Atomic Structure and the Periodic Table

Atomic Structure and the Periodic Table

1. Atoms

   • Structure of an Atom
     • Atoms have a radius of around 0.1 nanometres (1 x 10^-10 metres)
     • Nuclear Model
       • The nucleus is in the middle of the atom and it contains the PROTONS and NEUTRONS. Proton have a positive charge, neutrons have no overall charge. Therefore, the overall charge of the nucleus is positive.
       • The ELECTRONS move around the nucleus. They occupy different shells around the nucleus.
       • PROTONS
         • Relative Charge = +1
         • Relative Mass = 1
       • NEUTRONS
         • Relative Charge = 0
         • Relative Mass = 1
       • ELECTRONS
         • Relative Charge = -1
         • Relative Mass = 1/1836
   • Electrical Charge
     • In an atom, the number of protons equals the number of electrons. Therefore, the overall charge of the atom is neutral.
     • If some electrons are added or removed, the atom becomes either positively or negatively charged and becomes an ION.
       • ION - an atom or a group of atoms that have lost or gained electrons

2. Elements

   • The number of protons in an atom determines what type of atom it is.
   • Element - a substance made up of only one type of atom
   • Nuclear Symblos
     • Nuclear Symbol - the chemical symbol of the atom with the atomic number (bottom) and mass number (top) by it.
     • The mass number and the proton number can be used to work out the number of protons, neutrons and electron in the atom.

3. Isotopes

   • Isotope - different forms of the same element, which have the same number of protons, but a different number of neutrons.
   • Relative Atomic Mass
     • Many elements have more than one isotope. This means when referring to masses of elements, RELATIVE ATOMIC MASS is used.
     • RELATIVE ATOMIC MASS - the average mass taking into account the different masses of the isotopes that make up the element, and how abundant each isotope is.
     • Relative Atomic Mass = (sum of (isotope abundance x isotope mass number)) / sum of abundances of all isotopes

4. Compounds

   • COMPOUND - a substance made up of two or more types of atmos, chemically bonded together
   • How do Compounds Fform?

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