Atomic Structure

ATOM Smallest unit of matter An element is made up of the same atom ex: Gold (element on P.T) is made up of gold atoms

Parts of an Atom Atoms are made up of: Protons (p+): Positive charged Electrons (e-) : negatively charged Neutrons (no): no charge (neutral) These are called subatomic particles

Nucleus is found in the centre of the atom The two subatomic particles found in the nucleus are _________________ and ______________ Shells (orbitals) are rings around the nucleus ___________________ are located in the shells outside the nucleus. PROTONS NEUTRONS ELECTRONS

VALENCE SHELL VALENCE SHELL: outer most shell Electrons found in the valence shell are called valence electrons

Determining number of protons, electrons and neutrons... # protons = ATOMIC NUMBER # electrons = # protons (in a neutral atom) # neutrons = ATOMIC MASS – ATOMIC NUMBER

EXAMPLE: Oxygen atomic number = 6 Atomic mass= 16.00 # p= # e= # n= 6 6 16 – 6 = 10

Drawing Bohr-Rutherford Diagrams Draw a circle representing the nucleus Draw orbitals (dotted circles) around the nucleus Hint: the period tells you how many orbitals to draw In the nucleus, indicate how many protons (p+) and neutrons (n0) Fill in the electrons on the orbitals 1st orbital: 2e- 2nd, 3rd, 4th, 5th, orbital – 8 e-

Let’s do an example!