Atomic Structure

Atomic Structure

1. Atomic number

   • The symbol for atomic number is Z
   • This is the number of protons in the nucleus
   • When an atom is neutrally charged, the atomic will correspond to the number of electrons, because the number of positive charges must be the same as the number of negative charges

2. The structure of atoms

   • Rutherford's nuclear model of the atom contained a nucleus with protons and neutrons and orbiting electrons
   • Protons, electrons and neutrons are called sub -atomic particles.
   • If an atom loses or gains an electron it becomes charged and it is called an ion
   • Substances that contain only one type of atom are called elements.

3. Mass number

   • The mass number symbol is A
   • The mass number is the number of protons and neutrons together.

4. Isotopes

   • Isotopes of an element have the same number of protons but a different number of neutrons
   • All atoms of a particular element contain the same number of protons
   • Isotopes have similar chemical properties because their electron structure is the same
   • Isotopes have different physical properties due to their different mass number

5. Electron configuration and stability

   • The order of filling sub-shells is: 1s2 2s2 2p6 3s2 3p6 4s2 3d10
   • Sub-levels- S holds 2 e. P holds 6 e. D holds 10 e. F holds 14 e.
   • Principal energy levels, K,L,M N
   • atoms will a full outer shell are very stable
   • atoms can gain or lose electrons to achieve a full outer shell
   • atoms can become stable by three ways; giving electrons to another atom, by taking electrons from another atom and by sharing electrons with another atom

6. Chemical bonds

   • Metals and non-metal atoms are joined by ionic bonding
   • The forces between atoms in a chemical bond are electrostatic
   • all substances around us are formed by ions bonding together

7. Types of chemical bond

   • An ionic bond results when metallic atoms combine with non metallic aatoms to form an ionic lattice
   • A metallic bond results when metallic atoms combine to form a metallic lattice
   • A covalent bond results when non-metallic atoms combine to form either molecules or covalent lattice