Chemical bonds: ionic and covalent

Ionic compounds have high melting and boiling points, most dissolve in water, and they conduct electricity when dissolved or melted, but not as solids. Covalent compounds often have low melting and boiling points and conduct electricity poorly. Many covalent compounds do not dissolve in water, but some, like sugar, do. Carbon is the key element of organic compounds. It has 4 outer electrons, so it can make four bonds, and its atoms can join to each other in straight chains, branched chains and rings. Methane, CH₄, has one carbon atom joined to four hydrogen atoms by four single bonds. It is the simplest organic molecule. Water is an inorganic compound. Methane burns to give carbon dioxide and water vapour, which is why it is used as a fuel. We only read about this: we never burn gas as an activity.