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Published byLiliana Mills Modified over 7 years ago
1/10/11 Last week’s winners: 4 th period Catalyst: 1. What does an atom have to do to become a cation? 2. What does an atom have to do to become an anion? Objective: Describe the properties of ionic compounds and relate the properties to the chemical structure. Homework: Complete Cornell notes on chapter 5, section 2 by Wednesday
How could ions come together to form compounds? Rules: – Opposites attract – All compounds are neutral in charge – When combined form salts
How are electrons transferred between atoms? Ionization energy=energy to remove an electron Electron affinity=energy to add an electron Negative ions release energy when adding electrons, but less than required
What are the steps of forming the bond? Endothermic (energy needed) steps: Cations formed and non-metal atoms separated from one another Exothermic (energy releasing) steps: Electrons added to non-metal atoms to form anions Anions and cations form bonds producing lattice energy
What are the properties of salts? Solid at room temperature High melting and boiling points Dissolved and liquid salts conduct electricity Hard and brittle
Why do salts have these properties? Strong bonds require a lot of energy to separate ions to melt or boil Because atoms have charge, they conduct electrical current well when they can move freely Strong bonds and alternating cations and anions make salts hard, but brittle
Summary questions 1.What force holds together ions? 2.How does an ionic bond form? 3.Why do dissolved ions, but not solid ionic compounds, conduct electricity? 4.Why will two metals or two non-metals not form an ionic bond? 5.Which metals, alkali or alkaline earth metals, will more easily form an ionic bond?
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