c1 - atomic structure and the periodic table Flashcards
what is an element?
a substance made up of one atom only
what is a compound?
contain 2 or more different elements chemically combined together
what is a mixture?
different elements or compounds not
chemically combined together
what is a molecule?
A molecule has any elements chemically joined
what is filtration?
it separates an insoluble (does not dissolve) solid from a liquid
filtration method
- Put the filter paper into the filter funnel
- Pour the liquid in
- The silver chloride (solid) will be collected in the filter paper
- The water will pass through and will be collected in the beaker
what is crystallisation?
To separate an soluble (does dissolve) solid from a liquid
crystallisation method
- put a heatproof mat down and the Bunsen burner above it
- put the tripod on top and the gauze on the tripod.
- place the evaporating basin on top of the gauze
- pour the mixture into the evaporating basin and heat the Bunsen burner.
- Water will evaporate and the soluble will crystalise in the basin.
what is chromatography?
it is when you separate ink dyes based on solubility
chromatography method
- draw a pencil line on the filter paper and put ink colours on it
- place the filter paper into a beaker of water (the solvent) below the pencil line
- the solvent will rise up the paper revealing the soluble and insoluble colours.
mobile phase= solvent (moves up the paper)
stationary= paper (stays still)
why do we draw the starting pencil line?
If we drew the line in pen, the pen ink would move up the paper, it would smudge - mix in with the results.
what is simple distillation?
To separate a liquid from a solid if we want to keep the the liquid.
simple distillation method
- Heat the solution using a Bunsen burner
- As we heat the liquid it starts to evaporate into a vapour
- The vapor rises up the glass tube
- The vapor now passes into the condenser
(the condenser is kept cold by passing cold water through it) - The vapor now condenses into a liquid
- We collect the liquid in our beaker
result:
We are left with crystals of the solid in the flask and the liquid in the beaker
We can use simple distillation to produce drinking water from sea water HOWEVER a lot of energy is needed.
what is fractional distillation?
- To separate a mixture of different liquids
- These liquids must have different boiling points
fractional distillation method
- Heat the mixture using a Bunsen burner
- As we heat the liquids they start to evaporate but the one with the lower boiling point will evaporate more easily.
- When vapor rises (contains both liquid vapors) it enters the fractionating column
- They then condense and drip back into the flask
Note: If the 2 liquids have got very similar boiling points, then it is much harder to separate them. We might need to carry out several rounds of fractional distillation.
plum pudding model
JJ Thompson
a ball of positive charge with negative electrons scattered inside of it
who did the alpha scattering experiment
Rutherford and Marsden
results of alpha scattering experiment
the alpha
particles bounced
straight back - The centre of the
atom contains the most mass.
Some deflected slightly - The centre of the atom has a positive charge
Most of the alpha particles passed straight through - most of the atom is empty space
what did Niels Bohr discover?
Electrons orbit the nucleus at specific distances.
Orbits are now called energy levels.
what did James Chadwick discover?
The nucleus contains neutral particles called neutrons.
order of discovery for subatomic molecules
electrons
proton
neutron
radius of atom
0.1nm
1 x 10^10m
radius of nucleus
1 x 10^14m
charge of subatomic molecules
proton= +1
neutral= 0
electron= -1
relative mass of subatomic molecules
proton= 1
neutral= 1
electron= very small/0
overall charge is zero
how to work out proton neutron and electron
Protons : Bottom Number
Electrons : Bottom Number
Neutrons : Top - Bottom
what is an isotope
Isotopes are atoms of an element with same number or protons and electrons different numbers of neutrons
what does it mean if an atom has a negative charge
atom has gained electrons
what does it mean if an atom has a positive charge
atom has lost electrons
what does group number in periodic table tell you?
how many electrons are in the outer shell.
what did Dmitri Mendeleev do to the period table
He arranged all the elements in order of increasing
atomic weight (this was an exam question)
Grouped elements with similar properties
Left gaps for undiscovered elements
what is the modern periodic table
-arranged in atomic number
-has group zero
why is group zero inert (unreactive)
it has a full outer energy level so its stable.
what is the boiling point of group zero
- the boiling point increases
- gthis is because as you go down the group, the atoms get bigger (more electrons)
- so there are greater intermolecular forces that we need to overcome.
what happens to group 1 (alkali metals) metals as you go down the group
They get softer as you go down the group
Low melting and boiling point
All group 1 metals have 1 electron in their outer shell
This means they form 1+ ions
what happens to reactivity as you go down group 1 ?
Reactivity INCREASES as we go down the group
size of atom gets bigger
The outer electron gets further away from the nucleus
There is more shielding
As the atom gets bigger there is a weaker attraction
It is more easily LOST
what happens when group one reacts with oxygen
metal + oxygen –> metal oxide
appearance of when group one reacts with oxygen
lithium + water
lithium floats
It fizzes steadily and becomes smaller until it eventually disappears
Sodium + water
Sodium melts to form a ball that moves around on the surface
It fizzes rapidly, and the hydrogen produced may burn with an orange flame before the sodium disappears
Potassium + water
Very violent reaction
The metal melts and floats
It moves around very quickly on the surface of the water
The hydrogen ignites instantly
The metal is also set on fire, with sparks and a lilac flame
Rubidium/Caesium + water
Explodes with sparks
Violent explosions due to the rapid production of heat and hydrogen
what is produced when alkali metal reacts with water
alkali + metal –> alkali metal hydroxide + hydrogen
what happens to group 7 (halogens) as you go down the group
Have 7 electrons in their outer energy level/shell
Are all non-metals
Group 7 elements form molecules: 2 atoms joint by a covalent bond e.g. F2
Form 1- ion and the name ends in IDE
e.g. Fluorine - FluoRIDE
what happens to reactivity of group 7
As you go down group 7
size of atom gets bigger
The outer electron gets further away from the nucleus
There is more shielding
As the atom gets bigger there is a weaker attraction
It is more difficult to GAIN an electron
