"Read" the column header "Element" and perform calculation

Hello VBA Gurus,

I get outputs from a program that gives me values in mol but I want mg.
The column headers could be any order and any length and contain red-herrings (things that are not elements).
I am trying to build a macro that searches the column header, identifies which element (if any) it refers to, then performs the appropriate conversion to all the values in that column (which may be of any length), then moves on to the next column.

I have a collection of the elements and their atomic masses but I am stuck in the weeds manipulating collections and arrays.

Attached is example input file.

I want to multiply each value in the column by the corresponding atomic mass and then by 1000.

Here is my code (I haven't got very far!):

Sub elementLookup()

Dim rngElementHeader As Range
Dim rngHeaders As Range
Dim Element As String
Set rngHeaders = Range("1:1")
Set rngElementHeader = rngHeaders.Find(Element)
Dim x As Long, y As Long
Elements = Array("H", "He", "Li", "Be", "B", "C", "N", "O", "F", "Ne", "Na", "Mg", "Al", "Si", "P", "S", "Cl", "Ar", "K", "Ca", "Sc", "Ti", "V", "Cr", "Mn", "Fe", "Co", "Ni", "Cu", "Zn", "Ga", "Ge", "As", "Se", "Br", "Kr", "Rb", "Sr", "Y", "Zr", "Nb", "Mo", "Ru", "Rh", "Pd", "Ag", "Cd", "In", "Sn", "Sb", "Te", "I", "Xe", "Cs", "Ba", "La", "Ce", "Pr", "Nd", "Sm", "Eu", "Gd", "Tb", "Dy", "Ho", "Er", "Tm", "Yb", "Lu", "Hf", "Ta", "W", "Re", "Os", "Ir", "Pt", "Au", "Hg", "Tl", "Pb", "Bi")


For Each Element In Elements

x = Rows(1).Find(Element, LookIn:=xlValues, lookat:=xlWhole).Column
currentelementmass = c.Item(Element)

Dim c As Collection

Set c = New Collection

c.Add "1.00794", "H"
c.Add "4.002602", "He"
c.Add "6.941", "Li"
c.Add "9.012182", "Be"
c.Add "10.811", "B"
c.Add "12.011", "C"
c.Add "14.00674", "N"
c.Add "15.9994", "O"
c.Add "18.9984032", "F"
c.Add "20.1797", "Ne"
c.Add "22.989768", "Na"
c.Add "24.305", "Mg"
c.Add "26.981539", "Al"
c.Add "28.0855", "Si"
c.Add "30.973762", "P"
c.Add "32.066", "S"
c.Add "35.4527", "Cl"
c.Add "39.948", "Ar"
c.Add "39.0983", "K"
c.Add "40.078", "Ca"
c.Add "44.95591", "Sc"
c.Add "47.88", "Ti"
c.Add "50.9415", "V"
c.Add "51.9961", "Cr"
c.Add "54.93805", "Mn"
c.Add "55.847", "Fe"
c.Add "58.9332", "Co"
c.Add "58.6934", "Ni"
c.Add "63.546", "Cu"
c.Add "65.39", "Zn"
c.Add "69.723", "Ga"
c.Add "72.61", "Ge"
c.Add "74.92159", "As"
c.Add "78.96", "Se"
c.Add "79.904", "Br"
c.Add "83.8", "Kr"
c.Add "85.4678", "Rb"
c.Add "87.62", "Sr"
c.Add "88.90585", "Y"
c.Add "91.224", "Zr"
c.Add "92.90638", "Nb"
c.Add "95.94", "Mo"
c.Add "101.07", "Ru"
c.Add "102.9055", "Rh"
c.Add "106.42", "Pd"
c.Add "107.8682", "Ag"
c.Add "112.411", "Cd"
c.Add "114.818", "In"
c.Add "118.71", "Sn"
c.Add "121.757", "Sb"
c.Add "127.6", "Te"
c.Add "126.90447", "I"
c.Add "131.29", "Xe"
c.Add "132.90543", "Cs"
c.Add "137.327", "Ba"
c.Add "138.9055", "La"
c.Add "140.115", "Ce"
c.Add "140.90765", "Pr"
c.Add "144.24", "Nd"
c.Add "150.36", "Sm"
c.Add "151.965", "Eu"
c.Add "157.25", "Gd"
c.Add "158.92534", "Tb"
c.Add "162.5", "Dy"
c.Add "164.93032", "Ho"
c.Add "167.26", "Er"
c.Add "168.93421", "Tm"
c.Add "173.04", "Yb"
c.Add "174.967", "Lu"
c.Add "178.49", "Hf"
c.Add "180.9479", "Ta"
c.Add "183.84", "W"
c.Add "186.207", "Re"
c.Add "190.23", "Os"
c.Add "192.22", "Ir"
c.Add "195.08", "Pt"
c.Add "196.96654", "Au"
c.Add "200.59", "Hg"
c.Add "204.3833", "Tl"
c.Add "207.2", "Pb"
c.Add "208.98037", "Bi"




End Sub

Thanks in advance, I have been using this site for a long time and it's a great thing!