Atoms, bonding and moles Flashcards
What is filtration?
A method to separate insoluble molecules from each other by merely passing them through a mesh (filtration paper) that only one molecule can fit through
What is crystallisation
A method to separate soluble materials from each other, by using a water bath to evaporate the liquid to leave just the dissolved solid in the basin
what is distillation?
Crystallisation but gaining the evaporated solvent
A solution is boiled and the vapour given off is channelled through a condenser (a glass tube with cold water flowing through it to condense the vapour) and the liquid vapour now drips into a beaker
What is fractional distillation?
Where a mixture is boiled and condensed, however to separate the mixture they have a column to separate the different boiling points
The solution is pumped in and heated, evaporating it. The vapours rise up the tube, getting further away from the heat and cooling down at different points depending on their boiling points and getting siphoned off, separating the mixture
what is chromotography?
A method to separate and identify substances from solutions with paper.
A capillary tube is used to dab a bit of solution on the bottom of the paper.
The paper is then placed in water
Water soaks up the paper and runs with the dissolved solution and depending on how far the solution travels shows it’s solubility
What is the gold foil experiment and what did it discover?
Alpha particles were shot at a thin piece of gold foil and were expected to pass right through
The occasional alpha particle was reflected back, showing it had hit something
This proved that the nucleus was a thing
What is an isotope?
The same element with a different number of neutrons
Who was Mendeleev and what did he do?
He rearranged the periodic table in order of atomic weights and left space for other elements that had not been discovered but fit the gaps
What is group 0 of the periodic table called?
The noble gases
What is group 1 of the periodic table called?
The alkali metals
What are the properties of alkali metals?
Very reactive
their reactivity increases the further down you go
Low density
What is group 7 of the periodic?
The halogens
What are properties of the halogens?
They’re toxic
Low melting and boiling points
Poor conductors
What are the differences in reactivity between the halogens and the alkali metals
The alkali metals get more reactive as you go down the group
Halogens get less reactive as you go down the group
What are properties of transition metals?
Shiny Good conductors Hard and strong High densities High melting points
What is a compound?
Two or more elements that are chemically combined
Why are noble gases not reactive?
They have a stable amount of electrons
What is covalent bonding?
When electrons are shared between elements to get a full outer shell (Mostly between a non-metal and non-metal)
What is ionic bonding?
When electrons are given to other elements to create a full outer shell, creating ions
Usually in a metal and non-metal reaction
How do you draw an ion in a diagram?
The atom with a bracket around it and it’s charge at the top
What structure does ionic bonding create?
A giant structure or giant lattice
What does the group number of an element give?
The number of electrons in the outer shell
Is an ionic lattice strong?
Yes, as they are tightly packed and the ions have strong electrostatic bonds of attraction towards each other
Why can a solid ion compound not conduct electricity but a molten one can?
The charged ions can’t move around in a solid, but in a liquid they can so it can produce a current
Are covalent bonds strong?
Yes, as the electrons are stuck between two protons, meaning they are pulling in both ways
How do you draw a covalent bond on a diagram?
Like a venn diagram with the shared electrons in the intersection
Is the intermolecular forces in a covalent structure strong?
No, although the covalent bond itself is
Do intermolecular forces increase or decrease as particles get bigger?
Increases, so larger molecules have higher melting and boiling points
What is a polymer?
A chain of repeating units
How can you raw a polymer?
A single unit with brackets around it and the number of repeats at the bottom
Do covalent bonds conduct electricity?
No as there is no overall charge
What structure is diamond?
A giant covalent structure
What are properties of giant covalent structures?
high melting point and boiling point
insoluble in water
Hard and don’t conduct electricity (apart from graphite)
Why can graphite layers slide over each other?
The molecules are arranged in layers with no covalent bonds, only weak intermolecular forces
