Ionic substances are made of oppositely charged ions arranged in a 3D crystal lattice. There is a strong electrostatic force of attraction between the oppositely charged ions.
Because there is a strong electrostatic force of attraction between the charged ions, a high amount of energy will be required to overcome these forces of attraction. This gives ionic compounds a high melting & boiling point.
When force is applied on the crystal lattice, the lattice can shaters if two like-charges come across each other, causing them to repel and break the structure
Oppositely charged ions get attracted to the partial negative and postive ends of the polar water molecule. Solute-solvent attractions are strong enough to overcome solute-solute and solvent-solvent attractions.
Electricity is the flow of charge. In ionic bonds, this is not electrons it is the ions. Ionic substances are able to conduct electricity in liquid/molten/aqueous states as the charges are free to move around and carry charge.
melting/boiling point: high
malleable: no
ductile: no
brittle: yes
electrically conductive: only when liquid
thermally conductive: no*
* - for the exam they want us to say no but in reality it's much more complicated idk
Metal cations (positive) are electrically attracted to the 'sea' of delocalised electrons, forming a non-directional metallic bond.
A lot of external force is needed to overcome the strong metallic bond to wear metal cations away from the structure.
The closely packed ions allow efficient collision between metal ions. Also the free-moving electrons gain Ek and enchance the collsion to transfer heat.
The metallic bond is non-directional, so when external forces are applied the layers of metal ions can slide across each other without breaking the bond.
melting/boiling point: high malleable: yes ductile: yes brittle: no electrically conductive: yes thermally conductive: yes
Atoms are covalently bonded (able to share electrons) with each other to form a molecule. These molecules interact with each other via weak intermolecular forces.
Only a small amount of heat energy is needed to overcome the weak intermolecular forces.
The distance between molecules is far away. The makes the collisions between particles very inefficient and thus not allowing charge or heat to transfer. Because therea are weak intermolecular bonds between molewcules, it will require less heat energy to break them.
The electrostatic force holding the ion in substances like NaCl (ionic substances) will be overcome in water due to fact that solute-solvent bonds overcome solute-solute and solvent-solvent bonds.
melting/boiling point: low
malleable: no
ductile: no
brittle: sometimes (doesnt matter lol)
electrically conductive: no
thermally conductive: no
talking about molecular substances, carbon chains also exist and will likely show up so here's my chance to yap about them.
Carbon chains are awesome! But to be more specific, carbon chains are pretty much just carbon atoms bonding with other carbon atoms within a molecule. Carbon can bond in different way and depending on these ways that it's bonded, itwill act differently. This is called an allotrope. For example take diamonds and graphite. Both are 3D crystal lattices made entirely out of carbon atoms but act very different due to how the atoms are bonded.
Diamonds are one of the toughest materials, this is due to how the carbon atoms are bonded with each other inside the structure. The carbon atoms in diamonds are covalently bonded in a tetrahedral arrangement. Each carbon atom is bonded to 4 other carbon atoms (the same amount as it has valance electrons) allowing each atom to be locked into place by the other atom's bonds
Graphite, however is quite different. Each carbon atom in graphite is bonded to 3 other carbon atoms, with an extra valance electron free and not bonded to another atom (probably not relevant in the test but it's fun to know). Graphite is made out of multiple layers of the carbon atoms arranged in hexagonal formation. These are called graphene. Because the bonds between layers of graphene are weak, they can easily side past each other. This also means that the bonds between layers of graphene are easily broken. Because graphite has each carbon atom bonded to 3 other atoms, it has a valance electron not shared in the covalent bonds, meaning it is delocalised allowing it to be electrically conductive and able to transfer charge throughout the graphite. Because the layers of atoms can slide past each other due to weak intermolecular forces, the graphite will leave marks on the paper as a lubricant.
The physical properties of iron make it a perfect candidate for beating the shit out of people. This is due to iron’s density and malleability. Iron is a metallic substance, meaning that it forms metallic bonds via the attractive forces between the positively charged iron ions and the negatively charged delocalised sea of electrons. The reason why iron is malleable is due to these metallic bonds being nondirectional, meaning the bonds do not break when force is applied. The iron being dense is due to the strong metallic bonds holding the iron ions close together as well as iron being a relatively bigger atom, resulting in more mass per volume of iron.
These physical properties are advantageous for beating the shit out of people as the density of iron makes the force of swinging it at someone’s face bigger, meaning that the impact will be harder. The malleability of iron allows it to be shaped into whatever the user wants it to be for maximum beating-the-shit-out-of-people power. Thus, iron is suitable as a material for creating a weapon to beat the shit out of people.