group 2 Flashcards

1
Q

what is the trend in atomic radius

explain

A

increases

more electrons so no. energy levels increases, new completed energy level each increment, atoms get bigger.

[ rate of increase decreased due to stronger nuclear charge ]

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2
Q

trend in 1st ionisation energy

A

decreases

increased atomic distance due to increased no energy levels so further distance between outer electron being removed and nucleus. FoA is weakened

more shielding due to more completed energy levels which decreased FoA between .. .

less energy is needed to overcome FoA

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3
Q

trend in melting points

A

overall decreases because larger ionic radius of metal ions in giant metallic lattice leads to further distance between +ve nucleus and delocalised system.
more shielding between delocalised system and nucleus
same charge / delocalised e- per atom

so less FoA to overcome

Mg is less than everyone

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4
Q

trend in electronegativity

A

atomic radius and shielding increases

so bonding is less strong

bonding e- are less strongly attracted to the nucleus

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5
Q

reaction of Mg with cold water

A

(slow)

Mg + H2O – Mg(OH)2 + H2

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6
Q

reaction on Mg with steam

A

Mg + H2O – MgO + H2

MgO burns with a white flame

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7
Q

Calcium and water

A

Ca + 2H2O – calcium hydroxide+ hydrogen

reaction mixture is cloudy bc hydroxide not v soluble

Ca has a protective layer of CaO so there’s a lag

effervescence

alkaline

Ca sinks bc more dense than water

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8
Q

general equation for G2 metals and water

A

G2 metals and water – metal hydroxide and hydrogen

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9
Q

trend in reactivity

explain

A

increase; Mg needs a lot of energy whereas Ba happens quickly

outer e- are further from nucleus bc increasing atomic radius;
atoms are bigger;
more e- levels so increased shielding;
e- are lost more easily because eFoA between .. is weaker

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10
Q

equations of Mg in the extraction of titanium

A

titanium ore = TiO2

TiO2 + C + Cl2 – TiCl4 + CO2

TiCl4 + 2Mg – Ti + 2MgCl2

Mg is used to displace Ti from the chloride compound

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11
Q

trend in solubikity of G2 hydroxides, M(OH)2

A

increases as go down the group

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12
Q

magnesium hydroxide solubility

use

A

insoluble almost

used as milk of magnesia, an antacid which neutralised excess stomach acid to help with indigestion

milk of magnesia is a suspension not a solution

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13
Q

calcium hydroxide solubility and use

A

sparingly soluble; j ab dissolves

slaked lime
- used to neutralise acidic soil
- used by farmers

lime water
- detected carbon dioxide gas by bubbling gas through it, if goes cloudy
- Ca(OH)2 + CO2 – CaCO3 + H20
- calcium carbonate is insoluble therefore white precipitate

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14
Q

Strontium hydroxide solubility

A

soluble

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15
Q

barium hydroxide solubility and use

A

readily soluble in aq solution, produces strong alkali;
to soluble is to dissociate

used to test for sulfate ions

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16
Q

how is barium hydroxide used as a sulfate test

A
  1. acidify sample w HCl or HNO3 to remove any ionsthat would interfere with test. they would react with Ba2+ ions and give false result
  2. add solution containing Ba2+ ions eg BaCl2
  3. if sulfate ions are present you get a white precipitate of BasO4 (insoluble)
17
Q

trend in solubility of G2 metal sulfates

MSO4

A

decreases

18
Q

MgSO4 solubility and use

A

v soluble
antacid for indigestion

name: andrew salt (solution)

19
Q

BaSO4 solubility and use

A

virtually insoluble, therefore useful in medicine as a barium meal

liquid passes through digestive tract and sits in intestine

BA2+ ions are good at absorbing x-rays, similar to minerals in bone

if you have breaks or leaks in the truck that will show or blockage will be shown by the absence of ba2+

ba2+ ions are toxic but because it is insoluble the ions won’t be absorbed

20
Q

can investigate solubility of G2 hydroxides how

A

mixing soluble G2 salts with NaOH

will form G2 hydroxides

will see trend in solubility

21
Q

can investigate solubility of G2 sulfates how

A

mixing solutions of G2 sulfates with sulfuric acid

SO42- will add on to metal ions

trend seen