Light 'Em Up, Up, Up

Aim:
To see how much magnesium's weight will change after being turned to ash.

Hypothesis: 

I believe that the magnesium will not change weight.

Equipment:
Heat mat,
Bunsen burner,
Scissor Tongs,
Beakers,
Scales,
Magnesium,
Safety glasses. 
Lighter,

Method:
If you were looking to do this experiment (which I don't recommend to do at home), take some notes.

1. Collect and set up your heating equipment and take whatever precautions necessary (tying up your hair, wearing safety glasses etc.)
2. Weigh a strip of magnesium (or whatever magnesium you have) in a beaker, note. This is so that when you weigh it in the beaker afterwards, the weight will be fair and accurate.
3. Light your bunsen burner, a bunsen burner is of no use when it's not lit.
4. Taking your magnesium in your scissor tongs, CAREFULLY place your magnesium in the middle of the flame (where the small bright blue flame is). 
5. Wait for the metal to set fire. In which you need to not be a scaredy cat like the majority of my group doing this and actually hold the metal in the flame.
6. Once the magnesium sets fire, be careful or you may be blinded(not really but be careful anyway), wait for it to turn to ash and dump the ash into the same beaker that you measured the full magnesium in.
7. All of the magnesium might not burn in one act, so repeat steps 4-6 until all of the magnesium is ash
8. Get all of the ash you can into the beaker, it's alright if you can't, it's just that the result might not be completely accurate to what is meant to happen.
9. Weigh the ash in the beaker and take note of this number.
10. Compare the two numbers to confirm or deny your hypothesis.

Results:

When Brianna, Chyna, and I did this, our starting weight was 4958 milligrams. After the process, we managed to get the majority of the ash into the beaker, but we must've missed some, as our final weight was 4952. Though I did prove my hypothesis wrong, the results were not exactly what should've happened.
I probably should put this in my discussion but the results aren't accurate because, in theory, the weight should have gone up. This is because you're taking oxygen and adding it to the magnesium, which each have separate weights. It's like if oxygen was 2 grams and magnesium was 5 grams, the compound, magnesium oxide should be 7 grams.

Discussions with Sam:

I hope you're ready for some science. In year 10 level words, in this experiment, magnesium reacts with oxygen to create magnesium oxide (Mg + O₂ --> MgO OR 2Mg + O₂ --> 2MgO to balance the equation). But I don't want to settle for a year 10 level as I am a try hard, so let's dive a little deeper.

During this experiment, we take 2 atoms of Mg and an O₂ molecule to create 2 MgO molecules through a chemical reaction. A chemical reaction is a transfer of electrons. Because Mg has 2 electrons in its outer shell, it wants to lose 2 electrons so it becomes stable. A similar thing is happening with O, it has 6 electrons in its outer shell so it wants to gain 2 electrons to become stable. This leaves us with Mg with a charge of 2+ and O with a charge of 2-. Now one has a negative charge and the other has a positive charge, they are "electrostatically" attracted. I'm not sure what this means exactly but my teacher said it once and it sounded smart. I'm kidding, electrostatic attraction is basically just a force that causes positively and negatively charged substances to (H U L K   S M A A A A A S H -Anonymous person *cough* NaTaShA *cough*, 2019.) Bond. She means bond :3.