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Ionic Bonding

Ionic Bonding. Chapter 5. What is an ion?. An atom that has lost or gained electrons is called an ion. An atom that loses electrons has more protons (p + ) than electrons (e - ) and is therefore positive. A positive ion is called a Cation. Metals tend to form cations.

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Ionic Bonding

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  1. Ionic Bonding Chapter 5

  2. What is an ion? • An atom that has lost or gained electrons is called an ion. • An atom that loses electrons has more protons (p+) than electrons (e-) and is therefore positive. • A positive ion is called a Cation. • Metals tend to form cations. • An atom that gains electrons has more e- than p+ and so is negative • A negative ion is called an Anion. • Non-metals tend to form anions.

  3. The Octet Rule “Atoms are most stable when their valence shell (outer s and p orbitals) is filled.” s2p6 = 8 electrons Atoms will gain, lose, or share electrons to satisfy the octet rule. • The number of electrons gained or lost is the magnitude of the charge

  4. The Formation of Ions M  M+ (cation) + e- Na 1s2 2s2 2p6 3s1 Applying the octet rule… Na+ 1s22s2 2p6 N + e- N- (anion) F 1s2 2s2 2p5 Applying the octet rule… F- 1s2 2s2 2p6

  5. What ion would these atoms make? • Rb • Cl • N • O • Be • Li • C

  6. Ionic Compounds • When two ions come together with equal and opposite charges, they form an ionic compound. • Ionic compounds are also known as “salts”. • This attraction is called an electrostatic attraction. • This is kind-of like a magnet.

  7. Ionic Bond • When two oppositely charged ions come together, they form a bond. • Electrons are transferred from one atom to another making a cation and an anion. • Typically between Metals and Non-metals. • Ions must be equally and oppositely charged. • Ex. Na+ + Cl- = NaCl

  8. Ions are Formed

  9. Ionic Compounds (a.k.a. salts) • Ionic compounds are actually groups of ions coming together in repeating formula units to create a crystalline lattice structure. • Like legos. NaCl - NaCl - NaCl NaCl - NaCl • This crystalline lattice is what gives ionic compounds their unique properties.

  10. Lattice Energy • When an ionic bond is formed, energy is lost. • This energy is called lattice energy.

  11. Cl- Na+ Na+ Cl- Cl- Cl- Na+ Na+ Ionic Properties • white • Solid, Crystalline • Nonvolatile • High melting point • Soluble in water • Good conductor of electricity in solution • Solids are brittle

  12. M.P. and B.P. • Salts have a high melting point (m.p.) and boiling point (b.p.) because it takes a large amount of energy to break the bond of the crystalline solids.

  13. Soluble • Salts are soluble in water. • That means that the ions will dissociate or dissolve. • When they are dissolved in water, they solution is called an aqueous solution and is abbreviated (aq) • NaCl in H2O gives you Na+ and Cl-

  14. Conductivity • Conductivity is a measurement that determines the concentration of ions in a solution. • In order to conduct electricity, a solution needs to have • Charged particles that can • Move freely

  15. Brittle • Salts are very brittle, meaning that they will crack or fracture under pressure. • Cleavage: they will fracture with a clean plane

  16. Do I have an ionic compound? Natural State Solid Gas, Liquid Hard Soft Fracture Crumble Not Ionic MP High Low Conductive Yes No Ionic

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