title: Find empty cells in rows of a column | Dataframe pandas
body: <p>My Dataframe has a column named &quot;Teacher&quot; and i want to know in that column the rows that are empty.
  Example:</p>
  <pre><code>print(df[&quot;Teacher&quot;])
  0
  1
  2      Richard
  3
  4      Richard
  Name: Teacher, Length: 5, dtype: object
  </code></pre>
  <p>I know that if i do something like this:</p>
  <pre><code>R = ['R']
  cond = df['Teacher'].str.startswith(tuple(R))
  print(cond)
  </code></pre>
  <p>It prints the rows of that column and tells me in boolean the teacher that starts with the R.</p>
  <pre><code>print(cond)
  0      False
  1      False
  2      True
  3      False
  4      True
  Name: Teacher, Length: 5, dtype: object
  </code></pre>
  <p>I want the same for the empty ones, to return True when its empty and false when its not but dont know how.</p>