C2 Flashcards
What is an isotope?
Atoms of the same element with a different number of neutrons
What kind of bonding is it where electrons are transferred?
Ionic
What is the calculation for rate of reaction?
- Change is mass / time
- Volume of gas produced / time
- Decrease in volume / time
What is collision theory?
When particles collide and react
How does the reaction happen? (collision theory)
- Reactions only happen if the particles collide with enough energy.
- The minimum amount of energy needed by the particles to react is called the activation energy
- Without the activation energy the reaction cant happen
What 5 factors affect the rate of reaction?
- Temperature
- Concentration
- Pressure
- Surface area
- A catalyst
What are the subatomic particles?
is -Electron (negative charge, negligible mass)
- Proton (positive charge, mass of 1)
- Neutron (no charge, mass of 1)
Describe ionic bonding
When to atoms lose or gain electrons in order to have full outer shell and become ions
What is covalent bonding?
Where atoms share electrons in order to have a full outer shell
What are the properties of ionic compounds?
- Lattice properties- ions in a regular pattern in alternate positions
- High melting point due to a strong electrostatic attraction (very strong attractions between positive and negative ions)
- Doesn’t conduct electricity when solid because the ions aren’t free to move
- Conducts electricity when dissolved or melted as the ions are free to move
What is the structure of a metallic structure?
Lattice
Why do metallic structures have a high melting point?
The positive ions and negative electrons are very strongly attracted.
Are metallic structures malleable?
Yes - the layers of the metal atoms can slide over each other easily
What is the structure of ionic structures?
Lattice
Why do ionic structures have a high melting points?
The positive and negative ions are very strongly attracted
What atoms make up ionic structures?
Metal and non metals
Do ionic structures conduct electricity when solid?
No, when solid the ions can’t move
Do ionic structures conduct electricity when dissolved or melted?
Yes, high electrical conductivity as the ions can move and transfer electrons
What kind of structures do giant covalent structures have?
Lattice
Do giant covalent structure have a high or low melting point?
They have a high melting point as there are millions of very strong covalent bonds that have to be broken
What kind of structure do simple covalent structures have?
Molecules
Why do simple covalent bonds have low melting points?
They have weak intermolecular forces which are easily broken
What types of elements create simple covalent structures?
non-metals
Why do simple covalent structures have low electrical conductivity?
Because there are no free ions or electrons
Why are metallic structures such good conductors?
They have delocalised electrons which move and carry the electrical current throughout the structure
What element are diamond and graphite made of?
Carbon
How many covalent bonds does each atom have in diamond?
4
What is another way of saying giant covalent structure?
Macromolecule
Why is diamond so hard?
Lots of energy is needed to break he millions of covalent bonds in in, therefore it also has a very high melting point
Why doesn’t diamond conduct electricity?
Because there are no free moving electrons or ions
How many covalent bonds does each carbon atom have in graphite?
3
Why does graphite have a high melting point?
There are strong covalent bonds between the molecules
Why is graphite soft and slippery?
The bonds have weak forces of attraction so they can slide past each other easily
How can graphite conduct electricity?
1 out of 4 electrons in the outer shell are delocalised
What kinds of chains do HDPE’s have?
Long unbranched chains which allow hem to be close together and therefore high density
Can HDPE’s be remoulded?
Yes, they can be softened and remoulded when heated
What kinds of chains do LDPE’s have?
Branched chains therefore they cant be packed closely together and therefore low density
Can LDPE’s be softened?
Yes they can be softened and remoulded very easily when heated
What kinds of chains do thermosoftening polymers have?
Long unbranched chains, so when they’re heated they can slide over each other
Can thermosoftening be remoulded?
Yes they can remoulded and once cool they can be reheated and remoulded
Example of thermossoftening polymers
Polyethene in carrier bags
What kinds of chains do thermosetting polymers have?
Long chains that cross link to other long chains preventing them from sliding over eachother
Can thermosetting polymers be remouled?
No, once cool they cannot be remoulded
Examples of thermosetting polymers
Rubber in car tyres
What is the relative formula mass (Ar or Mr) of a substance in grams also known as?
A mole of the substance
What does one mole of an atom contain no matter the element
6x10^23
Why might you not get 100% yield?
- A reaction might be reversible
- Some product may be lost during the process eg. spillages
- Unwanted reactions might take place to make different products
What is the empirical formula?
The simplest ratio of the atom of each element present in the compound
What is the molecular formula?
The actual number of the atoms of each element in the compound
How do you find an rf value? (chromatography)
distance substances moved / distance solvent moved
What is the pH of an acid?
pH 1 to 6
What are ammonium salts used for?
Fertilisers
What does the symbol aq stand for
Aqueous (dissolved in solution)
What ions form when you add acid to water?
H+ ions
What salt is made when magnesium reacts with hydrochloric acid?
Magnesium chloride
What are the products of the reaction between an acid and a metal?
- Salt
- Hydrogen
What are the products of the reaction between an acid and an alkali
- Salt
- Water
What is the pH of an alkali?
pH8 to 14
What ions are formed when a base is dissolved in water?
OH- ions
