Bonding, structure and the properties of matter Flashcards
Ionic bonding
What is ionic bonding?
The electrostatic attraction between positive and negative ions.
It forms between metals and non-metals
Ionic compounds
How are ionic compounds held together?
- Giant lattice
- Strong electrostatic forces
- Regular structure
Properties of ionic compounds
What are the properties of ionic compunds?
- High melting and boiling points
- Do not conduct electricity when solid (ions in fixed position)
- Conduct when molten or dissolved in a solution (ions can move)
Ionic compounds
How are ionic compounds formed? Explain in terms of MgO
Magnesium loses 2 electrons and becomes postively charged. Oxygen gains 2 electrons and becomes negatively charged. This forms an ionic bond.
Covalent bonding
What is covalent bonding?
The sharing of electrons between two non-metals
Properties of small molecules
Describe the structure and properties of simple covalent molecules
- Strong covalent bonds
- Weak intermolecular forces
- Low melting and boiling points
- Do not conduct electricity (no ions)
Metallic bonding
What is metallic bonding?
The strong forces of attraction between positively charged ions and negatively charged electrons
The three states of matter
How are the particles arranged in solids?
The particles are:
- packed tightly together
- vibrate in a fixed position
- have strong forces of attraction that require lots of energy to break
- high melting and boiling points
- cannot be compressed
The three states of matter
How are the particles arranged in liquids?
The particles are:
- still close together, but not as tightly packed
- able to move around
- weaker forces of attraction that require less energy to break
- lower melting and boiling points
- take the shape of their container
The three states of matter
How are the particles arranged in gases?
The particles are:
- very spread out
- move at different speeds in different directions
- very weak forces of attraction that require very little energy to break
- very low melting and boiling points
- take the shape of their container
- can be compressed easily
State symbols
What are the state symbols for solids, liquids and gases?
s
l
g
State symbols
What is an aqueous solution and what is the state symbol for it?
a solid dissolved in a liquid
aq
Polymers
What is a polymer?
A long chain of repeating molecules called monomers
Polymers
Why are polymers solids at room temperature?
The intermolecular forces between each of the polymer chains are relatively strong, because the molecules are larger compared to simple molecules. They require more energy to break, so they are solids at room temperature.
Giant covalent structures
Why are giant covalent structures different to simple molecules?
Giant covalent strctures are made up of thousands of atoms’
Diamond
Describe the structure and properties of diamond
- made up of carbon atoms
- each 1 atom is bonded to 4 others by strong covalent bonds - no delocalised electrons
- giant lattice structure
- a lot of energy is required to break the bonds : high melting and boiling points / hard
- cannot conduct electricity - no delocalised electrons
Graphite
Describe the structure and bonding in graphite
- made up of carbon atoms
- each 1 atom is bonded to 3 others by strong covalent bonds - 1 delocalised electron spare
- layers of hexagonal rings
- weak forces of attraction
- little energy is needed to break theses forces : layers can slide - soft and slippery
- high melting and boiling point - strong covalent bonds
- can conduct electricity - has delocalised electrons
Graphene and fullerenes
What is graphene?
Each layer of carbon atoms in graphite is called graphene. A sheet of graphene is only 1 atom thick
Graphene and fullerenes
Explain the structure, bonding and properties of graphene
- very thin and light
- high melting and boiling point (strong bonds)
- conducts electricity
Graphene and fullerenes
What are fullerenes?
Fullerenes are made up of carbon atoms bonded together by strong covalent bonds, forming hexagonal rings or sometimes pentagonal/heptagonal rings
Graphene and fullerenes
Why are fullerenes useful?
Fullerenes are hollow speared.
They can be used to cage other molecules, such as medicines. They can be used to deliver drugs into the body
Properties of metals and alloys
Describe the structure of metals
- positively charged ions
- regular arrangement
- giant lattice
- sea of delocalised electrons
- strong metallic bonds
Properties of metals and alloys
Describe the properties of metals
- high melting and boiling points (solid at rt)
- good conductors of electricity
- malleable
Metals as Conductors
Why are metals good conductors of electricity?
Metals have a sea of delocalised electrons that can move through the solution carrying a charge
Properties of metals and alloys
Explain what the difference is between pure metals and alloys
Pure metals are made up of only 1 metal atom e.g gold is made of gold atoms
Alloys are mixtures of different metal atoms (and sometimes carbon) e.g bronze is made of copper and tin atoms
Properties of metals and alloys
Explain why pure metals are soft
- atoms of the same size
- regular pattern
- the layers can easily slide over each other
Properties of metals and alloys
Explain why alloys are hard
- mixture of different sized metals
- distorts the regular arrangement
- hard for the layers to slide over each other
Size of particles and their properties
What is the size of coarse particles?
- diameter= between 1 x 10^-5 - 2.5 x 10^-6nm
- contains thousands (maybe millions) of atoms
- PM10 or dust
Size of particles and their properties
What is the size of fine particles?
- diameter= between 100-2500nm
- contain several thousand atoms
- PM2.5
Size of particles and their properties
What is the size of nanoparticles?
- diameter= between 1-100nm
- contain a few hundred atoms
Uses of nanoparticles
State the use of nanoparticles
- Medicine
- Electronics
- Deodrants
- Sun creams
Size of particles and their properties
Why do nanoparticles have properties different from those for the same materials in bulk?
High surface area to volume ratio
