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Paper 1 - Atomic Structure and the Periodic Table - Coggle Diagram
Paper 1 - Atomic Structure and the Periodic Table
Atoms, Elements, Compounds and Mixtures
Atoms, Elements and Compounds
Atoms
All substances are made of Atoms
Atoms make up the smallest part of an element that can exist
Elements
One type of atom in an element
Compounds
Compounds contains atoms of 2 or more elements
Most substances are compounds
Only able to be split into its original elements by electrolysis and chemical reactions
Equations
Total mass of reactants = total mass of products
Because you can't lose or gain atoms
reactants -----> products
Separating Mixtures
2 or more elements or compounds that aren't chemically combined and still have their own properties
e.g. iron and sulfur mixture iron is still magnetic and sulfur is still yellow
Can be separated by physical processes
Methods of separating mixtures
Filtration
Separates soluble soluble from insoluble solids
Crystallization
Used to obtain a soluble solid from a solution e.g. salt crystals can be obtained from a solution of salty water
the mixture is gently warmed
the water evaporates leaving crystals of pure salt
Simple Distillation
Used to obtain a solvent from a solution
Fractional Distillation
Used to separate mixtures of components with different boiling points
Chromatography
Separates different soluble coloured components of a mixture
Atoms and the Periodic Table
Scientific Models of the Atom
Rutherford, looked at resulted of above and concluded that a positive charge of an atom must be concentrated in a very small area and named it the 'nucleus' and created the 'nuclear model of the atom'
Geiger and Marsden bombarded a thin sheet of gold with alpha particles, most positively charged alpha particles passed straight through the atoms and a tiny number were deflected back to the source
1898 Thompson, discovered electrons - 'Plum Pudding Model' thought it contained negative electrons surrounded by a sea of positive charge
Bohr electrons must orbit the nucleus at specific distances or would spiral inwards, later experiments showed the nucleus is made of smaller particles, some are positively charged (protons) and some a no charge (neutrons)
beginning, thought atoms couldn't be divided into simpler particles
Subatomic Particles
Number of neutron = mass number - atomic number
same number of protons and electrons
number of protons = atomic number
most of the mass of an atom is in the nucleus
Isotopes and Ions
Isotope - same number of protons but different number of neutrons therefore the same atomic number but different mass number
atoms gain/loose electrons to become ions
metal atoms loose atoms to from positive ions
non-metal atoms gain atoms to from negative ions
Electron Configuration
electrons in an atom occupy the lowest available shell/ energy level
1st 20 elements the first shell can only hold a max number of 2 elecetrons
next 2 shells can each hold a maximum of 8 electrons
electron configuration of an atom shows how the electrons are arranged around the nucleus in shells
The Periodic Table
Group 0
Noble Gasses
Very Stable/Unreactive
Non-metals
Full Outer Shell
Group 1
1 Electron in their Outer Shell
Alkali Metals
Get more reactive the more you go down - easier to lose outer electron
Low Boiling/Melting Point
Stored in oil - They react with oxygen and water (moisture in the air)
When it reacts with water, you get a metal hydroxide + hydrogen
Low Density
Alkali Metal reacting with non-metal = ionic compound
this is when metal atom loses 1 electron to form a metal ion with a positive charge
The Development of the Periodic Table
John Newlands
Arranged in order of atomic weight - created patterns
Only 63 elements were known
Dimitri Mendeleev
Reordered some elements
1869
Left gaps for undiscovered elements
The elements were placed in vertical columns (groups) with similar properties
Used the PT to predicted the properties of new elements
When the subatomic particles were later discovered he realized he had organised the elements in order of increasing atomic number (Number of Protons)
Group 7
7 Electrons in their Outer Shell
Halogens
Halogens react with metals to form an ionic salt
When this happens the Halogen atom gains an electron to form Halide ion with a negative charge
Get less reactive the more you go down - Harder to gain a outer electron
A more reactive halogen will displace a less reactive halogen from an aqueous solution of its salt
Chlorine + Potassium Bromide -----> Potassium Chloride + Bromine