On the front page of the Packet! Launch Get Out Your Unit 2 Packet, calculator, and a pen/pencil Grade yourself on ALT 2 Open to the Unit 2 Study Guide Write One thing you still don’t get. Two things you totally “get.” Be prepared to ask about what you don’t get as we go through the guide 11/12 (Th) On the front page of the Packet!

Unit 2: Atoms and Radioactivity Learning Target: I can use models to describe how changes in the internal structure of the atom (protons, neutrons, and electrons) & determine the properties and identity of the atom.

Teacher Directed Review of Guide Purpose: Answer student questions PLEASE: No side-conversations Raise your hand to join in Correct your answers as we go There will not be time to copy these answers into a blank study guide.

ATOMS Essential Question How are the smallest bits of matter described? ATOMS

Evidence Supporting Model Scientist Evidence Supporting Model John Dalton He mixed elements in chemical reactions. He saw that they always combined in whole number ratios: Like 1:2 or 3:2  JJ Thomson He zapped atoms with electricity and saw that negatively charge particles were ejected. Ernest Rutherford  He shot alpha particles at gold foil and saw that a few bounced back instead of going through. He hypothesized there must be a small, dense area inside the atom.  Neils Bohr He devised a model with electrons in orbits that explained the different flame colors of the elements.

The subatomic particles of atoms Particle Name Symbol Charge Location Mass (amu) Proton p+ +1 Nucleus 1 amu Electron e- -1 Around the nucleus Basically 0 Neutron n0

When are atoms electrically neutral? Protons + 1 charge Electrons -1 charge When protons = electrons

Atoms by the Numbers 9 F 19.00 10 19 26 Fe 55.85 30 56 3 Li 9.012 4 7 Atomic # Symbol of element Avg. atomic mass (amu) Number of protons Number of neutrons Atomic** Mass (amu) Number of electrons 9 F 19.00 10 19 26 Fe 55.85 30 56 3 Li 9.012 4 7 K 39.10 41-22=19 22 41 ** Do NOT use the periodic table to calculate this! #p + #n0

ISOTOPES Essential Question How can atoms of the same element be different? ISOTOPES

Isotopes Beryllium-5 4 1 5 Potassium-40 19 21 40 Potassium-39 20 39 Isotope Name Atomic number # of protons # of neutrons Atomic Mass (amu) # of electrons Isotope Symbol Beryllium-5 4 1 5 Potassium-40 19 21 40 Potassium-39 20 39 Lithium-6 3 6 Lithium-7 7

Compare/Contrast Isotopes of an element Li-6 Li-7 n0 = 4 Mass is 7 amu Symbol has a 7 in upper left n0 = 3 Mass is 6 amu Symbol has a 6 in upper left atomic # is 3 Symbol is Li p+ is 3 e- is 3

Simple Atomic Model Be

The average atomic mass of copper is 63. 55 amu The average atomic mass of copper is 63.55 amu. This tells me that most of the atoms must be copper-63 since 63 amu is closer to the average than 65 amu for copper-65. Cu-63 Cu-65 63.55 amu

Calculate average atomic mass Isotope Mass (amu) Abundance (%)   28 92 29 5 30 3 Si-28 X = 92 100 = 25.76 amu = 5 100 Si-29 X = 1.45 amu = 3 100 Si-30 X = 0.9 amu 28.11 amu 1. Convert each abundance to a decimal 2. Multiply each mass by its abundance 3. Add these up to get the average atomic mass

RADIOACTIVE DECAY Essential Question How can we change an element’s identity? RADIOACTIVE DECAY

Best shielding (what blocks it) Types of Radiation Radiation Symbol Charge Mass (amu) Best shielding (what blocks it)   Alpha +2 4 Paper Beta -1 Aluminum foil Gamma γ Lead or thick concrete

Nuclear Equations

Chemistry Test Day Selfie Then OFF AND AWAY All Period

Assessment Testing Procedures Did you FINISH the test or quiz? You may not leave the room for any reason once you start the Exam. NO EXCEPTIONS. Ground Rules Keep eyes on own papers. Work silently. No cell phones, iPods, etc. AHS Integrity policy is in effect. Assessment Did you FINISH the test or quiz? Flip it over, take out a book, or other silent activity. remain seated