Atomic Structure and Reactions

Atomic Structure and Reactions

1. Atomic Structure

   • Electrons
     • Negative charge
     • The number of electrons, in a neutral atom, is the same as the number of protons
   • Protons
     • Positive Charge
     • The number of protons indicates its position on the Periodic Table (or the element)
     • Contributes to the mass of the atom
   • Neutrons
     • Neutral Charge
     • Contributes to the mass of the atom

2. Nomeclature

   • The Chemical Symbol is used to represent the element

3. Atomic and Mass No.

   • The Atomic number is the smaller number and indicates the number of protons (or electrons)
   • The Mass number is the number of protons and neutrons

4. Nucleus

   • The centre of the atom is the nucleus
   • The nucleus contains all the weight (or mass) of the atom
   • Protons and Neutrons are in the nucleus.

5. Electron Shells

   • The electrons move around the nucleus of the atom
   • The are very light and do not contribute to the mass of the atom.
   • The shell’s are named K, L, M and N.

6. Valence Electrons and Electron configuration

   • Valence electrons
     • number of electrons in the outermost shell
   • electron configuration
     • shows the way in which the shells have been filled. It is written as K, L, M, N (where each letter is the number of electrons in the atoms shells)

7. Isotopes

   • Isotopes are atoms of the same element that differ in the number of neutrons in the nucleus
   • This means the number of protons remains the same in all of the isotopes.
   • If the number of protons remains the same – all isotopes have the same atomic number