Atoms Elements Molecules and Compounds


Atoms make up all matter around us, they are the smallest part of all things. Atoms in the periodic table all have different numbers of protons and are known as elements and they can be combined to make compounds and molecules

Atoms are fundamental particles that make up all matter but when combined in different ways they can be called different things. We have already covered that a group of atoms with the same number of protons are elements.

Molecules are a group of atoms that are bonded together that have the same number of protons. When two atoms of the same element are bonded together this is known as a molecule. An example of a molecule would be chlorine, chlorine has two elements bonded together in a pair.

A compound is a bonded group of elements that are different from each other that are bonded together. When they are bonded they are chemically joined together by sharing or transferring electrons. This movement of electrons causes ions to formed that are attracted to each other, or the sharing of electrons causes the formation of compounds.

It is the interaction of atoms through bonding that leads to the construction of larger molecules and compounds. Non-metallic and metallic elements have different ways of combining to produce new chemicals. For more information on this see the bonding section below.

Elements are defined as particles with the same number of protons. But when combined elements bond to each other in different ways, they produce compounds. Compounds are created when one or more elements chemically bond together. This usually happens by the sharing or transferring of electrons, the nuclei of the relative elements remain unchanged.

A common example of a familiar compound is water, H2O. Water is formed from 2 hydrogen atoms and one oxygen atom. The hydrogen atoms and oxygen atoms share electrons and form a covalent bond.

Another example you may be familiar with is salt made up of the elements sodium and chlorine to form the compound sodium chloride. In this compound the atoms don’t share electrons they transfer them. Sodium gives an electron to Chlorine. This causes Sodium to become positively charged and Chlorine to become negatively charged. This change in charges means they are now attracted to each other.

Other compounds and elements you may be familiar with make up important items in our everyday lives. In most mobile phones copper, gold an silver are used in wiring and components, where as cobalt and lithium are used in the battery. Laptops for example are mainly made of plastics, containing carbon and hydrogen in compounds. Laptop batteries contain lithium and cobalt. Copper and silicon are primarily used in their electrical components. But you may be more familiar with chemicals around the house the elements sodium and chlorine are bonded together to make sodium chloride which is everyday salt that you can put on food.

Terms in section

A proton is a positive particle that makes up the atom in the nucleus with a positive charge


A neutron is a neutral sub atomic particle that makes up the nucleus with the proton


An ion forms when an atom loses or gains electrons to form a positive or negative particles due to the unbalanced number of protons


An atom is the smallest particle that makes up all matter

Covalent bond

A covalent bond forms when two or more atoms share a pair of electrons to form a bond


Metallic elements have metallic bonding and are located on the left hand side and in the middle of the periodic table

Non metallic

Non metallic elements are located on the right hand side of the periodic table with covalent bonding


A molecule is a pair of elements with the same number of protons bonded together


A compound is when two or more elements are joined together by a bond which forms when they share electrons or move them between each other


Elements are atoms with the same number of protons in the nucleus


Metallurgy – the Study of Metallic Elements


An Overview of Bonding