df3['Coefficient of linear thermal expansion']=df3['Coefficient of linear thermal expansion'].str.replace(r"(?:no data)|(?: x10<sup>-6</sup>K<sup>-1</sup>)",'')
# ### Lastly fill the empty features with np.nan values
# In[10]:
df_clean=df4.replace(r'^\s*$',np.nan,regex=True)
# In[11]:
df_clean;
# # Section instantiation and its objects attributes are filled. This will create 118 objects unique ( atomic element symbol) which can be used to access its properties