IONS and E config

1
IONS and E config

• Ions are atoms that have lost or gained
  electrons.
• Remember that the number of protons cannot
  change for an element.
• When an atom gains more electrons than the number
  of protons it has it will have a negative charge.

2

• When an element loses more electrons than the
  number of protons it has, it will have a positive
  charge.
• What drives atoms to give away electrons or take
  on more?

3
Driving Force

• Full Energy Levels are very low energy
• Noble Gases have full orbitals
• Atoms behave in ways to achieve noble gas
  configuration

4
Ionic Size

• Cations are positive ions
• Cations form by losing electrons
• Cations are smaller than the atom they come from
• Metals form cations
• Cations of representative elements have noble gas
  configuration.

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Ionic size

• Anions are negative ions
• Anions form by gaining electrons
• Anions are bigger than the atom they come from
• Nonmetals form anions
• Anions of representative elements have noble gas
  configuration.

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Configuration of Ions

• Ions of representative elements have noble gas
  configuration
• Na is 1s22s22p63s1
• Forms a 1 ion - 1s22s22p6
• Same configuration as neon
• Metals form ions with the configuration of the
  noble gas before them - they lose electrons

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Configuration of Ions

• Non-metals form ions by gaining electrons to
  achieve noble gas configuration.
• They end up with the configuration of the noble
  gas after them.

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Group trends
H1

• Adding energy level
• Ions get bigger as you go down

Li1
Na1
K1
Rb1
Cs1
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Periodic Trends

• Across the period nuclear charge increases so
  they get smaller.
• Energy level changes between anions and cations

N3-
O2-
F1-
B3
Li1
C4
Be2
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Keeping Track of Electrons

• The electrons responsible for the chemical
  properties of atoms are those in the outer energy
  level.
• Valence electrons - The s and p electrons in the
  outer energy level.
• Core electrons -those in the energy levels below.
  
• Basis for shorthand

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Keeping Track of Electrons

• Atoms in the same column
• Have the same properties because
• Have the same outer electron configuration.
• Have the same valence electrons.
• Found by looking up the group number on the
  periodic table.
• Group 2A - Be, Mg, Ca, etc.-
• 2 valence electrons

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Lewis Dot diagrams help us determine the charge
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Electron Dot diagrams

• A way of keeping track of valence electrons.
• How to write them
• Write the symbol.
• Put one dot for each valence electron
• Dont pair up until they have to

X
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The Electron Dot diagram for Nitrogen

• Nitrogen has 5 valence electrons.
• First we write the symbol.

N

• Then add 1 electron at a time to each side.

• Until they are forced to pair up.

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Write the electron dot diagram for
F Ne He

• Na
• Mg
• C
• O

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Electron Configurations for Cations

• Metals lose electrons to attain noble gas
  configuration.
• They make positive ions.
• Na 1s22s22p63s1 - 1 valence electron
• Na 1s22s22p6 -noble gas configuration

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Electron Dots For Cations

• Metals will have few valence electrons

Ca
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Electron Dots For Cations

• Metals will have few valence electrons
• These will come off

Ca
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Electron Dots For Cations

• Metals will have few valence electrons
• These will come off
• Forming positive ions

Ca2
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Electron Configurations for Anions

• Nonmetals gain electrons to attain noble gas
  configuration.
• They make negative ions.
• S 1s22s22p63s23p4 - 6 valence electrons
• S2- 1s22s22p63s23p6 -noble gas configuration.

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Electron Dots For Anions

• Nonmetals will have many valence .electrons.
• They will gain electrons to fill outer shell.

P
P3-
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Practice

• Use electron dot diagrams to show how the
  following form ions
• Al
• Cl
• C

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Stable Electron Configurations

• All atoms react to achieve noble gas
  configuration.
• Noble gases have 2 s and 6 p electrons.
• 8 valence electrons .
• Also called the octet rule.

Ar