atomic structure and the periodic table Flashcards
what is an atom?
the smallest part of an element that can exist
what is a compound?
pure substance made from two or more elements chemically combined
what is a mixture?
consist of two or more elements/compounds not chemically combined
rutherford experiement
1911
alpha particles fired at thin gold foil
- most went through= atom mostly empty space
- some slightly deflected= charged centre
- few deflected by >90= central mass
dalton
1800
tiny spheres that cannot be divided
jj thompson
1897
plum pudding
overal charge- neutral
Positively charged mass with electrons embedded
rutherford
1913
nuclear model
positive nucleus, with cloud of electrons around
bohr
1913
energy shells
chadwick
1932
neutrons
how to calculate relative atomic mass
(%isotope x mass A) + (%isotope x mass B)/100
x+x dead
why is the periodic table called periodic table?
because similiar properties occur at regular intervals
how was the periodic table arranged before?
by atomic weight
1869
mendeleev
how did mendeleev arrange the periodic table
by atomic weight but not as strictly to allow same properties in groups
left gaps
why did mendeleev leave gaps?
and how did he predict elements?
- for undiscovered elements
- by using properties and trends in th group
what elements forms positive ions?
metals
what elements forms negative ions
non-metals
properties of metals and why
- high melting & boiling points- strong lattice structure- electrostatic attraction
- good conductors of heat & electricity- delocalised electrons
- solids at room temperature (except mercury!)- strong electrostatic forces
- shiny
- malleable- layers of ions slide over
- ductile
properties of non-metals and why
- low melting and boiling points- weak intermolecular forces- covalent
- NOT good conductors of heat & electricity- no free electrons
- gases at room temp- weak intermolecular bonds
- dull
- brittle- weak bonds
what is group 0
noble gases- full outer shells
properties of group 0 (3)
- colourless gases
- inert
- non- flammable
trends of reactivity and boiliing/melting points of group 0 going DOWN
- reativity- NON-REACTIVE
- b/m- INCREASE
what is group 1
alkali metals- 1 outer electron
propertes of group 1 (4)
- soft
- low density
- low melting/boiling points
- more reactive
trends of reactivity and boiliing/melting points of group 1 going DOWN
why
- reactivity INcreases- electron weaker forces of attraction to loose
- b/m- DEcrease- weaker attractive forces
Group 1
- reaction with water
- reaction with oxygen
- reaction with chlorine
WOC!?
- water- VIGEROUSLY -» hydroxide + water (alkaline solution)
- oxygen -» metal oxide
- chlorine -» metal chlorides
lithium
sodium
potassium
WOC
lithium- W fizzes O red flame C white powder settles
sodium- W rapid fizz O orange flame C bright yellow flame-> white powder
potassium- W sparks lilac flame O lilac flame C more vigerous^
lithired sodiorange potassialic
what is group 7
halogens
properties of group 7
- dangerous
- diatomic- covalent
- halide - ion
trends of reactivity and boiliing/melting points of group 7 going DOWN
why
- reactivity- DEcrease- weaker attractive forces to attract electron
- b/m- INcrease- increasing intermolecular forces- more energy
group 7- state and appearance at room temp & colour in solution
fluorine
chlorine
bromine
iodine
fluorine- poisonous yellow gas
chlorine- poisonous green gas- pale green/colourless
bromine- red/brown volitile liquid- orange
iodine- grey solid- purple vapour- dark brown
colour change in displacement,
fluorine- flo- yellLOW
chlorije- what kills u- chlorine- green green grass, better throw part day that i die- in solution, diluted
bromine- BRick red- diluted brOmine
iodine- boring different, magic, vapour- not expected- iodine solution- starch
properties of transition metals
- form coloured compounds
- have ions with different charged
- not as reactive as 1
- dense
- good conductors
uses of transition metals
- catalysts- bc of range of oxidation states
- medicine
- dyes & paints
