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Atomic Theory - Coggle Diagram
Atomic Theory
Scientific Models
Nuclear Model
1911
Ernest Rutherford
atom mass mostly contained small positive nucleus
surrounded by large space
occupied by negative electrons
Planetary Model
1913
Niels Bohr
Modified Rutherford's model
Proposed electrons travel
pathways around nucleus called orbits
explained why different elements
produce different coloured light when heated
due to electrons moving from higher to lower orbits
Dynamide Model
1904
Phillip Lenard
atoms mostly empty spaces
filled
fast moving 'dynamides'
Dynamides
neutrally charged particles
made up of heavy positive particle stuck to a light negative particle
Plum pudding model
Year: 1904
Joseph John Thompson
discovered
negative charge
electron
must be a positive charge
in an atom
make an atom charge neutral
atom is round ball
positive charge
negatively charged electrons
embedded
Planetary model with neutrons
James Chadwick
1932
Nucleus not a mass of positive charge
cluster of positively charged protons and neutrons
Solid-ball model
460-370 BCE
Suggested by Greek Philosopher Democritus
first used the term 'atomos' means invisible
matter was not continuous
but made up of tiny, solid and unbreakable particles
Electron cloud model
1932-today
Position of an electron in an atom
never exactly known
Impossible for electrons to revolve around the nucleus in specific orbits
Continuum Model
Early BCE
All matter made up of 4 fundamental elements
Air
Fire
Earth
Water
Predicted
no matter how many times you 1/2 a piece of matter
it can always be broken down into smaller pieces
First hand investigation
Module 1
burning a candle in closed container
observations
qualitative
flame extinguished
water level rose
change in pressure
quantitative
time to extinguish
height of water level
combustion reactions
Paraffin wax (C-H)
fuel + oxygen --> products --> (ENERGY)
Long standing assumption
Phlogiston theory
materials that burn contain phlogiston
responsible for making it burn
What scientific investigation?
Characteristics of acids and bases
qualitative
acid/base indicator
universal indicator (colour change)
quantitative
pH meter
more accurate
pH scale
ranges from 0-14
pH 0-6 acids
corrosive
increase hydrogen (H)
pH 8-14 bases
caustic
increase Hydroxide (OH)
reflects the concentration of hydrogen ions (atoms in solution)
Module 2
Reactions with carbonate (CO3)
carbonate with acid
Observing Patterns
Elements and their properties
metals
good conductors
malleable (easily bent)
Lustre (shine)
Ductile (stretched into wire)
usually solid at room temperature
Usually high melting points
non metals
dull
poor conductors (insulator)
brittle
not always solids
Metaloids
Dmitri Mendeleev (1834-1907)
drafted first modern periodic table
grouping element s with similar properties in columns
left gaps
reactivity
Peer review and collaboration
Unstable isotopes
Radioisotope
carbon -14 nucleus
8 neutrons (neutral)
6 protons (+)
Carbon -12 nucleus
6 protons (+)
6 neutons
Element with unstable nucleus
radioactive decay
stable
Nuclear radiation
half life
time taken for 1/2 of a radioisotope to decay
irregular pattern
Difficult to identify pattern
long half life
e.g. Carbon -14, half life of 5730 years
