Meeting To 10 : Compare and contrast The Elements

Compare And Contrast  The Elements

Elements

An element is a substance consisting of atoms which all have the same number of protons - i.e. the same atomic number.

Elements are chemically the simplest substances and hence cannot be broken down using chemical methods. Elements can only be changed into other elements using nuclear methods.

Although an element's atoms must all have the same number of protons, they can have different numbers of neutrons and hence different masses. When atoms of the same element have different numbers of neutrons, they are called isotopes.

Element Names and Numbers

All of the elements have been named. Some of these names are familiar to us, such as nitrogen and sodium, and some are less familiar, such as dysprosium and roentgenium.

We can also name elements using their atomic numbers. For example, element 1 is hydrogen, element 2 is helium, element 3 is lithium, element 8 is oxygen, etc.

Many Elements 

There are currently 115 accepted elements and three elements whose existence has been claimed, but not yet accepted (elements 113, 115 and 118).

We use the periodic table to display all of the elements in an organized way.

Elements Ancient and Modern

Some elements have been known for thousands of years, and we do not know who discovered them. These are: antimony, arsenic, carbon, copper, iron, gold, lead, mercury, silver, sulfur, and tin.

All other elements have been discovered since 1669; it was in this year that Hennig Brand became the first named person to discover a new element - phosphorus.

Combining Elements

An element can combine with one or more other elements to form compounds, of which there are millions. For example, one of the best known compounds is water, written chemically as H₂0, which means that water is made of two atoms of hydrogen combined with one of oxygen.