The Magic of Matter

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The Magic of Matter

• Part 4 Where the Real Magic Lies Electrons and
  Change
• Warm-up- Short Writing
• Based on what you know about the electromagnetic
  force, describe why electrons space themselves
  out around the nucleus instead of grouping
  tightly around it.

TEKS 8.8 (B) identify the properties of an atom
including mass and electrical charge 8.9 (A)
demonstrate that substances may react to form new
substances
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Bonding Basics

• Sodium (Na, atomic number 11) is a soft metal
  that is highly reactive. It explodes on contact
  with water.
• Chlorine (Cl, atomic number 17) is a poisonous,
  corrosive, green gas used to kill soldiers in
  WW1.
• What happens when these dangerous elements are
  placed in a reaction vessel together?

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When Na is placed into a cylinder filled with Cl,
a violent reaction occurs giving off large
amounts of heat.
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Bonding Basics
The result is a crystalline substance which is
dissolved in our seas and in our veins. It is
essential for life. It makes food taste better.
We call it table salt.
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Bonding Basics

• How can it be that a metal and gas can combine to
  produce an eatable solid? The answer is that a
  chemical reaction has taken place to create a new
  substance with new properties. That means that
  chemical bonds have broken and reformed in a
  different arrangement.

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Chemistrys Big Question

• Where are the Electrons?
• To understand how atoms bond together, we must
  understand electrons.

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Electron Configurations
An atom has from 1 to 7 energy levels

• Electrons circle the nucleus of the atom in
  clouds that are a specific distance from the
  nucleus. These are called energy levels.
  Electrons always fill the lowest energy levels
  first.

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Electron Configurations

• The horizontal rows of the periodic table are
  called Periods. They are numbered from 1 to 7.
  The period an atom is in tells how many energy
  levels it has.
• Each energy level can hold only a certain number
  of electrons.
• Level 1 2 electrons, Level 2 8 electrons,
• Level 3 18 electron, Level 4 32 electrons

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Bonding Basics

• Earlier, we said that atoms normally have no
  charge because they have equal numbers of protons
  and electrons. However, atoms can gain or loose
  electrons. The only place this electron change
  can happen is in the outer most energy level.
  Electrons in the outer energy level are called
  the valence electrons.

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Bonding Basics

• The vertical columns of the periodic table are
  called Families or Groups. The are numbered
  across the top of the periodic table. Elements
  in the same family behave similarly because they
  have the same number of valence electrons.

Key Point!
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Bonding Basics

• The elements in group 8A, on the far right side
  of the periodic table, all have full outer energy
  levels. They are called the Noble Gasses.
• They are happy having full outer energy levels.
  They wont take any more electrons from any other
  atoms, and they arent giving any of theirs away.
  Therefore, these atoms do not react readily with
  other atoms, or with each other.

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Bonding Basics

• How Noble Gasses see themselves.

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Bonding Basics

• Like some people, atoms have a goal.
• Atoms want to have FULL outer energy levels!
• Full energy levels are more stable, and atoms are
  all about stability.

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Bonding Basics

• The key to understanding chemistry
• Atoms will loose or gain electrons in order to
  have the same number of valence electrons as the
  Noble Gas closest to them on the Periodic Table.

Key Point!
Thats all you need to know to predict most
chemical reactions.
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Bonding Basics

• The Noble Gasses have 8 electrons in their outer
  most energy levels. Since all atoms want to be
  like the Noble Gas closest to them, we can say
  that atoms will gain or loose electrons in order
  to have an octet (8) of valence electrons. This
  is called the Octet Rule.
• There are exceptions H and He have only one
  energy level that can only hold 2 electrons.
  Also the Transitions Metals in Groups 3B-12B do
  not follow the rule. Youll find out why when
  you take Chemistry in high school.

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Bonding Basics

• Example 1
• Na, atomic 11, is in Group 1A. It has one
  valence electron in its outer shell. The Noble
  Gas it is closest to is Neon, atomic 10. Na
  must loose one electron to have the same number
  of electrons as Neon, and that is what Na does in
  most reaction.

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Bonding Basics

• Example 2
• Chlorine , atomic 17, is in group 7A. It has 7
  valence electrons in its outer shell. Argon,
  atomic 18 is the closest gas to Chlorine, so
  chlorine must gain 1 electron to be like Argon.
  That is what chlorine does in most reactions.

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Now you try!

• Decide if the following atoms will gain or loose
  electrons in a chemical reaction, and how many

• Potassium (K, 19)
• Phosphorous (P, 15)
• Magnesium (Mg, 12)

• Loose 1 electron
• Gain 3 electrons
• Loose 2 electrons