Do Now Work silently. Raise hand to ask Ms. Hughes anything. 1.Describe Thomson’s atomic model. 2.Describe Dalton’s atomic model.

Announcements Unit 3 test next Friday If you have not taken 2 chemistry tests yet this semester, see me after to arrange a make up Also, come in for quick tutoring, then RETAKE GLEs for a GRADE BOOST

Mystery Element #1: Too little of this element in the body causes osteoporosis. #2: You can get this element from drinking milk #3: It is good for your bones!

Numero Cinco! - R. A. Millikan Experiment: Millikan Oil Drop Experiment When: 1909 Where: U.S.A!!!!

Millikan’s Oil Drop Experiment

Millikan! Sprayed oil drops Drops fell between magnetic plates Drops radiated to give them negative charge Measured how fast they fell to find charge and mass Gravity pulls them down…But since opposite charges attract and likes repel The magnetic plates pushed the drops up

Millikan’s Calculations – Whoa!

What were Millikan’s conclusions? I have most accurately measured the charge of an electron: x Coulombs

What were Millikan’s conclusions? I have also most accurately measured the mass of an electron: x kg

What were Millikan’s conclusions? The electron is really really small and has a negative charge

Numero Seis! - Ernest Rutherford Experiment: Gold Foil Experiment When: 1910 Where: Montreal

Gold Foil Experiment Explained Alpha helium particles were shot through a piece of gold foil –Think aluminum foil but thinner and made out of gold! Alpha helium particles are 8000 times more massive (bigger) than electrons Rutherford thought alpha particles would knock electrons out of the way, since atom is only electrons in sea of positive charge

Remember! This is the current model of the atom (Thanks to Thomson)

More History Ernie’s (Rutherford) Big Adventure Thin Sheet of Gold Atoms

What were Rutherford’s conclusions? Pretend you are Rutherford As Rutherford, what conclusion would you make based on the data from the Gold Foil Experiment? = Hint: Positive repels positive, negative repels negative

What were Rutherford’s conclusions? Discovered the nucleus, a concentrated mass with positive protons! Nucleus is in the center of the atom The atom is mostly empty space Electrons orbit around nucleus

What’s this empty space idea? The atom is mostly empty space! The nucleus is TINY compared to the size of the entire atom! Called “the planetary model” because electrons orbit like planets in empty space

Relative Size of Nucleus to the Atom

Rutherford Simulation Let’s do this thing OURSELVES…but without radioactive particles

James Chadwick Experiment: Beryllium Foil Experiment When: 1932 Where: Cambridge (England)

Beryllium foil experiment Similar to gold foil experiment Shot alpha particles at beryllium foil Noticed neutral radiation coming out That neutral radiation could knock protons out of the way Therefore, heavy neutral particles exist in the atom

What were Chadwick’s conclusions? Neutral radiation emitted; therefore, the nucleus contains another subatomic particle called the neutron (has a neutral charge)

NUCLEUS NEUTRON ELECTRON PROTON

Picture History Draw a picture history of the atomic model on the timeline

RAFT - Independent Work Time Due Friday R = Role Pretend to be either Dalton, Thomson, Rutherford. A = Audience You are writing to the theorist directly before you. F = Format Newspaper article, Letter or Rap T = Topic Details of your discovery, how you know it is true, and why it is better than the guy before you. YOU HAVE “WORKED” HARD…DEFEND YOUR RESEARCH!

Assignment: RAFT Option 1: Rap Role: An atomic Theorist Audience: Writing to another atomic theorist Form: an appropriate rap Topic: Why your theory and model is better than theirs +3 points for presenting on Friday

Assignment: RAFT Option 2: Polite, Formal Letter or Newspaper article Role: An atomic Theorist Audience: Writing to another atomic theorist Form: a formal letter Topic: Politely stating why your theory and model proves theirs wrong +3 points for presenting on Friday

Assignment: RAFT Things to Include Personal information about both theorists - where they’re from, physical appearance, etc. All necessary facts about both theories or models How the theory is better than the one that came before it

3 Subatomic Particles Protons Neutrons Electrons

THE PROTON p+p+ Fat (heavy) Positive (charge) Doesn’t move (lazy)

THE NEUTRON N°N°  Fat (heavy) Neutral  (charge) Doesn’t move (lazy)

THE ELECTRON Skinny (very light) Negative  (charge) Moves a lot (runs around) e-e-

Review of Subatomic Particles Subatomic Particle LocationMassCharge Protons Neutrons Electrons NUCLEUS OUTSIDE NUCLEUS x kg x kg x kg 1+ NEUTRAL 1-

Review: Subatomic Particles e-e- N  P+P+

Exit Slip 1.What experiment did Rutherford use to? What did he discover? 2.How did Rutherford change the atomic model? Hw: Make it a QUALITY short answer –What are the three subatomic particles and how did we discover each? Name the experiment and give a brief description. Top ten: how’d we do?