Isabelli, a couple of interrelated interesting questions. I asked my team to prepare the scene …be back later.
First a little experiment. Put a small amount of water into a saucepan and place it on a heat source (parental permission required) carefully observe what happens (observation is an incredibly important science skill). Make notes of what you see. when the water is obviously boiling switch off the heat source and leave the water to cool down. Avoid moving it. Now repeat the experiment, again making notes on your observations. Are there any differences?
Look at the water molecules in the diagrams above. Water is a dipolar liquid. That means that there is an uneven charge distribution in each molecule. It has a negative ‘end’ and a positive ‘end’. This gives it the capability of making the Oxygen molecules (which are not normally dipolar) dipolar and subsequently creates an attractive force between the water and Oxygen molecule (bit like two magnets). The Oxygen molecules like this arrangement and are held within the water structure.
But …. if you heat up the water the water molecules begin to move about faster so the tentative attraction between the water molecule and the oxygen molecule breaks and it escapes from the water. Can this explain what you observed when you heated the water?
Thanks for your comment. Please feel free to ask further questions and make further comments.