What does it mean for an element to have a -1 charge?

1. list three scientific reasons cockroaches may fly.

The chemical formula for emerald is be3al2(sio3)6.an emerald can be decided as

Use the drop-down menus to label each of the following changes p for physical change and c for chemical change. the substance changes to a new substance. the original substance can be recovered. the color changes. gas is produced and given off. the substance changes size, shape, or volume.