Structure of the Atom

Bohr- Rutherford Model of Atom

Subatomic ParticleLocationChargeMass Proton NucleusPositive (+)Heavy Neutron NucleusNeutral (0)Heavy Electron Electron Orbit Negative (-)Almost no mass

# of electrons = # of protons – Make the atom neutral Electron shells (orbits) hold only a certain # of electrons: – 1 st shell: 2 electrons – 2 nd shell: 8 electrons – 3 rd shell: 8 electrons

Where do we find this information? Atomic Number: refers to the # of protons in an atom’s nucleus Standard Atomic Notation

Learning Check What is the atomic number for… – Mg – N – Ge – I How many protons does each atom have? – Cu – Li

Learning Check What is the atomic number for… – Mg 12 – N7 – Ge32 – I53 How many protons does each atom have? – Cu29 – Li3

Mass Number: refers to the number of protons and neutrons in an atom’s nucleus Atomic Mass: the mass of an atom in atomic mass units (u) How many NEUTRONS are in a K atom?

Mass Number: refers to the number of protons and neutrons in an atom’s nucleus How many NEUTRONS are in a K atom? Mass # - Atomic # = = 20 Neutrons

Isotopes Has a different # of neutrons for the element’s atom but the # of protons remains the same

** We use the atomic mass (rounded to nearest whole #) as the mass number We use this to figure out the number of neutrons in an atom.

Element Name Atomic Number Mass Number Standard Atomic Notation Number of Protons Number of Electrons Number of Neutrons Aluminum Al Show me what you understand…….

Element Name Atomic Number Mass Number Standard Atomic Notation Number of Protons Number of Electrons Number of Neutrons Aluminum Al