Structure of the Atom Bohr Rutherford Model of

Structure of the Atom

Bohr- Rutherford Model of Atom

Subatomic Particle Location Charge Mass Proton Nucleus Positive (+) Heavy Neutron Nucleus Neutral (0) Heavy 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? Standard Atomic Notation • Atomic Number: refers to the # of protons in an atom’s nucleus

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 –N – Ge –I 12 7 32 53 • How many protons does each atom have? – Cu – Li 29 3

• 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 # = 39 -19 = 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 Electrons Neutrons Aluminum 13 27 27 13 13 Al Show me what you understand……. 13 14

Element Name Atomic Number Mass Number Standard Atomic Notation Number of Protons Electrons Neutrons Aluminum 13 27 27 13 13 Al 13 14