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A level Chemistry > Period 3 > Flashcards

Period 3 Flashcards

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1
Q

Across period 3, shielding…

A

stays the same

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2
Q

across period 3 the nuclear charge

A

increases as we go across

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3
Q

therefore across period 3 the nuclear attracts the electrons

A

more

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4
Q

across period 3 the atomic radius

A

decreases

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5
Q

the first ionisation energy across period 3 generally

A

increases
moving across a period number of electron shields remain the same so shielding remains the same
however nuclear charge increases therefore attraction between nucleus and outermost electron increases

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6
Q

Explain why the first ionisation energy of aluminium is less than magnesium

A

The outermost electron of aluminium is in a P orbital whilst magnesium is in an S orbital

electrons in the S orbital repel and shield the electrons in the P orbital to some extent

this means less energy is required to remove the first electron in the P orbital of aluminium

therefore aluminium has a lower first ionisation energy

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7
Q

explain why the first ionisation energy of sulphur is less than phosphorus

A

phosphorus has only 1 electron of its p orbital

sulphur has 2 electron in one of its p orbitals causing increases electron repulsion

meaning less energy is required to remove an electron from sulphur

therefore sulphur has lower first ionisation energy than phosphorus

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8
Q

Which of these form metallic bonding

Sodium
Magnesium
Aluminium
Silicon
Phosphorus 
Sulphur 
Chlorine
Argon
A

Sodium , Magnesium and aluminium are all metals

therefore are held together by metallic bonding

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9
Q

In period 3, the elements from phosphorus to chlorine all form…
What is argon?
What is silicon

A

covalent bonds.

Argon is inert and doesn’t really form bonds
Silicon is neither a metal or non metal so it’s a metalloïd and forms many strong covalent bond the result is a giant covalent lattice

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10
Q

What is the trend between the first period 3 elements of Na, Mg and Al
explain the reason why?

A

Na < Mg < Al
Na is lower melting point than magnesium
Magnesium has a lower melting point than aluminium

moving from sodium to aluminium the charge on the metal cation increases an snubber of delocalised electrons per cation increases

therefore attraction between the metal cation and delocalised electrons increased and strength of metallic bonding increases

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11
Q

Between Silicicon, Phosphorus, Sulphur, Chlorine and argon rank the melting points from 1(highest) to 5 (lowest

A 
Silicon 1
phosphorus 3
sulphur 2
chlorine 4
argon 5
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12
Q

How many atoms are in a molecule of

Phosphorus 
Sulphur
Chlorine 
Argon
l
A 
Phosphorus = 4
Sulphur = 8
Chlorine = 2
Argos = 1
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13
Q

Explain why phosphorus has a lower melting point than sulphur

A

Phosphorus exists as P4 molecules whilst Sulphur exists as S8

therefore sulphur is bigger than phosphorus and sulfur has more electron than phosphorous

meaning van der waals forces are stronger so more energy is required to break the intermolecular force of sulphur compared to phosphorus

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14
Q

Predict the general trend in atomic radius across period 5 and why

A

atomic radius decreases

because nuclear charge increases and there is more attraction between the outermost electrons and the nucleus

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15
Q

predict the general trend in the first ionisation energy across period 5 and why

A

first ionisation energy increases because nuclear charge increases an ethereal is more attraction between the outermost electrons and the nucleus

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16
Q

Between which period 2 element does the first ionisation energy decrease?

A

beryllium and boron decrease between group 2 and 3
and nitrogen and oxygen decrease between group 5 and 6

period 2 has the same trend in the first ionisation energy as period 3

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17
Q

Complete the balanced equation

2Na (s) + 2H2O —>

A

2Na (s) + 2H2O —> 2NaOH (aq) + H2 (g)

18
Q

State the full balanced equation for the reaction between magnesium and steam

A

Mg (s) + H2O (g) —> MgO (s) + H2 (g)

19
Q

the reaction of cold water with sodium is

A

faster than the reaction of cold water with magnesium

20
Q

Magnesium hydroxide forms a much less alkaline solution because it has a much lower

A

solubility than sodium hydroxide

21
Q 
Give the formula of the highest oxide of 
Sodium 
magnesium 
aluminium
silicon 
phosphorus
sulphur
A 
sodium = Na2O
magnesium= MgO
Aluminium = Al2O3
Silicon = SiO2
Phosphorus = P2O5
sulphur = SO3
22
Q

What is observed when the sodium magnesium red phosphorus white phosphorus sulphur are heated with oxygen?

A

Sodium = white powder and yellow flame flame forms

magnesium = white powder and white flame forms

red phosphorus= white powder and white smoke forms

White phosphorus = white powder and white smoke forms

sulphur = blue flame forms

23
Q

What are the oxidation states of sulphur in the following molecules
H2S
SO2

A 
H2S = -2
SO2 = +4
24
Q

Give the chemical formula for sulfur (IV) oxide

A

SO2

25
Q 
Which of the following oxides form ionic lattices?
Na2O
MgO
NO
K2O
SiO2
A

Na2O, MgO and K2O

26
Q

What holds a SO2 molecule together ?

A

covalent bonds because sulphur and oxygen are both non metals
non metals are held together in molecules by covalent bonds

27
Q

What force exists between molecules of SO2

A

van der waals and dipole dipole forces

all covalent molecules experience intermolecular forces
all covalent molecules experience van der waals forces
SO2 has a dipole n will experience dipole dipole forces

28
Q

How many oxygen atoms are there in the highest oxide of Phosphorus and sulfur?

A 
phosphorus = 5, 10
sulfur = 3
29
Q

Giant lattices can be macromolecules or ionic lattices

what do we know

A

ionic lattices consist of oppositely charged ions

and both types of structures have very high melting points relative to molecular lattice

30
Q

Explain the following melting point trend

P4O10 > SO3 > SO2

A

all 3 form molecular lattices & held together by intermolecular forces meaning we must consider van der waals which depend on size of molecule

the size of molecules follow the trend P4O10 > SO3 > SO2

therefore melting point also follows the same trend as the arrow

31
Q

explain how covalent cb drafter of aluminium oxide arises

A

aluminium cation is very small
meaning aluminium cation is closer to the oxide ion
the cation is also very highly charged enough to distort the electron cloud
therefore electron cloud appears more covalent

32
Q

What oxide reacts with water to form an acidic solution?

A

P4O10 , SO2 and SO3

33
Q 
Predict the pH of 1 mol dm -3 of the final something when the following reacts with water 
MgO
SO3
P4O10
Na2O
A

MgO = 9/10
SO3= 0/1
P4O10= 1/2
Na2O =13/14

34
Q

Why doesn’t SiO2 react with water?

A

water can’t break apart the giant covalent lattice of SiO2

35
Q

State the equation for the reaction. between sulfuric trioxide and water
and sulfur dioxide and water

A

SO3 (l) + H2O (l) —> H2SO4 (aq)

SO2 (g) + H2O (l) —> H2SO3 (aq)

36
Q

moving across period 3 the ph in aqueous solution if the highest oxides …

A

decreases

37
Q

silicicon dioxide reacts with

A

strong bases

38
Q

write the balanced equation for the reaction between silicon dioxide and hot concentrated sodium hydroxide

A

SiO2 (s) + 2NaOH (aq) —> Na2SiO3 (aq) + H2O (l)

39
Q

Phosphorus (V) oxide reacts with

A

water and bases

40
Q

write the balanced equation reaction for the over reaction between phosphorus oxide and potassium hydroxide

A

P4O10 (s) + 12KOH —> 4K3PO4 (aq) + 6H2O (l)

41
Q

what oxide forms a base without forming an acid when added to aqueous alkaline solution ?

A

SiO2 and SO2

as P4O10 and SO3 react vigorously with water so that effectively tbh eur reaction with an alkaline aqueous solution happens in 2 stages
first they react with water to form an acid
then secondly the acid reacts with the base
reaction of these 2 stages is the same as the direct reaction which would occur in absence of water

42
Q

SO2 (aq) + 2NaOH (aq) -> .. (aq) + H2O (l)
SO3 (l) + 2NaOH (s) —> … (aq) + H2O (l)

state the missing product in these equations

A

1) Na2SO3

2) Na2SO4

A level Chemistry (12 decks)

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