unit 1 - structure and bonding

Question 1

molecular compounds

Answer 1

• where the atoms are bonded together
  eg water, ammonia, methane

Question 2

ionic compounds

Answer 2

• where many ions (charged atoms) are held together in a regular structure
  e.g sodium chloride

Question 3

covalent bonding

Answer 3

between one non metal and another non metal

Question 4

properties of simple covalent compounds

Answer 4

1. liquids or gases at room temp have low melting and boiling points
   
   • intermolecular forces are very weak
     —> not much energy needed to move molecules far apart
2. don’t conduct electricity
   
   • no free moving electrons/ions present to carry the electrical current

Question 5

ionic bonding

Answer 5

between one metal and a non metal
- held together by electrostatic forces between oppositely charged ions

Question 6

properties of ionic compounds

Answer 6

1. high melting and boiling points
   —> ions are attached to each other by strong electrostatic forces between
   = large amount of energy needed to separate them
2. crystalline solids at room temp
   —> regular arrangement of ions in a lattice of ions with opposite charges next to each other
3. conduct electricity when molten/dissolved in water
   —> in liquids, ions are free to move about
   —> they can move towards the electrodes when a voltage is applied
4. soluble in water
   —> water is attracted to charged ions = many ionic solids dissolve