The Atom, Standard Notation and Bohr-Rutherford Diagrams Grade 10 Academic Science Cardinal Ambrozic C.S.S.

The Atom LOCATION Electron Proton Neutron ORBITS Maximum number of electrons in the 1st orbit/ shell is 2 Maximum number of elecrons in the 2nd and 3rd orbit/shell is 8 NUCLEUS This is where most of the mass is Electron (negatively charged) Proton (positively charged) This is obviously a false assumption. We now know through experimental evidence that matter is composed of atoms Neutron (neutral: no charge)

Orbits around the nucleus Subatomic Particles Subatomic Particle Symbol Charge Relative Size Relative Mass Location Proton p+ +1 Large 1 Nucleus Neutron n0 Electron e- -1 Very Small Orbits around the nucleus This is obviously a false assumption. We now know through experimental evidence that matter is composed of atoms

Standard Atomic Notation The atomic structure of an element may be represented by the following notation: Mass Number (Rounded Atomic Mass) Z X Element Symbol A This is obviously a false assumption. We now know through experimental evidence that matter is composed of atoms Atomic Number

Formulas to use when Drawing Atoms ATOMIC NUMBER # of PROTONS = This is also equal to the number of electrons in a NEUTRAL atom. Therefore, ATOMIC NUMBER = # of PROTONS = # of ELECTRONS MASS NUMBER (rounded Atomic Mass) # of PROTONS # of NEUTRONS This is obviously a false assumption. We now know through experimental evidence that matter is composed of atoms = + Therefore the number of neutrons is? # of NEUTRONS = MASS NUMBER - # of PROTONS

Example Questions 1. In standard notation, nitrogen would be written as: How many protons, neutrons and electrons does nitrogen have? 2. In standard notation, sodium would be written as: How many protons, neutrons and electrons does sodium have? This is obviously a false assumption. We now know through experimental evidence that matter is composed of atoms

Information from the Periodic Table This is obviously a false assumption. We now know through experimental evidence that matter is composed of atoms Remember that the mass number is the atomic mass rounded to the nearest whole number

Example Problem 3 Element Name Element Symbol Atomic Number Atomic Mass Mass Number Standard Notation # of Protons # of Electrons # of Neutrons This is obviously a false assumption. We now know through experimental evidence that matter is composed of atoms

Al K S Example Problem 3 Al 13 27 14 K 19 39 20 S 16 32 26.98 39.10 Element Name Element Symbol Atomic Number Atomic Mass Mass Number Standard Notation # of Protons # of Electrons # of Neutrons Aluminum Al 13 26.98 27 14 Potassium K 19 39.10 39 20 Sulfur S 16 32.07 32 27 Al 13 39 K 19 This is obviously a false assumption. We now know through experimental evidence that matter is composed of atoms 32 S 16

Bohr-Rutherford Diagrams Using Bohr-Rutherford diagrams is a useful way of representing the first 20 elements. Draw the Bohr- Rutherford diagram for Lithium and Chlorine. Before you begin, write each element in standard notation. Questions: How many orbits does each of the above elements have? What is the period number (row in the periodic table) for each of the above elements? This is obviously a false assumption. We now know through experimental evidence that matter is composed of atoms