C2 - Bonding, Structure and Properties of Matter Flashcards
(35 cards)
What are positive and negative ions called?
Positive - Cation
Negative - Anion
What is an ionic bond?
When a metal and non-metal react together, the metal atom loses electron to form a cation and the non-metal ion gains electrons to form an anion. These two ions are oppositely charged so they are strongly attracted to each other by electrostatic forces of attraction. This is called an ionic bond.
How do you show ionic bonds?
Dot and cross diagram.
What structure do ionic compounds have?
Giant Lattice Structure- the ions form a closely packed regular lattice arrangement where there are strong electrostatic forces of attraction between oppositely charged ions in all directions in the lattice.
Why do ionic compounds have certain properties?
- High MP/BP: There are many strong, electrostatic forces of attraction between the ions. It takes lots of energy to overcome these forces.
- Conduct electricity: When they’re solid, the ions are held in place, so they can’t move throughout the structure. However, when they are melted or dissolved in water, the ions are free to move throughout the structure or solution, so they’ll carry electrical charge.
What is a covalent bond?
When non-metal atoms bond together, they share pairs of electrons. This is called a covalent bond.
Why are covalent bonds strong?
The positive nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces of attraction.
Evaluate the ways of displaying covalent bonds.
Dot and cross:
+ Show which atoms the electrons come from
- Don’t show the relative sizes of the atoms
- Don’t show how the atoms are arranged in space
Displayed formula:
+ Show how atoms are connected in large molecules
- Don’t show the 3D structure of the molecule
- Don’t show which atoms the electrons in the covalent bond have come from
3D Model:
+ Shows the sizes of the atoms
+ Shows the covalent bonds
+ Shows their arrangement in space next to each other
- Can get confusing when dealing with larger molecules
- Don’t show where the electrons in the covalent bonds have come from
What is a simple molecular substance?
They are made up of molecules containing a few atoms bonded together by covalent bonds.
What are the properties of simple molecular structures?
- Strong covalent bonds.
- Weak intermolecular forces.
- Low melting and boiling point because only the intermolecular forces need to be overcome, not the bonds.
- Gases and liquids at room temperature.
- Don’t conduct electricity because they aren’t charged, so there are no free electrons or ions.
What is a polymer?
A long chain of repeating units.
What are all atoms in a polymer joined by?
Strong covalent bonds.
How do you find the molecular formula of a polymer?
Write down the molecular formula of the repeating unit inside the brackets and put an n outside.
Example: Polyethene - (C2H2)n
Why are polymers solids at room temperature?
Unlike simple covalent molecules, the intermolecular forces between polymer molecules are large, so they require more energy to break them.
What are the properties of giant covalent structures?
- Strong covalent bonds.
- High melting and boiling points as lots of energy is needed to break the strong covalent bonds between atoms.
- Don’t conduct electricity as there are no charged particles.
What is an allotrope?
Different structural forms of the same element in the same physical state.
What are the properties of diamond?
- Each carbon arm has four covalent bonds, so it is very hard.
- It has strong covalent binds which take lots of energy to break, so it has a very high melting point.
- There are no free electrons or ions, so it doesn’t conduct electricity.
What are the properties of graphite?
- Each carbon atom is bonded to three other carbon atoms, creating hexagonal layers of carbon atoms.
- There are no covalent bonds between the layers, so they’re held together weakly. This means they’re free to move over each other, making graphite soft and slipper so it’s ideal as a lubricating material.
- Covalent binds require lots of energy to break, so graphite has a high melting point.
- Since one carbon atom is only bonded to three other atoms, there is one delocalised electron that can move throughout the structure. Therefore, graphite conducts electricity and thermal energy.
What is graphene and what are it’s properties?
- It is one layer of graphite (carbon atoms joined together in hexagons).
- It is one atom thick, so it is 2D.
- It has lots of strong covalent bonds and is very light, so it can be added to composite materials to make them stronger without adding much weight.
- They also conduct electricity.
What is a fullerene?
Molecules of carbon shaped like closed tubes or hollow spheres.
What can fullerenes be used for?
- They can deliver a drug into the body as they can trap molecules inside of them.
- They are great industrial catalysts because of their large surface area.
- They are good lubricants.
- They can form nanotubes.
Describe metallic bonding.
1) Metals have a giant structure.
2) The delocalised electrons in the outer shell of a metal atom have strong electrostatic forces of attraction with the positive metal ions.
3) These forces hold the atoms together in a regular structure and are known as metallic bonding. Metallic bonding is very strong.
What are the properties of metals?
- They have a high melting point and are generally a solid at room temperature because the electrostatic forces between the metals and the delocalised sea of electrons are very strong, so they need lots of energy to be broken.
- They are good conductors of electricity and heat because the delocalised electrons can carry electric charge and thermal energy through the whole structure.
- They are malleable because layers of atoms in a metal can slide over each other.
What is an alloy?
A mixture of two or more metals or a metal and another element.
