1. 4 ?
. :
25Mn 1s22s22p6 3s23p63d54s2
35Br 1s22s22p6 3s23p6 3d10 4s24p5
d- VIIB , p- VIIA . , . , , , . .
, , , , , .
, , , , . , d- , . , .
2. - ? ()?
. , . : , , . () , - - :
- D + + -
- D - + +
, , . ():
()n D n+ + n-; nn D n+ + nn-
, .
.
: 24Cr - 3d54s1.
: Cr+2O, Cr2+3O3, Cr+6O3, :
Cr+2 (OH)2, Cr+3 (OH)3, H2Cr+6 O4 H2Cr+62 O7.
CrO Cr(OH)2 , r2O3 Cr(OH)3
, CrO3, H2CrO4 H2Cr2O7 .
:
Cr(OH)3 + 3NaOH = Na3[Cr(OH)6]; Cr(OH)3 + 3OH- = [Cr(OH)6]3-.
Cr(OH)3 .
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Cr(OH)3 + 3HCl = CrCl3 + 3H2, Cr(OH)3 + 3H+ = Cr3+ + 3H2O.
Cr(OH)3 .
3. 14 .
. 14 III , IV . . :
14Si 1s22s22p63s23p2,
3s23p2. -. 2ē -, +2 ( SiO), 2ē S-, +4 SiO2, H2SiO3. , SiH4, 4, - , , , 8- .
4. ( 99).
. Z N. Z , , 43.
A = Z + N
: Z = 43 , a N = 99 43 = 56 .