Atoms

Atoms

1. atoms and elements

   • element is a substance only made from one sort of atom
   • atoms consist of electrons surrounding a nucleus that contains protons and neutrons
     • neutrons are neutral, but protons and electrons are electrically charged
       • protons have a relative charge of +1
       • electrons have a relative charge of -1

2. metals&non metals

   • the metals are shown on the left of the periodic table
   • non metals are shown on the right

3. atomic number&mass number

   • atomic number; number of protons
     • number of protons and electrons the same
   • mass number; total number of protons&neutrons
     • you can work out the number of neutrons from the mass number and atomic number. In this example, it is 35 – 17 = 18 neutrons.

4. elements electronic structure

   • Find the element in the periodic table. Work out which period (row) it is in, and draw that number of circles around the nucleus.
     • Work out which group the element is in and draw that number of electrons in the outer circle – with eight for Group 0 elements – except helium.
       • Fill the other circles with as many electrons as needed. Remember – two in the first circle, and eight in the second and third circles.
         • Finally, check that the number of electrons is the same as the atomic number.