degree symbol

For the degree symbol:

1.  Make sure the Num Lock key is pressed on your keypad 
2. Hold down the ALT key
3.  On the keypad, type the four numbers 0,1,7,6 in succession 
4. Release the ALT key

Draw allenes with central carbon atom as a dot

Using Chem Draw

1. Draw an allene  
2. Right-click on the central carbon and choose Edit Label.
3. Type a bullet character (Alt-0149) . 

Using ChemSketch


Using Marvin Draw