Which of the following is not a reason why chemical bonds are important

B. Building and breaking bonds are part of the energy cycle

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water

Both models are effective because they show the valence electrons, and these valence electrons indicate the reactivity of an element.