Period 3 Flashcards
(46 cards)
What elements are the in s-block?
elements with their outer most electron in an s orbital
What elements are in the d-block?
elements with their outer most electron in an d orbital
What elements are in the p-block?
elements with their outer most electron in an p orbital
What is the general trend down a group?
- Increase in atomic number- Increase in shielding- Increase in atomic radius- Decrease in effective nuclear charge- Decrease in 1st ionisation energy- Decrease in electronegativity
What is the general trend across a period?
- Increase in atomic number- Shielding remains the same- Decrease in atomic radius- Increase in effective nuclear charge- Increase in 1st ionisation energy- Increase in electronegativity
What happens to atomic radius as you go across period 3 and why?
Atomic radius decreases because - increase in nuclear charge- same shielding- electrons drawn closer to the nucleus, decreasing radius
What happens to first ionisation energy as you go across period 3 and why?
First ionisation energy increases - increase in nuclear charge- same shielding - greater attraction of outer electrons to nucleus therefore more energy needed to remove an outer electron (Mg to Al and P to S are exceptions because of orbitals)
What happens to melting and boiling point as you go across period 3 and why?
- Slow increase from Na to Al because of there metallic bonding. It increases with increased charge on the positive ions because there are stronger electrostatic attractions - Giant spike to Si because it is a giant covalent structure, very high because strong covalent bonds need to be broken- Small decrease to P4, small increase to S8 and gradual decrease to Ar because induced dipole forces only and the trend will vary based on size of the molecule because size of ID forces is directly linked to Mr (no. of electrons involved in I.D.)
What’s the trend in atomic radius across period 3 and why?
Decrease in atomic radius because shielding is unchanged and there is an increase in nuclear charge
What is the trend in 1st ionisation energy across period 3 and why?
It is a general increase but there is a dip at Al due to 3s orbital shielding and a dip at S due to 3p electron pair sheilding
What is the bonding across Period 3?
- Na -> Al metallic- Si -> Giant covalent- P -> Cl Molecular/ Simple covalent- Ar -> Monatomic
What is the trend in melting points across Period 3?
- Increase from Na to Al because ionic charge increases so there is greater electrostatic attractions with electrons - Spike at Si because of the strong covalent bonds- Increase from P to S because of the increase in Mr so the increased strength of Vanderwaals forces- Decrease from S to Ar because of the decrease in Mr so the decreased stength of the Vanderwaals forces
Which period 3 elements react with water?
Na, Mg and Cl
What is observed when Na reacts with water?
- Exothermic- Strong alkali (2NaOH)- Fizzing as H is produced
What is observed when Mg reacts with water?
- Very slow- A white precipitate of Mg(OH)2 is formed - Hydrogen is produced slowly therefore no fizzing
How can the reaction of Mg with water be sped up?
React it with steam
What is observed when Mg is reacted with steam?
- Faster rate of reaction - Solid oxide of MgO formed
What can be observed when Cl reacts with water?
- Disproportionation reaction therefore Cl is both oxidised and reduced- HClO and HCl produced
What is observed when Na reacts with oxygen?
- Yellow flame- White solid 2Na2O- Ionic and basic
What is observed when Mg reacts with oxygen?
- White flame- White smoke- Ionic and basic- 2MgO solid produced
What is observed when Al reacts with oxygen?
- White flame- White solid- Ionic and amphoteric- 2Al2O3 solid produced
What is observed when Si reacts with oxygen?
- White flame- Whiteish solid SiO2 produced- Giant covalent and acidic
What is observed when P reacts with oxygen?
- White flame- White solid P4O10 - Simple covalent and acidic
What is observed when S reacts with oxygen?
- Blue flame- pungent gas- Simple covalent and acidic- SO2 gas produced which can rereact with oxygen with a V2O5 catalyst to produce 2SO3 gas
What are the 7 period 3 oxides?
- Na2O
- MgO
- Al2O3
- SiO2
-P4O10
-SO3
-SO2
Out of MgO and Na2O which oxide has the greatest melting point and why?
MgO>Na2O
due to the greater charge on the metal ion therefore stronger electrostatic attraction to the O2-
Out of MgO and Al2O3 which oxide has the biggest melting point and why?
Al2O3 < MgO because Al2O3 shows some covalent character
What is notable about SiO2 's melting point?
Melting point is lower than the three ionic but higher than the three molecular covalent due to it being giant covalent so strong covalent bonds must be broken to melt
What is the melting point trend from P4O10 to SO2 ?
Decrease due to them being molecular covalent and melting point being linked to Mr. Higher Mr = stronger Van der Waals tehrefore higher melting point
How is Na2O neutralised?
It is basic so is neutralised by an acid. E.g. adding 2HCl to form H2O and 2NaCl
How is MgO neutralised?
It is basic so is neutralised by an acid. E.g. adding 2HCl to form H2O and MgCl2
How can Al2O3 be neutralised?
It is amphoteric so can be neutralised by either an acid or a base.
E.g. adding 6HCl to form 2AlCl3 and 3H2O
E.g. adding 2NaOH and 3H2O to form 2Na+ + [Al(OH)4]- (Aluminate)
How is SiO2 neutralised?
It is acidic so is neutralised by a base. E.g. + 2NaOH to form H2O and Na2SiO3 (silicate)
How is P4O10 neutralised?
It is acidic so is neutralised by a base. E.g. + 12NaOH to form 6H2O and 4Na3PO4 (Phosphate)
How is SO2 neutralised?
It is acidic so is neutralised by a base. E.g. + 2NaOH to form H2O and Na2SO3 (sulfite)
How is SO3 neutralised?
It is acidic so is neutralised by a base. E.g. + 2NaOH to form H2O and Na2SO4 (sulfate)
