What do ionic compounds form?
- ionic bond for between metals and non-metals and always make giant ionic lattices
- ions form a closely packed
- ions not free to move so the compounds do not conduct electricity when solid
- very strong chemical bonds between all the ions
What are the properties of NaCl and why?
-giant ionic structure
-high melting and boiling point due to very strong attraction between oppositely charged ions in the giant structure
when melted ions are free to move and will conduct electricity
-dissolves to form solution that conducts electricity (ions dissolve and separate so are free to move in the solution, so they carry electric current)
-Na+ and Cl- ions
What are the properties of MgO and why?
- giant ionic structure
- high melting and boiling point due to very strong attraction between oppositely charged ions in the giant structure
- Mg2+ and O2- ions (double the charge of NaCl
- higher melting point than sodium chloride:
- as it has double the charge of NaCl, so the attraction is harder to overcome
- O2- ions are smaller than Cl- ions, so ions in MgO more dense , also making the attraction harder to overcome
- when melted ions are free to move and will conduct electricity
What are ions and how are they formed?
- charge particles, can be a single atom(Cl-) or a group of atoms(NO-3)
- non metal: gain electrons to form negative ions
- metal: lose electrons to form positive ions
What is ionic bonding?
-atoms losing or gaining electrons to form charged particles (ions) which are then strongly attracted to each other (because of the attraction of opposite charges)
Why are the boiling and melting points of molecular substances low?
- atoms within the molecules are help together by very strong covalent bonds
- by contrast, the forces of attraction between these attractions are very weak
- because of these feeble intermolecular forces, they have very low boiling and melting points
What are some properties of molecular substances?
- substances formed from covalent bonding usually have simple structures (CO2)
- most are liquids or gases at room temperature
- don’t conduct electricity, because there are no free electrons or ions
