomes more positively charged.
  Opposite charges attract!
• Since each hair now has a like charge (positive),
  the hairs repel each other and they separate.

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Before Charging
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Fine Stream of Water
7
Why does water bend towards the charged object
when the objects have different charges?
8
Water is a Polar Molecule!
Its attracted to both positive AND negative
charges
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9
Ernest Rutherford 1911
What were his 3 BIG IDEAS??
10
Rutherford Experiment
1911
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Microscopic View
12
From his Gold Foil experiment Ernest Rutherford
Discovered

• Atoms have a very small nucleus (center of atom)
• Nucleus is positively charged (protons)
• Atoms are mostly empty space

13
Neils Bohr Bohr Model showed e- exist ONLY in
specific energy levels (shells)
14
Higher Energy
Lower Energy
e- makes a Bigger jump gives off more energy
e- makes a smaller jump gives off less energy
15
Groups, Families and Periods
16
Compare/contrast Electronegativity and Ionization
Energy.

• Electronegativity A measure of an atoms
  hunger for electrons.
• Florine (electronegativity 4.0) has the
  greatest hunger for an electron. Neon, with 8
  valence e-, has no electronegativity.

The Cookie Monster would have a lot of
Electronegativity!
Me like electrons!!
17
Highest
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Ionization Energy A measure of electron
greediness. The higher the ionization energy,
the more energy it takes to remove electrons.
Theyre My electrons and Im keeping them!
Trump would have a lot of ionization energy!
Metals (left side of periodic table) have lower
ionization energies give up electrons way more
easily than non-metals (right side of periodic
table).
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How do they compare? Both increase left to right
and from bottom to top
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The difference in electronegativity between two
atoms will determine the type of bonding that
occurs
lt 0.5
gt2.0
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Electronegativity Difference Tug of War
Equal Strength Non-Polar Covalent
Sharing e-
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One Stronger Polar Covalent
Not Equal Strength Polar Covalent Sharing e-
but one is being an e- HOG
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Stealing e- Ionic
Why share e- if youre strong enough to steal?