What is the trend in atomic radius across period 2/3? Why?
decreases > increased nuclear charge > more positive charge of attraction > with electrons on the same shell
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What are the elements in period 3?
Na, Mg, Al, Si, P, S, Cl, Ar
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What are the blocks?
s-, p-, d-, f-
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What does the term periodicity mean?
trends in the properties of the elements
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How is the periodic table organised?
groups (columns), periods (rows), non-metals and metals,
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Who is Dmitri Mendeleev?
the father of the periodic table. Left gaps for undiscovered elements > arranged elements with similar properties. There are new elements that fit the gap.
metals/ non-metals > forms ionic/ covalent > molecules
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What are group 7?
non-metals > covalent bonding > molecules
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What are the b.p.t/m.p.t trends of period 3?
the general trend of increasing then decreases - from metals to non metals
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Why does Silicon have the highest b.p.t/m.p.t in period 3?
because of it's a macromolecule, requires a lot of energy to break the strong covalent bonds
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What are the b.p.t/m.p.t trends of Na, Mg & Al?
b.p.t increases, because nuclear charge increases, so more delocalised 'sea' of electrons, therefore holds the giant metallic lattice together
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What are the b.p.t/m.p.t trends of P4, S8, Cl2?
decreases, apart from S8 increases, as it all depends on the v.d.waals forces, S8 has more electrons therefore a stronger v.d.waals forces, requiring more energy to separate the molecules
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Why does Ar have the lowest b.p.t/m.p.t?
because it is a noble gas and is very unreactive, and very weak v.d.waals forces
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What are the b.p.t/m.p.t trends of period 2?
similar trend to period 3, metals (increases), macromolecule (v.high), molecules (low), monoatomic (v.low)
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What is the atomic radii trend for period 2 & 3?
decreases across a period because there is an increased nuclear charge > creates a more positive charge of attraction > for electrons which are on the same shell/ similar shielding > therefore electrons are pulled closer together
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Define: 1st ionisation energy.
the energy required to remove an electron from 1 mole of gaseous atoms to form a +1 ion
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What is the general trend of the 1st i.e across period 3?
increases due to the increasing number of protons as the electrons are being added to the same shell of the same shielding
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Why is there a drop between Mg and Al?
Al has a lower i.e than Mg because Mg has it's outer electron in the 3s sub shell; whereas Al is starting to fill up 3p sub shell > Al's electron is easier to remove because 3p electrons are higher in energy
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Why is there a drop between P and S?
S has a lower i.e than P because S's outer electron is being paired up with an another electron of the same 3p orbital > when a second electron is added there is a repulsion between the negative electrons > making it easier to remove the second e-
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What is the general trend of the 1st i.e across period 2?
the same trend as period 3 with drops between Be &B and N&O for the same reasons (2s and 2p instead of 3s and 3p)
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Define: 2nd ionisation energy.
the energy required to remove a second electron from a positive ion from 1 mole of gaseous atoms
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Other cards in this set
Card 2
Front
What is the trend in atomic radius across period 2/3? Why?
Back
decreases > increased nuclear charge > more positive charge of attraction > with electrons on the same shell
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