elements and the periodic table

elements and the periodic table

1. all substances are made of tiny particles called atoms.

   • an element is only made up of one type of that atom.
     • atoms of each element are given a chemical symbol.
       • for example O represents and Oxygen atom

2. the elements and patterns in properties

3. all the elements are arranged in a table called the periodic table

   • each vertical column is called a group.
     • elements in the same group have similar properties.

4. 1869 was when madeleev first made a similar table of elements known then.

   • gaps were left in this early periodic table for scientists who discovered new elements

5. Particles in an atom

   • has a small central nucleus.
     • it contains protons and neutrons.
     • electrons orbit around the nucleus.
   • protons, neutrons and electrons are very small
     • are impossible to weigh
       • we use numbers, atomic mass units, to express their masses relative formula.
   • in an atom, the number of protons=number of electrons=atomic mass number.
     • unique to each element.
     • has no net charge
     • mass number= number of protons + neutrons
     • electrons are arranged in shells.
       • 2 electrons fill the 1st shell
       • 8 electrons fill each shell after

6. bonding

   • only a few elements exists naturally as single atoms
     • two atoms of the same element can join together to create a molecule.