A generator because they connect each other in physical attraction
A water molecule consists of three atoms; an oxygen atom and two hydrogen atoms, which are bond together like little magnets.
An iron pot is made up of only one substance, iron. Iron is an element classified as a transition metal
Iron. Elementsare pure substances that are made up of one kind of atom. Pizza is not an element because it is a mixture of many substances. Water is a pure substance, but it contains two kindsof atom: oxygen and hydrogen.
It's called simple diffusion, the small molecules without charges such as oxygen and carbon dioxide can flow through a plasma membrane without assistance and without expending energy. Other substances such as proteins, glucose and charged particles called ions cannot pass through the selectively permeable membrane.