Atoms of oxygen are electronegative and attract the shared electrons in their covalent bonds.
An example of accurate but not precise would be 3 people weigh a 10g sample. the weights are 0g, 10g, & 20 grams. the scale is way off but the weights average to the right thing.
precise but not accurate would weighing a 10g sample 3 times and getting 5.5, 5.4, & 5.5. they'e all incredibly similar therefore precise but its nowhere near 10, so not accurate.
neither precise nor accurate would be 3 weights being 10, 20, &30. It averages wrong and is imprecise.
