8.2%20Ionic%20Bonding

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8.2 Ionic Bonding
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Ionic Bonds

• Ionic bonds are made between metal and non-metal
  atoms
• Electrons are transferred from the metal atom to
  the non-metal atom
• Metal atoms lose electrons form positive ions
  called cations.
• Non metal atoms gain electrons form negative ions
  called anions.

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Metals

• Metals atoms lose electrons to form positive ions
  (an atom that loses or gains electrons) called
  cations.
• E.g., Beryllium (Be) Group 2
• Neutral atom Positive ion
• 4 Ps 4 Ps
• 4- Es 2- Es
• 0 2
• Valence Electrons
• The electrons in the outer shell of an atom,
  which determines its power to combine with other
  elements

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Non-metals

• Non-metal atoms gain electrons to form negative
  ions called anions.
• E.g., Carbon (Ca) Group 14
• Neutral atom Negative ion
• 6 Ps 6 Ps
• 6- Es 10- Es
• 0 4-

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An example of ionic bonding..

• Let us consider the bonding in the substance
  sodium chloride.
• Na Cl- NaCl-
• In this reaction the sodium (Na) atom loses 1
  electron while the chlorine atom accepts the
  electron in the transfer process.

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NaCl

• Thus we can say that sodium chloride is an ionic
  compound

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NaCl

• Cl-
• Chloride ion
• This charged atom contains
• 17 Protons
• 18- Electrons
• 1

• Na
• Sodium ion
• This charged atom contains
• 11 Protons
• 10- Electrons
• - 1

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Sodium Chloride

• Thus NaCl
• Once these two ions (An atom that has become
  charged be gaining or losing one or more
  electrons) have been formed, they will attract
  each other because of their opposite charges

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CaO

• Ca2 O2- Ca2O2-
• In this reaction the calcium (Ca) atom loses 2
  electrons while the oxygen (O) atom accepts the
  two electrons in the transfer process.

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• Thus we can say that calcium oxide is an ionic
  compound

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Calcium Oxide

• Ca2 Calcium ion O2- Oxide ion
• 20 Protons 8 Protons
• 18- Electrons 10- Electrons
• 2 2-
• Once these two ions have been formed, they will
  attract each other because of their opposite
  charges.
• There is an electrostatic attractive force
  present (like charges repel and unlike charges
  attract) that creates the chemical bond in the
  NaCl and CaO,called an ionic bond.

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Lets try one..

• Magnesium and Fluorine
• Metal Non-metal
• 12 Protons 9 Protons
• 10- Electrons 10- Electrons
• 2 1-
• Mg2 F1- Mg2F1-
• Chemical name Magnesium fluoride
• Chemical Formula MgF2

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• Group 1 elements form cations with one positive
  charge.
• Group 2 elements form cations with two positive
  charges.
• Group 3 elements form cations with three positive
  charges.
• Group 17 elements form anions with one negative
  charge.
• Group 16 elements form anions with two negative
  charges.
• group 15 elements form anions with three negative
  charges.
• Group number on the periodic table indicates the
  number of electrons the atom will lose or gain.

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Figuring out Ionic Charge

• For metals, its the same as thegroup number
  (the column number).
• For non metals, the charge is equal to whatever
  number needs to be addedto the group number to
  get 8. Group 8, (the noble gases), dont form
  ions asthey do not need to gain any electrons to
  have a full outer shell

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More to try..

• Potassium and Sulfur
• Aluminium and Chlorine
• Aluminum and Oxygen
• Calcium and Fluorine

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Bonding in Ionic Compounds

• According to the ionic electrostatic model,
  solids such as NaCl consist of positive and
  negative ions arranged in a crystal lattice.
• Each ion is attracted to neighbouring ions of
  opposite charge, and is repelled by ions of like
  charge this combination of attractions and
  repulsions, acting in all directions, causes the
  ion to be tightly fixed in its own location in
  the crystal lattice.
• Sodium metal reacts with chlorine gas in a
  violently exothermic reaction to produce NaCl
  (composed of Na and Cl- ions)
• 2Na(s) Cl2(g) -gt 2NaCl(s)