Atoms combining

Atoms combining

1. Describe the formation of ions by electron loss or gain

   • If an atom contains more electrons than protons the atom has a negative charge. If the atom contains fewer electrons than the protons the atom has a positive charge. Ions are a group of atoms that carry a positive or negative charge.

2. Describe the formation of ionic bonds between elements from Groups I and VII

3. Explain the formation of ionic bonds between metallic and non-metallic elements

   • Ionic bonds are the bonds that form between opposite charges. A metal reacts with non-metal to form an ionic-compound.The metal ions lose electron. The non-metal gain them. The ions form a lattice. The compound has no over all charge.

4. State that non-metallic elements form non-ionic compounds using a different type of bonding called covalent bonding

   • Same nuclei attract the shared electrons -this a strong force of attraction hold the 2 atoms together. The force of attraction is called covalent bonds.

5. Draw dot and cross diagrams to represent the sharing of electron pairs to form single covalent bonds

   • Single bonds

6. Draw dot and cross diagrams to represent the multiple bonding

7. Describe the differences in volatility, solubility and electrical conductivity between ionic and covalent compounds

   • Volatility
     • Ionic bonds have high melting and boiling points.
     • Covalent bonds have low melting and boiling points.
   • Solubility
     • Ionic bonds tend to be soluble in water.
     • Covalent bonds tend to be insoluble.
   • Electrical Conductivity
     • Ionic bonds conduct electricity when melted or dissolved in water.
     • Covalent bonds do not conduct electricity.

8. Describe the giant covalent structures of graphite and diamond

   • Graphite
     • ~Each carbon attached to three other carbon atoms ~Hexagonal ring layered lattice structure ~Delocalised electrons within each layer ~Weak intermolecular forces between the layers.
   • Daimond
     • ~Each carbon forms four covalent bonds with other carbon atoms ~Each carbon has a tetrahedral arrangement ~All electrons are localised in covalent bonds.

9. Relate their structures to the use of graphite as a lubricant and of diamond in cutting

   • DIamond
     • ~Each atom is held place by 4 strong covalent bonds. It has a high melting point.It also cannot conduct electricity.
   • Graphite
     • ~Each atom is held in place by 3 strong covalent bonds. It has a low melting points. It also can conduct electricity.

10. Describe the structure of silicon(IV) oxide (silicon dioxide)

    • Silicon is similar to diamond. Each silicon atom bonds covalently with 4 oxygen atoms. Each oxygen atoms bonds covalently with 4 silicon atoms and the result is a very hard matarial with a high melting point.

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