ELEMENTS AND ISOTOPES

ELEMENTS AND ISOTOPES

1. The periodic table is laid out so that elements with similar properties form colummns.

   • These vertical columns are called groups and roman numerals often are used for them

2. The group to which the element belongs corresponds to the number of electrons it has in its outer shell.

   • Group 1 elemets have 1 outer shell electron, Group 7 elements have 7 outer shell electrons
     • Group 8 elements have 8 electrons in their outer shell,; this means they are stable.

3. The rows are called periods.

   • Each new period represents another full outer shell of electrons.
     • The period to which the element belongs corresponds tot he number of shells of electrons it has.

4. There are around 100 elements, which all materials are made of.

5. The modern periodic table shows the elements in order to ascending atomic number

6. Isotopes are different forms of the same elelment, which have the same number of protons but a different number of electron.s

   • They have the same atomic number but different mass numbers.
     • If they had different atomic numbers then they'd be different elements altogether.
       • An example is Carbon-12 and Carbon-14