Term 1 - What I've Learnt

In Term 1, we learned Chemistry, about elements and compounds. I learned that an element is a substance that cannot be broken down into simpler substances by chemical methods. There are currently 118 known elements. A periodic table which lists all the elements exists to make life easier for us. Elements with similar properties are placed in the same group or column. Every element has a name and symbol. For example, the first element is called Hydrogen and its symbol is H.

Elements consist of a particular type of atom. The atoms of one element are different from the atoms of any other element. An atom is the smallest unit of an element, having the properties of that element.

Most substances on earth occur as compounds and not elements. A compound is a substance containing two or more elements chemically joined together. When elements combine to form compounds, heat is usually given out.

Compounds are made up of molecules and ions. The atoms in molecules must be of different kinds. For example, water is made from the elements hydrogen and oxygen.

Ions are atoms that have an electrical charge.

Mixtures are two or more substances that are not chemically joined together. The difference between compounds and mixtures is that compounds have fixed melting and boiling points, its own physical and chemical properties which are different from the elements that it was formed from and cannot be separated into two or more other substances by physical means. Mixtures, however, have variable melting and boiling points and usually has the same properties as it components and it can be easily separated into its components by physical means.