periodic table + oxidation state + atomic masses,radii,density&chemical activity

Question 1

how many elements are the transitional elements of the periodic table ?

Answer 1

more than 60 elements and they represent more than half the periodic table

Question 2

why does the group vIII contain 3 vertical columns ?

Answer 2

bec. its elements are similar horizontally more than vertically

Question 3

what are the 10 elements that form nearly 7% of the earths crust ?and what are the most abundant three of them ?

Answer 3

scandium , titanium , vanadium , chromium , manganese , iron , cobalt , nickel , copper , zinc / fe>ti>mn

Question 4

what are the two anomalous elements ?

Answer 4

cu , cr

Question 5

what is IP (ionization potential) ?

Answer 5

it is the energy required to lose electrons

Question 6

haw many oxidation states do the representative elements have ? and why ?

Answer 6

one oxidation state / as it is easy to lose electrons from the outermost energy level but harder to lose electrons from the level before as it is completely filled with electrons

Question 7

why do the transition elements have multiple oxidation states ?

Answer 7

this is bec. 4s , 3d sublevels are very close in energy so the atom loses the electrons in 4s sublevel then lose the electrons in 3d gradually

Question 8

why is it that from group VIII to group IIB the oxidation states decrease ?

Answer 8

bec. by increasing the attraction force of nucleus the IP increase , therefore difficulty of removing all electrons from 4s & 3d

Question 9

scandium can only give oxidation state 2+ only why ?

Answer 9

bec. it is easy to lose the three electrons of 4s , 3d at once to get great stability o

Question 10

scandium cant give oxidation level 4+ ?

Answer 10

bec. it is extremely difficult to break a completely filled energy level

Question 11

the maximum oxidation state does not exceed the …

Answer 11

number of its group in the periodic table except for the group IB as it reaches oxidation states 2+ , 3+

Question 12

what are the three cases of stability of the atom (less energy) ?

Answer 12

1) half filled sublevel like d5
2) completely filled sublevel d10
3) great stability of completely filled main level like argon

Question 13

reactions are …. towards the formation of more stable atoms

Answer 13

easier

Question 14

oxidation process means …..

Answer 14

losing electrons & increasing oxidation number

Question 15

reduction process means ……

Answer 15

gaining electrons & decreasing of the oxidation number

Question 16

the element that gain electrons is called ….

Answer 16

oxidizing agent

Question 17

the element that loses electrons is called …..

Answer 17

reducing agent

Question 18

what happens to fe 2+ when left in air ?

Answer 18

it oxidizes to fe 3+

Question 19

what is the definition of transition elements ?

Answer 19

the elements whose d or f sublevel is not completely filled with electrons in either their atomic state or in one of their oxidation states

Question 20

can we consider the coinage metals (group IB) as transition elements ?

Answer 20

yes , bec. although in its atomic state the d sublevel is completely filled with electrons , in its oxidizing states 2+ or 3+ the sublevel d will be incompletely filled

Question 21

can we consider group IIB as transition elements ?

Answer 21

no , bec. the d sublevel is completely filled with electrons in both is atomic and oxidizing state

Question 22

the atomic mass (atomic weight) increases by increasing ……..

Answer 22

the atomic number

Question 23

nickels atomic mass is an abnormal case give reason ?

Answer 23

due to the presence of five stable nickel isotopes their average mass is 58.7

Question 24

what happens to the atomic radii from sc to cr ?

Answer 24

it decrease in very small percentage

Question 25

what happens to the atomic radii from cr to cu ?

Answer 25

it is nearly constant

Question 26

why is the atomic radii nearly constant from cr to cu ?

Answer 26

due to two opposite factors :
1) attraction 2)repulsion
as the atomic number increase as the number of -ve
the +ve & -ve charge increase electrons increase ,
therefore,the attraction force the repulsion force
between them increase which, between them also
decrease the atomic radii increase , therefore
the atomic radius
increase
-the two factors cancel each other which is why tha atomic radius from cr to cu is nearly constant

Question 27

what are the industrial benefit of nearly constant radii of the first transition series ?

Answer 27

the formation of alloys as they are formed by mixing two or more elements that have nearly the same radius

Question 28

the transition elements have high density which increase by increasing …….

Answer 28

the atomic number , as density = mass/volume

since that the volume is nearly constant , the density increase by increasing the mass

Question 29

for making airplane bodies …… density is the best

Answer 29

less

Question 30

chemical activity is the …..

Answer 30

ability of elements to participate in chemical reaction , the higher the chemical activity the faster the reaction

Question 31

the chemical activity decrease by ………

Answer 31

increasing the atomic number or decreasing the radius

Question 32

the atomic volume from sc to cr decrease by ……

Answer 32

increasing the atomic number

Question 33

why does all the elements of the first transition series have high melting and boiling points?

Answer 33

due to the strong metallic bond which is formed by sharing the electrons of 4s &3d

Question 34

the more electrons in 4s &3d the higher the…

Answer 34

conductivity , melting &boiling points