S3.1 Periodic Table Flashcards
how atomic radii in noble gases was measured
freezing = close as possible = measure
periodicity
repeating pattern of a property
periodicity trends
- ionisation energy
- electron affinity
- electronegativity
- atomic size/radii
- reactivity
Metal properties
- malleable
- lustrous
- high m.p
- high thermal & electrical conductivity
- tendency to losse e-
Non metal properties
- brittle
- dull
- low melting points
- low conductivity
- tendency to gain electrons
Metalloid properties
- both metal & non metal
- high m.p
- intermediate conductivity
- lustrous
- brittle
Atomic size trend
measured as covalent radius in half the distance between nuclei
* size decreases going across period
* size increases going down group
Atomic size trend - Period
- decreases
- nuclear charge increases
- larger attractive force between shell and nucleus
- pulls electrons closer => smaller size
Ionisation trend - Group
- decreases
- shielding effect = hinders attraction between nucleus & shell
- easier to lose e-
Atomic size trend - Group
- increases
- shells increase
- less attraction
- shielding effect
Ionisation trend - Period
- increases
- charge increases = larger attraction
- more difficult to lose e-
Ionic Radius
based on nuclear charge to outer electron ratio
When answering periodicity questions
SANDI
shielding
attraction
nuclear charge
distance
ionisation
Electron affinity
the energy change when 1 mole of electrons is added to 1 mole of gaseous atoms to form 1 mole of gaseous ions
Electronegativity Trend - Period
- increases
- nuclear charge increases = greater attractive force
Electronegativity Trend - Group
- decreases
- shielding/screening hinders electron attraction
Sodium + Water
NaOH + H2
* vigurously
* melts into spehre
* whizzes on surface
Lithium + water
LiOH + H2
* effervescene
* floats
* slowly
Potassium + Water
- KOH + H2
- more vigurously
- ignie H2
- lilac flame
Reactivity trend - Group 1
- increases
- number if shells increases
- easier to lose electrons
- nuclear charge increases = offset by shielding & large size
Rubidium/Caesium + Water
RbOH/CsOH + H2
* explosive
Reactivity trend - Group 7
- decreases
- shells increase & shileidng
- difficult to gain electron
- greater nuclear charge = offset by shielding
- harder to gain electrons
oxidation state
-ate = positive oxidation state
-ide= negative oxidation state
Disproportionation
same element is oxidised & reduced simultaneously in the same reaction
Acid rain
Corrosion caused by sulfur & nitrogen oxides dissolved in water
sulfur oxide origin
sulfur in fossil fuels & volcanic activity
nitrogen oxide origin
nitrogen in combustion of fuels & volcanic activity
acid rain effects
- ocean acidification
- reduces crop yield
- errodes building
- changes biology of lakes => kills fish
- reduce tree growth
dhhdhd
electronegativity
the ability of an atom to attract a bonding pair of electrons towards itself in a covalent bond
electron affinity
The energy required to add one mole of electrons to one mole of gaseous atoms
Is electron affinity endo or exo?
exo, bond making between e and nucleus!
How can electron affinity be affected ina. group
goign down group, electron affinity becomes less exo
* electrons are further from nucleus
* less attractive forces
* less energy given out when electrons are taken in
Reactivity of halogens
- reactivity decreases down group
- atomic radii increase
- electron affiity dcereases
- lower reactivity
