Paper 3 : C1 + C2 + C3 + C7 Flashcards
What is an isotope?
Atom with the same atomic number and different mass number
How did Geiger and Marsden contribute to ideas about the structure of the atom?
Fired alpha particles at gold
Some alpha particles rebounded
Led to the idea that atoms have a nucleus
How did JJ Thompson contribute to atomic theory?
He discovered the electron
How did Bohr contribute to atomic theory?
He suggested that electrons occupy energy levels
Describe metallic bonding
Attraction between positive metal cations
And delocalised electrons
Why do metals conduct electricity?
They have delocalised electrons
Why do ionic compounds conduct electricity when molten or in solution but not as a solid?
In a solid ions cannot move
When dissolved or molten the ions can move
Why do ionic compounds have high melting points?
Strong attraction between oppositely charged ions
Why do metals have high melting points?
Strong attraction between positive ions and delocalised electrons
Why can non-cross linked polymers be stretched easily?
Weak intermolecular forces
Polymer molecules can slide over each other
Why do cross-linked polymers have high melting points?
Strong crosslinks between the polymer molecules
Why is diamond used in cutting tools?
It is hard and it has a high melting point
Why is graphite slippery?
Weak bonds between the layers
Layers can slide over each other
Why is diamond used in jewellery?
Lustrous and transparent
Why do giant covalent compounds have high melting points?
Strong covalent bonds
Need lots of energy to break the bonds
What is an allotrope?
Different structures of the same element
Why does graphite conduct electricity?
It has delocalised electrons
Why is graphite used in pencils?
Layers can slide over each other
Black so can be seen on the paper
Why does graphite / diamond have a high melting point?
Many covalent bonds
Lots of energy needed to break the bonds
Strong intermolecular forces
Why do simple covalent compounds have low melting and boiling points?
Weak forces between molecules
What is a spectator ion?
An ion that is in the solution both at the start and the end of the reaction
Explain what happens during neutralisation?
Hydrogen ions react with hydroxide ions to make water
What makes a reaction be exothermic?
Bond making gives out energy
Bonds in the products are stronger than those in the reactants
So more energy is given out than taken in
What makes a reaction be endothermic?
Bond breaking takes in energy
Bonds in the products are weaker than those in the reactants
So more energy is given out than taken in
What is reduction?
Gain of electrons
What is oxidation?
Loss of electrons
What is the difference between a strong and a weak acid?
Strong acids completely dissociate
Weak acids only partially dissociate
Why do weak acids react more slowly than strong acids?
Weak acids dissociate less so there is a lower concentration of H+ ions
This gives a lower frequency of collisions
What is a redox reaction?
A reaction that involves both oxidation and reduction
