AS.6 Periodicity Flashcards

1
Q

Periodicity

A

Repeating patterns and trends across a period of the periodic table

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2
Q

Trends in melting/boiling point across a period - giant metallic lattice structures

A

General increase

More delocalised electrons and higher ionic charge of cations
Higher electrostatic attraction
Stronger metallic bonds

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3
Q

Trends in melting/boiling point across a period - simple covalent lattice structures

A

E.g. period 3

P4 S8 Cl2 Ar
S8 P4 Cl2 Ar

All have London forces as strongest IMF
Decreasing number of electrons
S8 has more surface area contact points

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4
Q

Trends in melting and boiling point across period - giant covalent lattice structures

A

Covalent bonds are strongest

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5
Q

Comparing melting and boiling points across a period

A

Giant covalent

Giant metallic

Simple covalent

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6
Q

Group 2 reactions

A

Get oxidised
Lose 2 electrons

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7
Q

Group 2 reactivity down a group

A

Increases

Atomic radius increase

Shielding increase

Valence electrons further from nucleus

Nucleus attraction decrease

Donate more readily

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8
Q

MgCO3 and Mg(OH)2

A

Neutralising stomach acids

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9
Q

Ca(OH)2

A

Neutralising acidified soil

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10
Q

Metal and oxygen

A

Metal oxide

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11
Q

Metal and water

A

Metal hydroxide and hydrogen gas

Effervescence
Solid metal disappears

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12
Q

Metal and acid

A

Salt and hydrogen gas

Effervescence
Solid metal disappears

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13
Q

Metal oxide and water

A

Metal hydroxide

Solid metal disappears

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14
Q

Halogens reactions

A

Oxidising agent - electron acceptor

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15
Q

F2

A

Pale yellow gas

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16
Q

Cl2

A

Pale green gas

17
Q

Br2

A

Red/brown liquid

18
Q

Halogen oxidising ability trend

A

Decrease down group

Atomic radius increase

More shielding

Less nucleus attraction to outer electrons

Reactivity decrease

19
Q

Halogens in solution

A

Dissolve in water because polar

20
Q

Chlorine in water and cyclohexane

A

Water - pale green

Cyclohexane (more soluble) - pale green

21
Q

Bromine in water and cyclohexane

A

Water - orange

Cyclohexane- orange

22
Q

Iodine in water and cyclohexane

A

Water - dark brown

Cyclohexane- purple

23
Q

Halogens and halides

A

If halogen is strong enough oxidiser, it will accept electrons to form halide

The halide will donate electrons to form a halogen

X2 must be more reactive than X-

24
Q

Halogen colour

A

Depending on which halogen

25
Q

Halide colour

A

Colourless

26
Q

Disproportionation

A

When an element is both oxidised and reduced at the same time

27
Q

Chlorine and water

A

Cl2 + H2O ———————->HClO + HCl

Chlorine is reduced to HCl and oxidised to HClO

Used to treat water to kill bacteria (ClO-)

28
Q

Synthesis of bleach

A

Cl2 + 2NaOH ————> NaClO + NaCl + H2O

Chlorine is reduced to NaCl and oxidised to NaClO

29
Q

Test for CO3 2-

A

Add HNO3 (H+)
Effervescence

2H+ + CO3 2- ———-> CO2 (g) + H2O

30
Q

Test for SO4 2-

A

Add Ba(NO3)2 or BaCl2 (Ba 2+)
White precipitate

Ba 2+ + SO4 2- ——-> BaSO4 (s)

31
Q

Test for halides

A

Add AgNO3 (Ag+)
Precipitate

Ag+ + X- ——-> AgX (s)

32
Q

Test for chloride

A

White

Dilute ammonia - dissolves
Concentrated ammonia - dissolves

33
Q

Test for bromine

A

Cream

Dilute ammonia - no change
Concentrated ammonia - dissolves

34
Q

Test for iodide

A

Yellow

Dilute ammonia - no change
Concentrated ammonia- no change

35
Q

Order of tests

A

Carbonates
Sulfates
Halides

36
Q

Why the order of tests

A

False positives

When testing for sulfates - rule out carbonate as carbonates will produce precipitate of BaCO3

When testing for halides - rule out sulfate as sulfate would produce precipitate of Ag2SO3

37
Q

Test for ammonium cation

A

NH4+

Heat gently with NaOH in boiling tube
Place moist red litmus paper near tube opening
If positive - blue

NH4+ + OH- ———> H2O + NH3