ATOMIC STRUCTURE

ATOMIC STRUCTURE

1. Atoms contain three sub-atomic particles called protons, neutrons and electrons.

2. The protons and neutrons are found in the nucleus at the centre of the atom. The nucleus is very much smaller than the atom as a whole. The electrons are arranged in shells around the nucleus.

3. REALATIVE MASS

   • PROTON = 1
   • NEUTRON = 1
   • ELECTRON = 1/1836

4. CHARGES

   • PROTON = +1
   • NEUTRON = 0
   • ELECTRON = -1

5. if an atom loses one or more electrons, it becomes a positively charged ion if an atom gains one or more electrons, it becomes a negatively charged ion

6. Isotopes are atoms of an element with the normal number of protons and electrons, but different numbers of neutrons. Isotopes have the same atomic number, but different mass numbers.

7. Different atoms have different masses. Atoms have such a small mass it is more convenient to know their masses compared to each other. Carbon is taken as the standard atom and has a relative atomic mass (Ar) of 12.

   • Atoms with an Ar of less than this have a smaller mass than a carbon atom.
   • Atoms with an Ar that is more than this have a larger mass than a carbon atom.

8. The periodic table has eight main groups. For example, Group 1 contains very reactive metals such as sodium (Na), while Group 7 contains very reactive non-metals such as chlorine (Cl).

9. ATOMIC NUMBER- IS THE SMALLER NUMBER. IT IS THE NUMBER OF PROTONS

10. MASS NUMBER- THE BIGGER NUMBER OF THE ELEMENT INDICATING THE TOTAL NUMBER OF PROTONS AND NEUTRONS

11. ISOTOPE- DIFFERENT ATOMS OF THE SAME ELEMENT WITH DIFFERENT NUMBER OF NEUTRONS ADN SAME NUMBEWR OF PROTONS

12. MOL- measuring large quantities of very small entities such as atoms, molecules,