Atomic Structure

Atomic Structure

1. Inside every atom;

   • NUCLEUS containing PROTON and NEUTRON both NUCLEONS
   • Orbiting this core are the ELECTRONS
   • PROTON; +1.6 x10-19 C, 1.67x10-27 Kg, Charge +1, Mass 1
   • NEUTRON; 0 C, 1.67X10-27 Kg, Charge 0, Mass 1
   • ELECTRON; -1.6X10-19, 9.11X10-31 Kg, Charge -1, Mass 0.0005

2. The proton number is the number of protons in the nucleus

   • Proton number can be called atomic number. Symbol = Z
   • Its the proton number that defines the element- no 2 elements will have the same number of protons.
   • In a neutral atom the number of electrons equals the number of protons
   • The elements reactions and chemical behaviour depend on the number of electrons

3. The nucleon number is the total number of protons & neutrons

   • Nucleon number can also be called mass number. Symbol = A
   • Shows how many protons and neutrons are in the nucleus
   • The number of nucleons = atoms relative mass

4. Isotopes

   • Have the same proton number, but different nucleon numbers.
   • Atoms with the same number of protons but different numbers of neutrons
   • Changing the number of neutrons doesn't affect the atoms chemical properties
   • The number of neutrons affects the stability of the nucleus
   • Unstable nuclei may be radioactive and decay over time into different more stable nuclei

5. Specific Charge

   • The specific charge of a particle is equal to its charge over mass
   • ratio of charge to its mass. Unit= C Kg -1
   • Example: Calculate the specific charge of a proton. Charge = +1.6x10-19, Mass 1.67x10-27.(1.6x10-19) / (1.67x10-27) = 9.58x107 CKg -1