lecture 7

Question 1

what are the elements in group 2?

Answer 1

beryllium- Be magnesium- Mg calcium-Ca

strontium-Sr barium- Ba Radium-Ra

Question 2

physical properties: atom size?

Answer 2

smaller than group A1

Question 3

physical properties: atom size?

Answer 3

smaller than group A1

Question 4

physical properties: melting point compared with group A1?

Answer 4

higher than group A1

Question 5

physical properties: why are they a strong reagent?

Answer 5

because they readily lose valance electrons.

Question 6

physical property that makes radium different.

Answer 6

all its isotopes are radio active

Question 7

physical properties: divalent and ionic compounds:

Answer 7

are colorless.

Question 8

physical properties: ionization energy compared to group A1

Answer 8

higher than group 1A

Question 9

why is the ionization of A2 higher than A1?

Answer 9

because of the higher effective nuclear charge, and smaller size

Question 10

physical properties: density compared to group A1

Answer 10

less dense than group A1

Question 11

chemical properties: compared to group A1

Answer 11

less electropositive and less reactive but still reactive.

Question 12

oxides of group 2A properties.

Answer 12

form basic solution.

melt at higher temperatures.

Question 13

valance electron configuration.

Answer 13

ns^2

Question 14

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

Answer 14

beryllium

Question 15

properties of beryllium.

Answer 15

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

Question 16

uses of beryllium

Answer 16

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

Question 17

why is beryllium used in rockets and space crafts?

Answer 17

because of its light weight and strength

Question 18

sources of beryllium?

Answer 18

bertrandite

beryl

Question 19

bertrandite chemical formula

Answer 19

Be4S2O7(OH)2

Question 20

beryl chemical formula and colors?

Answer 20

Be3Al2Si6O18

aquamarine
emerald

Question 21

why causes the emerald color in beryl?

Answer 21

contaminated by Cr(III)

Question 22

sources of magniesium?

Answer 22

common in sea water

mineral in nature

Question 23

occurrence of magnesium

Answer 23

carnallite, dolomite epsomite, electrolysis of molten MgCl2

Question 24

carnallite chemical formula

Answer 24

KCl.MgCl2.6H2O

Question 25

dolomite chemical formula

Answer 25

MgCO3.CaCO3

Question 26

epsomite chemical formula

Answer 26

MgSO4.7H2O

Question 27

source of radium

Answer 27

radioactive decay of heavier elements.

Question 28

extraction of 2A group in general

Answer 28

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

Question 29

the chemical formula for electrolysis of molten chlorides

Answer 29

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

Question 30

the chemical formula for the extraction of Mg from seawater.

Answer 30

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

Question 31

extraction of Be from Beryl formula.

Answer 31

beryl + Na2SiF6 -[heat]-> BeF2 (aq) + Be(OH)2 (s) - reduction of BeF2 - electrolysis of BeCl2

Question 32

extraction of Ca

Answer 32

electrolysis of CaCl2 and CaF2

Question 33

extraction of Strotrium and barium

Answer 33

- reduction of corresponding oxides by Al | - electrolysis of MCl2

Question 34

uses of magnesium

Answer 34

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.

Question 35

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

Answer 35

due to its low density.

Question 36

why is Mg essential to plant life?

Answer 36

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

Question 37

Ca occurrence

Answer 37

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

Question 38

marble chemical formula.

Answer 38

CaCO3

Question 39

dolomite chemical formula.

Answer 39

CaCO3.MgCO3

Question 40

gypsum chemical formula.

Answer 40

CaSO4.2H2O

Question 41

fluorite chemical formula.

Answer 41

CaF

Question 42

why is calcium carbonate important in biology?

Answer 42

dietary supplement, reduces osteoporosis, an antiacid consitutive.

Question 43

what is portland cement composed of?

Answer 43

dicalcium silicate, tricalcium silicate, tricalcium aluminate.

Question 44

extraction of Ca from CaCO3

Answer 44

CaCO3 + 2 HCl -> CaCl2 + H2O + CO2 | electrolysis of CaCl2

Question 45

calcium uses.

Answer 45

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

Question 46

flame test results for Ca, Sr, Br

Answer 46

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

Question 46

flame test results for Ca, Sr, Br

Answer 46

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

Question 47

chemical reaction with oxygen

Answer 47

forms oxides.

Question 48

chemical reaction with water

Answer 48

forms dihydrogen gas.

Question 49

chemical reaction with halogens.

Answer 49

forms ionic halides.

Question 50

chemical reaction with dihydrogen

Answer 50

forms hydrides.

Question 51

chemical reaction with nitrogen

Answer 51

forms ionic nitrides

Question 52

chemical reaction with oxides

Answer 52

basic medium (except BeO)

Question 53

chemical reaction with carbonates

Answer 53

goes through thermal decomposition.

Question 54

limestone + heat

Answer 54

makes lime

Question 55

slaked lime reacts with carbon dioxide to make.

Answer 55

limestone.

Question 56

BaO2 + 2H2O -> .....

Answer 56

H2O2 + Ba(OH)2