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ATOMS AND HOW TO SEPARATE MIXTURES (HISTORY OF THE ATOM (460 BC Democritus…
ATOMS AND HOW TO SEPARATE MIXTURES
DISTILLATION
STEP 1: the mixture is heated until it has reached its lowest boiling point. The liquid then turns into vapour and fills the flask then travels to the condenser.
STEP 2: cool water surrounds the condenser. The vapour then condenses back into the liquid.
STEP 3: the pure liquid then leaves the condenser and is collected in a conical flask.
FILTRATION
This process removes an insoluble solute from a liquid.
The solute left in the filter paper is referred to as the FILTRATE
CRYSTALLISATION
It removes soluble substances from a liquid which it is dissolved into.
This happens by forming a saturated solution, and then allowing the saturated crystals to slowly grow.
SIMPLE DISTILLATION
Used to separate a mixture of two or more liquids with different boiling points
FRACTIONAL DISTILLATION
Used to separate a mixture of two or more liquids with more similar boiling points, so they would be unable to be separated by simple distillation.
CHROMOTOGRAPHY
Used to separate a mixture of inks or dyes
HISTORY OF THE ATOM
460 BC Democritus and his mentor came up with the idea of atomic theory. He predicted that if you continually cut something in half you would end up with a tiny particle that could not be divided any further.
1766-1844 John Dalton suggested all substances were made of small hard spheres called atoms- he believed that a single element was made up of one type of atom, and different elements had different types of atoms
JJ Thomson experimented with gases at low pressure and discovered electrons. He created the PLUM PUDDING MODEL.
1913 Niels Bohr excited electrons by heating them up. He noticed that the elements only emitted light of certain wavelengths. He hypothesised electrons could only orbit the nucleus at set distances. He created BOHR'S MODEL OF THE ATOM.
1908-1913 Rutherford fired alpha particles at gold leaf. Some particles were deflected; others bounced back- this is evidence for a positively charged nucleus. He created the NUCLEAR MODEL OF THE ATOM.
PROTONS
have a mass = 1
they also have a positive charge
NEUTRONS
have a mass = 1
they have a neutral charge
ELECTRONS
has a mass = 0
they have a negative charge
their masses are relative atomic masses
MASS NUMBER = protons + neutrons
ATOMIC NUMBER: protons = electrons
ISOTOPES HAVE THE SAME ATOMIC NUMBER BUT A DIFFERENT MASS NUMBER
ISOTOPES - can have different physical properties. However, they always have the SAME chemical properties as only the ELECTRON arrangement effects an element's reactivity.
Atoms can LOSE or GAIN electrons to form IONS.
IF THE ELEMENT LOSES AN ELECTRON IT BECOMES A CATION.
IF THE ELEMENT GAINS AN ELECTRON IT BECOMES AN ANION.
The nucleus contains PROTONS and NEUTRONS
Electrons are arranged in ENERGY LEVELS around the nucleus
ATOMS HAVE NO OVERALL CHARGE AS THE NUMBER OF PROTONS AND ELECTRONS ARE EQUAL SO THEY CANCEL EACH OTHER OUT