lecture 7 Flashcards

1
Q

what are the elements in group 2?

A

beryllium- Be magnesium- Mg calcium-Ca

strontium-Sr barium- Ba Radium-Ra

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2
Q

physical properties: atom size?

A

smaller than group A1

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3
Q

physical properties: atom size?

A

smaller than group A1

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4
Q

physical properties: melting point compared with group A1?

A

higher than group A1

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5
Q

physical properties: why are they a strong reagent?

A

because they readily lose valance electrons.

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6
Q

physical property that makes radium different.

A

all its isotopes are radio active

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7
Q

physical properties: divalent and ionic compounds:

A

are colorless.

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8
Q

physical properties: ionization energy compared to group A1

A

higher than group 1A

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9
Q

why is the ionization of A2 higher than A1?

A

because of the higher effective nuclear charge, and smaller size

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10
Q

physical properties: density compared to group A1

A

less dense than group A1

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11
Q

chemical properties: compared to group A1

A

less electropositive and less reactive but still reactive.

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12
Q

oxides of group 2A properties.

A

form basic solution.

melt at higher temperatures.

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13
Q

valance electron configuration.

A

ns^2

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14
Q

what is the element in group A2 that doesn’t behave like the rest of them.

A

beryllium

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15
Q

properties of beryllium.

A

steel gray, hard, high melting point, low density, high ressistance to corrosion, non-magnetic.

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16
Q

uses of beryllium

A

alloys to makes tough springs and non-sparking tools.
x-ray tube windows.
neutron source in nuclear reactor.
rockets and space craft

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17
Q

why is beryllium used in rockets and space crafts?

A

because of its light weight and strength

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18
Q

sources of beryllium?

A

bertrandite

beryl

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19
Q

bertrandite chemical formula

A

Be4S2O7(OH)2

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20
Q

beryl chemical formula and colors?

A

Be3Al2Si6O18

aquamarine
emerald

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21
Q

why causes the emerald color in beryl?

A

contaminated by Cr(III)

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22
Q

sources of magniesium?

A

common in sea water

mineral in nature

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23
Q

occurrence of magnesium

A

carnallite, dolomite epsomite, electrolysis of molten MgCl2

24
Q

carnallite chemical formula

A

KCl.MgCl2.6H2O

25
Q

dolomite chemical formula

A

MgCO3.CaCO3

26
Q

epsomite chemical formula

A

MgSO4.7H2O

27
Q

source of radium

A

radioactive decay of heavier elements.

28
Q

extraction of 2A group in general

A

electrolysis of molten chlorides with sodium chloride to lower the temprature.

29
Q

the chemical formula for electrolysis of molten chlorides

A

BeCl2-[electrolysis]-> Be(l) + Cl2

30
Q

the chemical formula for the extraction of Mg from seawater.

A

1- Mg^(+2) + CaO -> Mg(OH)2 + Ca^(+2)
2- Mg(OH)2 + 2HCl -> MgCl2 + H2O
3- MgCl2 (aq) -> MgCl2 (s) -> MgCl2 (l)
4- electrolysis

31
Q

extraction of Be from Beryl formula.

A

beryl + Na2SiF6 -[heat]-> BeF2 (aq) + Be(OH)2 (s)

  • reduction of BeF2
  • electrolysis of BeCl2
32
Q

extraction of Ca

A

electrolysis of CaCl2 and CaF2

33
Q

extraction of Strotrium and barium

A
  • reduction of corresponding oxides by Al

- electrolysis of MCl2

34
Q

uses of magnesium

A

aircraft, railroads, ships -> aluminum-magnesium alloy
lightweight alloys
reducing agent in the extraction of Si, Ti, Be
organic synthesis -> Gringard reagent
ingredient in fireworks and warning fire.
strong basic hydroxide.
essential to plant life.

35
Q

why is aluminum-magnesium alloy used in ships and aircraft?

A

due to its low density.

36
Q

why is Mg essential to plant life?

A

it is found in chlorophyll which keeps the molecules in a specific configuration.

37
Q

Ca occurrence

A

limestone calcite, marble, dolomite, gypsum (aka plasterboard), fluorite.

38
Q

marble chemical formula.

A

CaCO3

39
Q

dolomite chemical formula.

A

CaCO3.MgCO3

40
Q

gypsum chemical formula.

A

CaSO4.2H2O

41
Q

fluorite chemical formula.

A

CaF

42
Q

why is calcium carbonate important in biology?

A

dietary supplement, reduces osteoporosis, an antiacid consitutive.

43
Q

what is portland cement composed of?

A

dicalcium silicate, tricalcium silicate, tricalcium aluminate.

44
Q

extraction of Ca from CaCO3

A

CaCO3 + 2 HCl -> CaCl2 + H2O + CO2

electrolysis of CaCl2

45
Q

calcium uses.

A

in biology, portland cement, alloying agent. essential for living systems, forms slaked lime, neutralizing agent in gardening. bones.

46
Q

flame test results for Ca, Sr, Br

A

Ca-> orange-red
Sr-> crimson
Br -> apple green

46
Q

flame test results for Ca, Sr, Br

A

Ca-> orange-red
Sr-> crimson
Br -> apple green

47
Q

chemical reaction with oxygen

A

forms oxides.

48
Q

chemical reaction with water

A

forms dihydrogen gas.

49
Q

chemical reaction with halogens.

A

forms ionic halides.

50
Q

chemical reaction with dihydrogen

A

forms hydrides.

51
Q

chemical reaction with nitrogen

A

forms ionic nitrides

52
Q

chemical reaction with oxides

A

basic medium (except BeO)

53
Q

chemical reaction with carbonates

A

goes through thermal decomposition.

54
Q

limestone + heat

A

makes lime

55
Q

slaked lime reacts with carbon dioxide to make.

A

limestone.

56
Q

BaO2 + 2H2O -> …..

A

H2O2 + Ba(OH)2