What is chemical ties?

Chemical bonds occur when two or more atoms are joined to form a molecule. The general principle in science is that all systems will try to achieve their lowest energy levels and chemical bonds will only take place if the molecule can form, which has less energy than its unpromised atoms. The three main types of binding are ion, covalent and metal. All this includes electrons moving between atoms in different ways. Another, much weaker, type is a hydrogen bond.

Atomic structure

Atoms consist of a core containing a positively charged proton that is surrounded by the same number of negatively charged electrons. Normally they are electrically neutral. However, the atom may lose or get one or more electrons, giving it a positive or negative charge. When a person has an electric charge, it is called the ion.

It is electrons that participate in chemical bindings. These particles are arranged in shells on which to exist ongrowing distances from the core. In general, the further the shells are, the more energy they have. The number of electrons that can occupy the shell is a limit. For example, the first, inner, Shell has a limit of two and other shells and a limit of eight.

In most cases, only electrons in the farthest shell participate in gluing. They are often called valence electrons . In general, atoms will tend to combine each other in such a way that everyone achieves full outer shells, because these configurations usually have less energy. A group of elements known as noble gases - helium, neon, argon, krypton, xenon and radon - already have full outer shells and therefore usually do not form chemical ties. Other elements generally try to achieve the structure of noble gas by giving, accepting or sharing electrons with other atoms.

Chemical bonds are sometimes replacedpresented by something called Structure Lewis, named after American chemist Gilbert N. Lewis. In the Lewis structure, valence electrons are represented by dots just outside the chemical symbols for elements in the molecule. They clearly show where the electrons moved from one atom to the other and where they are shared between atoms.

ion binding

For this type of chemical bond, there is a metals that easily give up electrons and non -acts that want to accept them. The metal gives electrons in its incomplete furthest shell Nekol and leaves this shell empty so that the full shell under it becomes a new outer shell. He accepts the electrons to fill his incomplete outer shell. In this way, both atoms reached a full outer shell. This leaves metal with a positive charge and non -metal with a negative charge, so they are positive and negative ions that attract each other.

A simple example is sodium fluoride. Sodium has three shells, with one ValenčnI eat electron in the farthest. Fluor has two shells, with seven electrons in the furthest. The sodium gives its valence electron atom of the fluorine atom, so the sodium now has two complete shells and a positive charge, while fluorin has two complete shells and negative charges. The resulting molecule - sodium fluoride - contains two atoms with complete outer shells connected together by electric attraction.

covalent binding

Nekol atoms combine each other by sharing electrons in such a way that they reduce the total energy level. This usually means that they have all full outer shells when combined. For a simple example, hydrogen has only one electron, in its first - and only - shell, which leaves it one short from a full shell. Two hydrogen atoms can share their electrons to form a molecule in which they both have full outer shell.

It is often possible to predict how atoms will combine each other from the number of electrons they have. For example, carbon has six, which is knownHe has a full first shell of two and farthest shells for four years, so it is four shortly from a full outer shell. Oxygen has eight, so it has six in its outer shell - two short from a full shell. The carbon atom can be combined with two oxygen atoms to form carbon dioxide, in which carbon shares its four electrons, two with each oxygen atom and oxygen atoms each share two of its electrons with atom of the carbon. In this way, all three atoms have full outer shells containing eight electrons.

metal binding

In a piece of metal, valence electrons are more or less free to move, rather than one of the atoms. Therefore, the metal consists of positively charged ions surrounded by mobile, negatively charged chosenmiron. Ions can be moved relatively easily, but it is difficult to separate them due to their attraction to electrons. This explains why metals are generally easy to bend, but it is difficult to break. Electron mobility also explains why metals are good wiresElectricity.

hydrogen binding

In contrast to the above examples, hydrogen binding includes molecules rather than inside. When hydrogen combines with an element that strongly attracts electrons - such as fluorine or oxygen - electrons are pulled from hydrogen. This results in a molecule with an overall positive charge on one side and a negative charge on the other. In the liquid, positive and negative parties attract each other and create links between molecules.

Although these bonds are much weaker than ionic, covalent or metal bonds, they are very important. Hydrogen binding takes place in water, a compound containing two hydrogen atoms and one zyslík. This means that more energy is needed to convert liquid water into gas than it would be different. Without a hydrogen bond, the water would have a much lower boiling point and could not exist as a liquid on the ground.