Atoms,elements and the Periodic Table
Many scientists worked to organise elements into patterns based on their properties.
Atoms contain protons,neutrons and electrons.
The number of each can be worked out using the proton number and the atomic mass of the element.
proton have +charge ,and a mass 1
electron have -charge,and a mass of almost zero
neutron have 0 charge and a mass of 1
Number of protons + Number of neutrons =relative atomic mass
Mendeleev's ideas formed the basis for the modern Periodic Table.
Mendeleev arranged elements in to groups (vertical columns) and periods (horizontal rows) based on their relative atomic masses and patterns in their properties.
Scientists rejected Dobereiner's triads and Newlands' octaves because most elements did not fit their 'patterns'
However,when new elements were discovered they fitted Mendeleev's predictions.
When elements are heated up they emit coloured flames.
Each element has a unique flame test colour and line spectrum.
We use the pattern of lines in a line spectrum to identify an element.
Electrons,and the Periodic Table
Electrons are arranged in shells around the nucleus and can be shown using electron arrangements
EACH SHELL HOLDS A MAXIMUM NUMBER OF ELECTRONS.
A period is a row across the periodic table.
There are trends in properties from the left to right, e.g…