3.1 periodic table Flashcards
where is the s-block?
groups 1 and 2
where is the p-block?
groups 3, 4, 5, 6, 7 and 8
where is the d-block?
transition metals
where is the f block
lanthanides and actinides (at the bottom)
define periodicity
trends in properties that are repeated and occur across the periods of the periodic table
define 1st ionisation energy
the energy required to remove 1 mole of gaseous electrons from 1 mole of a gaseous atom
state and explain the trends of ionisation energy across the periodic table
increases from left to right –>
- no extra shielding
- more protons
- smaller atomic radii
- greater nuclear attraction
- more energy required to remove electron
state 3 factors affecting 1st ionisation energy
atomic radius
electron shielding
nuclear charger
state and explain the trends in melting point across periods
- increases from group 1 to group 3:
• nuclear charge increases
• electrons feel greater nuclear attraction - peaks at group 4
• giant covalent structures require lots of energy to break their covalent bonds - decreases until group 8
• weak intermolecular forces - little energy to be broken
• peak in period 3 in sulphur because it has a larger electron cloud - S₈
state the trends in atomic radius
increases from top to bottom
increases from right to left
name 2 exceptions to the trends in ionisation energy
- between groups 2 and 3: group 3 elements have outer electron in p orbital, which is further from the nucleus and therefore easier to be removed. group 2 elements have outer electron in s orbital. group 2 > group 3
- between groups 5 and 6: outer electrons in group 6 elements experience “spin pair repulsion” as they are paired in an orbital. this repulsion makes them easier to remove. group 5 elements’ outer electrons are not paired group 5 > group 6
state the trend in nuclear charge in the periodic table
nuclear charge increases from left to right
define electron shielding
the repulsion of electrons in different inner shells. shielding reduces the attractive force between the nucleus and outer electrons.
state the trend in electron shielding in the periodic table
electron shielding increases down the group
define effective nuclear charge
the net positive charge experienced by an electron in an atom with more than one electron.
define malleable
something that can be hammered into shapes
define ductile
something that can be drawn into wires and rods
bigger positive ion = ______ bond strength. why?
bigger positive ion = WEAKER bond strength
eg. group 2 metals - each one makes a 2+ ion and have 2 mobile electrons per ion - for bigger ions, electrons are more spread out, making them less effective at attracting the big ions together - weaker bond strength/weaker electrostatic force
define successive ionisation energy
the sequence of first, second, third etc. ionisation energies needed to remove the first, second, third etc. electrons from each atom in one mole of gaseous atoms of an element
what is the trend of successive ionisations energy? why?
SIE increases each time 1st < 2nd < 3rd < 4th etc
because electrons are being removed from a more positive species/nucleus so this requires more energy.
name the group 2 elements in order
beryllium Be, magnesium Mg, calcium Ca, strontium St and barium Ba
state and explain the trend of melting point in group 2
MP DECREASES DOWN GROUP 2 because size of the ion increases = the bonding electrons become further from the positive nucleus = reduces attraction = lower melting point.
state and explain the trend of atomic and ionic radius in group 2
ATOMIC & IONIC RADIUS INCREASE DOWN GROUP 2 because more electrons = more shells = outer electron becomes further from nucleus
state the trend of electron configuration in group 2
each element gains another shell and moves to the next s-orbital. e.g. Be: …2s2 - Mg: …3s2 Ca: …4s2 etc.
state and explain the trend of 1st ionisation energy in group 2
IE DECREASES DOWN GROUP because atomic radius and electron shielding increases - electrons feel less attraction to the nucleus - easier to lose - less energy is required to remove them
describe and explain the SIE graph of a typical group 2 element
1st and 2nd IEs are close together and then the 3rd IE takes a large jump up - the 3rd electron is closer to the nucleus in a different shell - much more energy to be removed
give the equation of the 2nd IE of Mg
M⁺(g) → M²⁺(g) + e⁻
MUST HAVE STATE SYMBOL
state and explain the trend of reactivity in group 2
REACTIVITY INCREAEES DOWN GROUP 2 because the 2 outer electrons become easier to lose as they get further from the nucleus - effective nuclear charge = less, so reactivity increases.
group 2 reaction with WATER: which element doesn’t react?
whats the general symbol equation?
what does it form?
Be doesn’t react with water.
general formula: X + 2H₂O → X(OH)₂ + H₂
a hydroxide and hydrogen gas are formed e.g. Mg(OH)₂
group 2 reaction with OXYGEN:
how do they react?
general formula?
what is made?
react vigorously
gf: 2X + O₂ → 2XO
produces metal oxide
group 2 reactions with ACIDS (Hal):
how do they react?
general formula?
what does it produce?
vigorously
gf: X + 2HCl → XCl₂ + H₂
produces a salt and hydrogen gas
group 2 solubility of METAL HYDROXIDES and OXIDES:
- which hydroxide is not soluble?
- what is the trend of solubility?
- name and describe the trend in pH of the aqueous hydroxides
- Be(OH)₂ is NOT soluble
- solubility INCREASES DOWN the group
- pH/alkalinity INCREASES DOWN because they become more soluble = release more OH- ions = more alkaline = higher pH
group 2 solubility of METAL SULPHATES:
what is the solubility trend?
solubility decreases down the group
what is made from reacting a metal oxide and water?
metal hydroxide
which group 2 hydroxide is used to reduce acidity of soil?
why?
whats the gf?
Ca(OH)₂ is used because its a base so will neutralise the acids in the soil.
gf: Ca(OH)₂ + 2HCl → CaCl₂ + 2H₂O
forms salt and water
what causes indigestion?
too much build of Hal in the stomach
which metal hydroxide and metal carbonate are used for indigestion tablets?
Mg(OH)₂ and CaCO3
eg. milk of magnesia
in which block are the group 7 elements?
p-block
what do all the group 7 electron configurations end in?
_s2_p5
e.g. Cl —> 2s2 2p5
Br —> 3s2 3p5. etc
state and explain the trend in boiling (and melting) point in group 7
BOILING POINT INCREASES DOWN GROUP 7
because each element gains an extra shell/has more electron - more electrons = stronger dipole and stronger induced dipole dipole interactions - more energy required
state and explain the trend in ionic and atomic radius in group 7
IONIC AND ATOMIC RADII INCREASE DOWN GROUP 7
because increasing electron number = more shells = larger atom = larger radius
state and explain the trend of 1st ionisation energy in group 7
1st IE DECREASES DOWN GROUP 7
- because outer electrons get further from nucleus
- outer electrons feel less attraction to nucleus
- easier to lose
- less energy required = lower IE
describe the graph of SIE of a typical group 7 element
there’s a jump between the 7th and 8th IE because the 8th electron requires more energy to be removed because there’s less shielding because a whole shell has been lost in the first 7 IEs
state and describe the trend of reactivity in group 7
REACTIVITY DECREASES DOWN GROUP 7 (fluorine is most reactive)
- because atomic radius increases down group so electron joining the outer shell feel less attraction
- electron shielding increases because more shells are added down the group
- ability to gain an electron decreases
group 7 displacement / redox reactions:
between which two substances do they occur?
aqueous halide ions (Cl-, Br- and I- etc) and aqueous halogens (Cl2, Br2 and I2 etc)
group 7 displacement / redox reactions:
how do they reactions occur? what happens?
if the halogen is more reactive then the halide, the halogen OXIDISES the halide (takes away electrons from) the halide
halide becomes a halogen
halogen becomes halide
what must the halogens and halides be for a displacement reaction to take place?
aqueous
what colour do the following make in WATER:
chlorine
bromine
iodine
cl: pale green
br: orange
i: brown
what colour do the following make in CYCLOHEXANE:
chlorine
bromine
iodine
cl: pale green
br: orange
i: violent
define disproportionation
the oxidation and reduction of the same element in one reaction
(the same element gets oxidised and reduced in one reaction)
what two processes can chlorine be used for?
water purification
making household bleach
why is chlorine good for water purification?
cl kills bacteria in the water, making it safe to drink
what is the symbol equation for water purification? what are the products?
Cl2 + H2O —> HClO + HCl
products are - chloric (I) acid and hydrochloride acid
bleach forming an water purification are __________ reactions because ….
disproportionate because chlorine is reduced and oxidised in both reactions
what does chlorine react with in bleaching forming?
dilute aqueous sodium hydroxide NaOH (aq)
what is the symbol equation for bleach forming? what are the products?
Cl2 + 2NaOH —> NaCl + NaClO + H2O
products: sodium chloride, sodium hypochlorite and water
why is chlorine good for making bleach?
it has bleaching action
it is only slightly soluble in water
how do you test for carbonate ions?
how do you know the carbonate ions are present?
react the substance with an acid.
if carbonate ions present:
- fizzy/colourless has produced
- the gas turns turns lime water cloudy
how do you test for sulphate ions?
how do you know sulphate ions are present?
add HCl and barium chloride to the substance - sulphate ions react with barium to form insoluble barium sulphate.
if so4 ions present:
- white precipitate forms which is the insoluble BaSO4
how do you test for halide ions?
4 steps
halide ions react with silver ions to form precipitates - AgX
- dissolve halide substance in water
- add aqueous silver nitrate
- look at the colour
- if no colour is identified, add aqueous ammonia for clearance and clarification
how do you know if chloride ions are present in a halide test?
chloride ions:
- white precipitate forms
- soluble in DILUTE aqueous ammonia
how do you know if bromide ions are present in a halide test?
bromide ions:
- cream precipitate forms
- soluble in CONCENTRATED aqueous ammonia
how do you know if iodide ions are present in a halide test?
iodide ions:
- yellow precipitate forms
- NOT SOLUBLE in any ammonia
how do you test for ammonium ions? (2 steps)
ammonium ions react with hydroxide ions to form ammonia and water
- add sodium hydroxide to the substance
- warm it gently
when testing for ammonium ions, how do you know if it is present in the solution?
- gas turns litmus paper red
- ammonia gas has a distinct smell (hazardous smell)
state and explain the trend in ionisation energy in groups in the periodic table
ionisation energy decreases down groups
- more shells
- outer electrons further from nucleus
- more shielding
- less nuclear attraction
- less energy needed to remove electrons
