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Chemistry - AS > 6. Periodic Table > Flashcards

6. Periodic Table Flashcards

1
Q

s block elements

A

s-block elements, those found in Group 1 and 2, are metals that form basic oxides. They are reducing agents, so they donate electrons and form cations easily. Their melting point decreases down the group.

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2
Q

p block elements

A

p-block elements are non-metals that form acidic oxides. They are oxidising agents. Those in Group 6 and 7 can accept electrons and form anions easily. Their melting point increases down the group.

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3
Q

d block elements

A

d-block elements are transition metals.

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4
Q

Oxidation Rules

A

All combined elements have an oxidation number of zero: O2 = 0

REMEMBER THAT FIRST ONE!!!!!

Gp 1 metals have an oxidation num of + 1, Gp 2 have +2

Gp 6 usually have -2, Gp 7 usually have -1
The oxidation number of oxygen is -2 except in peroxides (in H2O2 it is -1)

The oxidation num of hydrogen is +1 except in metal hydries e.g NaH where hydrogen is -1.

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5
Q

s block elements + oxygen

A

Group 1:

4X + O2 -> 2X2O

X = Li,Na,K

Group 2:

2X + O2 -> 2XO

X = Mg,Ca,Sr,Ba

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6
Q

s block elements + water

A

Group 1 :

2X + 2H2O -> 2XOH + H2

Group 2:

Magnesium:
Mg + H2O -> MgO + H2

Others:

X + 2H2O -> M(OH)2 + H2

X = Ca,Sr,Ba

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7
Q

OH-, CO32- and SO42- Reactions with Gp 2 Metals

A

OH- CO32- SO42
Mg2+ insoluble insoluble soluble
Ca2+ !soluble insoluble “soluble
Sr2+ “soluble insoluble !soluble
Ba2+ soluble insoluble insoluble

! = sparingly
“ = moderately

(All precipitates are white)

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8
Q

Halogen + Sodium
Halogen + Iron

A

Flame - Bright Orange
Colour - White Solid Halide

Iron wool will glow and then burn in halogen vapour to form iron halides which appear as a brown gas

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9
Q

Test For Halide Ions

A

Chloride
- Silver Nitrate - White ppt
- Ammonia - dissolves in dilute NH3

Bromide
- Silver Nitrate - Cream ppt
- Ammonia - dissolves in concentrated NH3

Iodide
- Silver Nitrate - Pale yellow ppt
- Ammonia - does not dissolve in NH3

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10
Q

Displacement Table

A

Chloride ->
NaCl - X
NaBr - Colourless to pale yellow
NaI - Colourless to pale brown

Bromide ->
NaCl - No colour change
NaBr - X
NaI - Pale yellow to pale brown

Iodide
NaCl - No colour change
NaBr - No colour change
NaI - X

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11
Q

Why are the halogens oxidising agents?

A

gaining one electron completes shell

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12
Q

What is the strongest oxidising agent?

A

Fluorine as it has the least shielding and greatest effective nuclear charge. Oxidising power decreases as group is descended.

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13
Q

How to identify halides and gp 2 metals

A

Halides - silver nitrate

gp 2 metals

To identify magnesium compounds -
add sulfuric acid
magnesium compounds gives solution, calcium and barium compounds gives ppt

To identify barium compounds -
add sodium hydroxide
- barium compounds gives solution, calcium and magnesium compounds gives ppt

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14
Q

Standard Solution

A

1.Weigh precise mass of solid
(primary standard - large Mr,stable, doesnt absorb water)

  1. Transfer into beaker and reweigh

3.Dissolve in beaker in small vol of deionised H2O

  1. Transfer into xcm3 volumetric flask + rinse through thoroughly
  2. Make up to mark with deionised H2O
  3. Invert to homogenise
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15
Q

Titration

A
  1. Add xcm3 of ? to xcm3 concial flask using xcm3 pipette
  2. Add a couple drops of indicator
  3. Using burette slowly add ? with swirling
  4. Record volume when indicator changes colour
  5. Repeat + record mean (concurrent +-0.2cm3)

Indicators:

Phenophalein (pink to colourless)
Methyl orange (orange to pink)

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16
Q

Recrystalisation

A
  1. Dissolve in minimum hot solvent (least volume to get most back)

(If needed) 2. filter hot to remove impurities

  1. Cool and cystalise
  2. Filter + wash with a couple of drops of ice cold solvent to remove surface impurities
  3. Dry to constant mass - no solvent left
17
Q

Gravimetric

A
  1. To a known quantity of ? (e.gCl-) and excess preciptatating agent (e.gAgNO3) (to create solid ppt - excess so all is reacted)
  2. Filter - to seperate ppt - weigh filter paper
  3. Add AgNO3 ? to filtrate - if cloudy filter + repeat
  4. Wash witha couple drops of cold solvent
  5. Dry to constant mass
18
Q

Redox Rxn and Water Treatement

A

NaCl + H2SO4 -> NaHSO4 + HCl

Cl2 + H2O -> OCl- + Cl- + 2H+

Chemistry - AS (15 decks)

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