Atomic Structure Bellringer: What is the charge of the following: Protons, Electrons, and neutrons? Objective: SWBAT describe the structure of an atom. SWBAT use atomic # and mass to calculate the # of subatomic partices

ATOMIC STRUCTURE Particle Charge proton + charge neutron No charge electron - charge

HELIUM ATOM + - + - Shell proton neutron electron What do these particles consist of?

ATOMIC STRUCTURE Particle Charge Mass proton 1 neutron 1 electron nil + (positive) charge neutron No charge 1 - (Negative) charge electron nil

Atomic Mass Units We use Atomic Mass Units (amu) to measure the mass of atomic particles. 1 amu = 1.660538921(73)×10−27 kg 0.000000000000000000000000001660538921 kg

Goal: Draw a Bohr Model of an Atom Steps: Determine the number of protons, neutrons, and electrons. Draw nucleus with protons and neutrons Draw electrons in proper orbitals We use the Bohr model because it’s the only good way to represent an atom and it’s electrons on paper.

Step 1: Determine the number of protons, neutrons, and electrons How do we know how many protons, neutrons, and electrons an atom of an element has?

He 2 4 ATOMIC STRUCTURE number of electrons = number of protons Atomic number the number of protons in an atom 4 Atomic mass the number of protons and neutrons in an atom number of electrons = number of protons Atomic Mass – Atomic Number = # or Neutrons

Guided Practice: H: Hydrogen Atomic Number = _____ ATOMIC STRUCTURE Guided Practice: H: Hydrogen Atomic Number = _____ # of protons = _____ # of electrons = _____ Atomic Mass = _____ # of neutrons = ____ 1 1 1 1

Guided Practice: He: Helium Atomic Number = _____ # of protons = _____ ATOMIC STRUCTURE Guided Practice: He: Helium Atomic Number = _____ # of protons = _____ # of electrons = _____ Atomic Mass = _____ # of neutrons = ____ 2 2 2 4 2

Guided Practice: Li: Lithium Atomic Number = _____ ATOMIC STRUCTURE Guided Practice: Li: Lithium Atomic Number = _____ # of protons = _____ # of electrons = _____ Atomic Mass = _____ # of neutrons = ____ 3 3 3 7 4

Or + = + = Step 2: Draw nucleus with protons and neutrons He:

Guided Practice H: Protons = 1 Neutrons = 0 P = 1 N = 0 + Or

= + = + = + = Or Guided Practice Li: Protons = 3 Neutrons = 4 P = 3

How do we know where to put the electrons? Step 3: Draw the electons in the electron orbitals How do we know where to put the electrons?

Fill up the lowest orbital before moving to next!! Electrons are arranged in Energy Levels or Shells around the nucleus of an atom. first shell a maximum of 2 electrons second shell a maximum of 8 electrons third shell a maximum of 8 electrons fourth shell a maximum of 18 electrons fifth shell a maximum of 18 electrons sixth shell a maximum of 32 electrons Fill up the lowest orbital before moving to next!!

Or + = + = Step 3: Draw electrons in electron in orbitals - - He:

Guided Practice - - H: Electrons = 1 P = 1 N = 0 + Or

= + = + = + = Or Guided Practice - Li: Electrons = 3 - - - - - P = 3

Assigned Practice Due tomorrow!!