The part of the atom which is involved in chemical bonding with other atoms is called Valence Electrons. Hope this helps :)
Ash can be harmful to an environment. It mostly depends on how much ash there is though. If a volcano erupted such as Mt. St. Helen's then yes that can harm an environment. Ash can cover the sky and block out the sun for days before disappearing and that will affect the life of plants
Skin serves as a protective barrier, a way to sense the world, and a layer that keeps nutrients and water inside the body. Four types of cells make up the skin, and they are produced mainly in the epidermis near the basement membrane.
The immune system protects the body from possibly harmful substances by recognizing and responding to antigens.
