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Catalyst 11/2/10 No New Objective Please have out chart to be checked 1. Which of the following statements best explains the results of Trials 1–3 ? A. The light was too intense to eject electrons from the metal in the photocell.
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Catalyst 11/2/10 No New Objective Please have out chart to be checked 1. Which of the following statements best explains the results of Trials 1–3 ? A. The light was too intense to eject electrons from the metal in the photocell. B. The light was too intense to eject photons from the metal in the photocell. C.Theenergy per electron was too high to eject photons from the metal in the photocell. D. The energy per photon was too low to eject electrons from the metal in the photocell. 2. When 8.0 eV photons were shone on the photocell, electrons ejected from the metal in the photocell had a maximum kinetic energy of 4.9 eV. Based on this information and Table 1, the relative intensity of the light shone on the photocell: A.was high. B.was medium. C.was low. D.cannotbe determined.
Agenda • Subatomic Particle Review (15-30) • Ion and Isotope Notes/Practice (30) • Homework: • 1, 2, 5 & 7: • Pick 10 additional elements to add to chart • 4 & 5 • atoms, ions, and isotopes worksheet
Atomic Mass Symbol Atomic Number
Hydrogen Protons: 1 Neutrons: 0 Electrons: 1 H 1 1
Sodium Protons: 11 Neutrons: 12 Electrons: 11 Na 23 11
Rhenium Protons: 75 Neutrons: 111 Electrons: 75 Re 186 75
Try these: Name/ Atomic # Mass P N E Symbol Niobium In Arsenic Lead Au Zr V Iron Ni W
ION Atoms of the same element that differ in charge.(They have the same # of p+, but different # of e-)
Ex: How many electrons does Sodium have? The atomic number equals the number of protons and the number of electrons. 22.99 11 electrons Na 11
Negative Ions(anions) Positive Ions(cations) • Na+ (lost 1 e-) • Ca2+ (lost 2 e-) • Al3+ (lost 3 e-) • Pb4+ (lost 4 e-) • H+ (lost 1 e-) • Cl- (gain 1 e-) • O2- (gain 2 e-) • P3- (gain 3 e-) • S2- (gain 2 e-) • OH- (gain 1 e-)
If an atom GAINS electrons, its overall charge becomes more negative.If it LOSES electrons, its charge becomes more positive
Learning Check – Counting State the number of protons, neutrons, and electrons in each of these ions. 39 K+16O -241Ca +2 19 8 20 #p+ ______ ______ _______ #no ______ ______ _______ #e- ______ ______ _______
ISOTOPE Atoms of the same element that differ in mass.(They have the same # of p+, but different # of N°)
Isotopes are CHEMICALLY the SAME as atoms, but DIFFER PHYSICALLY because they have different masses.
Learning Check – Counting Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of these carbon atoms. 12C 13C 14C 6 6 6 #p+ _______ _______ _______ #no _______ _______ _______ #e- _______ _______ _______
Answers 12C 13C 14C 6 6 6 #p+666 #no678 #e- 6 66
One Last Learning Check Write the nuclear symbol form for the following atoms or ions: A. 8 p+, 8 n, 8 e- ___________ B. 17p+, 20n, 17e- ___________ C. 47p+, 60 n, 46 e- ___________
So, why do the elements on the PT have masses with decimals???
The periodic table has the average atomic mass of all of the isotopes of a substance
11B 10B AVERAGE ATOMIC MASS • Because of the existence of isotopes, the mass of a collection of atoms has an average value. • Boron is 20% 10B and 80% 11B. That is, 11B is 80 percent abundant on earth. • For boron atomic weight = 0.20 (10 amu) + 0.80 (11 amu) = 10.8 amu
Average atomic mass is calculated by: • Mass each isotope and multiply by amount • Add calculations for each isotope • Divide sum by the total amount