Bonding Flashcards
What holds a metal lattice together?
The electrostatic attraction of negatively charged electrons for positively charged ions.
Explain why metals are lustrous.
When light energy strikes the surface of a metal, electrons absorb and then re-emit this light energy.
Explain why metals are malleable and ductile.
The attraction between the positive metal ions and the delocalised electrons is non-directional. If a force is applied to the metal lattice that results in movement of some of the metal ions, the delocalised electrons also move allowing the shape of the lattice to change without breaking.
What are some additional properties of transition metals (groups 3-12)?
Transition metals tend to be harder and have higher melting points compared with group 1 and 2 metals. This is because bonds in transition metals are usually stronger because the atoms are smaller in size, due to a greater nuclear charge. They can therefore pack together more tightly.
Transition metals often form ions with multiple valencies. Copper (I) and Copper (II), iron (II) and iron (III), gold (I) and gold (III) etc.
The ions of transition metals and sometimes the metals themselves may be coloured. (copper = salmon pink, gold = yellow, copper (II) ions = blue,
manganese (II) ions = pale pink, chromium (III) ions = green etc) See Data Book.
Some transition metals are essential for life (V, Cr, Mn, Fe, Co, Ni, Cu, Zn etc).
What holds a crystal lattice together?
Strong electrostatic attraction between positive and negative ions holds the lattice together.
Explain why ionic solid crystal lattices are hard and have high melting and boiling points.
The strong electrostatic attractions between positive and negative ions arranged in a three- dimensional lattice result in ionic solids being very hard and difficult to cut. A large amount of energy is required to overcome the strong attractions within the lattice and force the ions apart. The strong attractions between ions of opposite charges is also the reason ionic solids also have high melting and boiling points.
Explain why ionic crystal lattices are brittle.
When sufficient force is applied to an ionic solid to slide one layer of ions past another layer, the solid will break apart. This is due to
movement of ions within the lattice resulting in positive – positive and negative – negative repulsions occurring when ions of the same charge are forced near to one another.
Explain why ionic crystal lattices are electrically conductive when in molten state.
Ionic compounds do not conduct electricity in the solid state because there are no mobile charged particles available to transfer the current. When an ionic solid melts, the ions are no
longer fixed in a lattice but move freely through the liquid. An electric current is able to pass through the freely moving charged ions.
Explain why most ionic crystal lattices are soluble in water.
The electron distribution in a water molecule is not even, resulting in each water molecule having a positive end and a negative end. An ionic solid will dissolve in water when the attractions between the positive and negative ends of the water molecules and the positive and negative ions is greater than the attractions of the positive and negative ions for each other.
