C2.1

CHEMICAL BONDING:When different elements react and combine to form a new compound, a chemical bond takes place to keep the atoms together. It will now be difficult to seperate them.Chemical Bond refers to the strong electrical force of attraction between the atoms or ions in the structure.

The atoms can join together by sharing electrons, which is called Covalent Bonding.

Or they can transfer or accept electrons to form  positive or negative ions called an ionic bond.

why do atoms bond together?

Some atoms are very reluctant to combine with other atoms and exist as single atoms. These are called noble gases. This is because their outer shell is full. E.g it has : 2,8,8

Atoms bond together to be more stable and gain electrons so they can be like the Noble gases and have a full outer shell.

Ionic bond= when one atom transfers electrons to another atom to form oppositely charged particles called ions which attract each other.

Ionic bonding is where one atom transfers electrons to another atom to form an oppositley charged particles.

if electrons are lost, it turns positive ion.

If electrons are gained its a negative ion

The charge of the ion is based upon the number of postive or negative electrons lost or gained.

The atom loosing an electron is normally a metal turning it positive.

The atom normally gaining an electron is a non metal as it has a negative charge.

ELEMENTS IN GROUP 1 REACT WITH ALL THE NON METALS TO FORM IONIC COMPOUNDS IN WHICH THE HALIDE COMPOUNDS HAVE A SINGLE NEGATIVE CHARGE.

Covalent bond= when non metals react together they share electrons to form molecules.

Simple molecule:the atoms of non metals generally need to gain electrons to achieve stable outer shells. When they react together neither of the atoms can give away electrons so they get the structure of a noble gas because they can only share electrons. The molecules in the atom are held together because they are sharing electrons.THESE ARE STRONG BONDS.

Giant Structures=They have giant structures where huge number of atoms are held together by a network of covalent bonds.

Diamond is an example of a giant structure. In each carbon atom forms four covalent bonds in a rigid giant covalent structure.

When non metal atoms react together they tend to produce COVALENT bonds. The atoms in these bonds are held together by SHARED electrons. Most substances held together by covalent bonds consist of MOLECULES, but a few have GIANT STRUCTURES.

Metals are another giant structure. Lattice. Arranged in a regular pattern.

The outer electrons in each atom can move easily from one atom to the next one. The outer electrons in the highest occupied energy level form a sea of attraction between the negatively charged electrons and positive charged ions bond the metal ions together.

The sea of electrons are called Delocalised electrons. They help us explain the properties of metals.

The giant structure is not usually the same throughout the metal.  If you look closely, the metal is made up of a number of small crystals.These are called grains and the places where they join are called the grain boundaries.

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Ionic boning

Covalent Bonding- simple

Bonding in metal