Question

Atomic mass of first 20 elements rounded

Answer 1

hey mate!

atomic masses of the first 20 elements are:
hydrogen-1
helium-4
lithium-7
berelium-9
boron-11
carbon-12
nitrogen-14
oxygen-16
fluorine-19
neon-20
sodium-23
magnesium-24
aluminium-27
silicon-28
Phosphorus-31
solicon-32
chlorine-35.5
argon-40
potassium-39
calcium-40


hope it helps!!

Answer 2

We need to give the atomic mass of the first 20elements after rounding them

• So first let us write down the different masses of atoms
• Hydrogen  $1.008$ which can be rounded to $1.01$
• Helium     $4.0026$ which can be rounded to $4.00$
• Lithium.     6.94            
• Beryllium.   $9.0122$ which can be rounded to $9.01$
• Boron.          $10.81$
• Carbon.        $12.001$ which can be rounded to 12.00
• Nitrogen.      $14.007$ which can be rounded to $14.01$
• oxygen.        $15.999$ which can be rounded to $16$
• Fluorine        $18.998$ which can be rounded to $19$
• Neon.             $20.18$
• Sodium.          $22.99$
• Magnesium.   $24.305$ which can be rounded to $24.31$
• Aluminum.      $26.982$ which can be rounded to $26.98$
• Silicon.            $28.085$ which can be rounded to $28.09$
• Phosphorus.    $30.974$ which can be rounded to $30.97$
• Sulfur.                 $32.06$
• Chlorine.          $35.4532$ which can be rounded to $35.45$
• Argon.                  $39.948$ which can be rounded to$39.95$
• Potassium.          $39.098$ which can be rounded to $39.10$
• Calcium              $40.078$ which can be rounded to $40.08$
• The atomic mass of an element can be defined as the average mass of atoms measured in atomic mass units.
• The above atomic mass has been rounded to two decimal points.