Here's the Code:

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

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Z

Y

X

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V

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T

S

R

Q

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O

N

M

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K

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I

H

G

F

E

D

C

B

A

And the Secret Message:

What holds the elements?
 

A                        PE R IODIC                             TABLE                      HOLDS                      THE
________________________________________________________________________________________
  Z                  K  V  I   R   L   W   R   X           G   Z   Y   O   V         S   L   O   W   H          G   S   V
        ELEMENTS
________________________
 V  O  V   N   V   M   G   H