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Slide 1 / 104 Slide 2 / 104 New Jersey Center for Teaching and Learning Progressive Science Initiative AP Chemistry This material is made freely available at www.njctl.org and is intended for the non-commercial use of students and teachers. These materials may not be used for any commercial purpose without the written permission of the owners. NJCTL maintains its Summer Assignment website for the convenience of teachers who wish to make their work available to other teachers, "The Basics" participate in a virtual professional learning community, and/or provide access to course materials to parents, students and others. Click to go to website: www.njctl.org www.njctl.org Slide 3 / 104 Slide 4 / 104 1 Which of the following were a part of Dalton's Atomic Dalton's Atomic Theory Theory? By the late 1800's, scientists worldwide had adopted John Dalton's Atomic Theory as the best explanation for the behavior of matter. A All matter is composed of atoms Matter is composed of atoms, B Atoms get rearranged in chemical reactions which are indivisible. Each compound consists of a set ratio of atoms. C Atoms of the same element are identical Atoms of same element are C C C C D A and B identical E A, B, and C Atoms of different elements are Si C different Atoms are not changed, created, Cl Cl H H or destroyed in a reaction, they H Cl are simply rearranged Cl H Slide 4 (Answer) / 104 Slide 5 / 104 1 Which of the following were a part of Dalton's Atomic 2 Which of the following components of Dalton's Theory? theory was proved incorrect by the discovery of isotopes? A All matter is composed of atoms A All matter is composed of atoms B Atoms get rearranged in chemical reactions B Atoms are rearranged in chemical reactions C Atoms of the same element are identical C Atoms of the same element are identical D A and B D Both A and B Answer E A, B, and C E E A, B, and C [This object is a pull tab]

Slide 5 (Answer) / 104 Slide 6 / 104 2 Which of the following components of Dalton's Protons, neutrons, and electrons theory was proved incorrect by the discovery of isotopes? A All matter is composed of atoms Atoms are composed of subatomic particles. B Atoms are rearranged in chemical reactions C Atoms of the same element are identical D Both A and B Protons and neutrons have similar masses (roughly 1 amu) Answer and together constitute the mass number (A) of an atom. C E A, B, and C # of protons + # of neutrons = mass number (A) [This object is a pull tab] Slide 7 / 104 Slide 8 / 104 Protons, neutrons, and electrons Protons, neutrons, and electrons Each element consists of atoms which differ in the number of protons compared to atoms of different elements. The atomic If an atom is electrically neutral, the number of electrons and number (Z) is equal to the number of protons in an atom. protons will be the same. # of protons = # of electrons # of protons = atomic number (Z) (neutral atom) Slide 9 / 104 Slide 10 / 104 Nuclide Symbols Nuclide Symbols & protons and neutrons There are two common ways the atomic mass and number are The number of protons and neutrons can be easily determined indicated for an atom. from the nuclear symbol. Method 1: Provides all information Example: How many protons and neutrons are present in the A < --- mass number 119 3 following? Symbol Cs or H 220 88 protons Z < --- atomic number 55 1 move for answer a) Ra 220 - 88 = 132 neutrons 88 Method 2: Must look up atomic number on the periodic table. Symbol - mass number Cs-199 or H-3 b) Au - 197 79 protons (from PT) atomic number 6 move for answer C 197 - 79 = 118 neutrons 12.01

Slide 11 / 104 Slide 11 (Answer) / 104 3 Barium is used to help take X-rays of the digestive 3 Barium is used to help take X-rays of the digestive system of the human body. What is the atomic system of the human body. What is the atomic number of barium (Ba)? number of barium (Ba)? A 38 A 38 B 48 B 48 C 137 C 137 D 4 D 4 E 56 E 56 Answer A [This object is a pull tab] Slide 12 / 104 Slide 12 (Answer) / 104 4 Which is the correct number of protons in an atom of 4 Which is the correct number of protons in an atom of vanadium (V)? vanadium (V)? A 23 A 23 B 51 B 51 C 18 C 18 D 24 D 24 E 50 E 50 Answer A Slide 13 / 104 Slide 13 (Answer) / 104 5 What is the mass of an element that has 10 protons 5 What is the mass of an element that has 10 protons and 11 neutrons? and 11 neutrons? Answer 21 [This object is a pull tab]

Slide 14 / 104 Slide 14 (Answer) / 104 6 How many neutrons are present in an oxygen 6 How many neutrons are present in an oxygen atom with a mass of 18 amu? atom with a mass of 18 amu? Answer 10 [This object is a pull tab] Slide 15 / 104 Slide 15 (Answer) / 104 7 What is the mass of an element with 18 protons, 18 7 What is the mass of an element with 18 protons, 18 electrons, and 22 neutrons? electrons, and 22 neutrons? Answer 40 [This object is a pull tab] Slide 16 / 104 Slide 16 (Answer) / 104 8 How many neutrons are present in atom with a mass of 8 How many neutrons are present in atom with a mass of 13 amu and an atomic number of 7? 13 amu and an atomic number of 7? Answer 6 [This object is a pull tab]

Slide 17 / 104 Slide 17 (Answer) / 104 9 How many neutrons are present in a neutral atom 9 How many neutrons are present in a neutral atom of Sr-80? of Sr-80? A 38 A 38 B 32 B 32 C 38 C 38 Answer D 80 D 80 E E 42 E 42 [This object is a pull tab] Slide 18 / 104 Slide 18 (Answer) / 104 10 How many electrons does this neutral element 10 How many electrons does this neutral element have? have? Na Na 23 23 11 11 Answer 11 Sodium Atom Sodium Atom [This object is a pull tab] Slide 19 / 104 Slide 19 (Answer) / 104 11 How many neutrons does this element have? 11 How many neutrons does this element have? Na Na 23 23 Answer 11 11 12 Sodium Atom Sodium Atom [This object is a pull tab]

Slide 20 / 104 Slide 20 (Answer) / 104 12 Which of the following has 45 neutrons? 12 Which of the following has 45 neutrons? A 80 Kr A 80 Kr B 80 Br B 80 Br C C 78 Se 78 Se D D 103 Rh 103 Rh Answer B [This object is a pull tab] Slide 21 / 104 Slide 22 / 104 Isotopes and a hole in Dalton's Theory Average Atomic Mass Dalton postulated that all atoms of a given element were identical. In the early 1900's scientists determined that certain atoms of lead When one examines even the smallest sample of an element, there were more stable than others - so there must be a difference! are hordes of atoms present. All of the stable isotopes of that element The difference was in the mass of the different atoms of lead. Since will be in the sample but not in the same abundance. the atoms were all lead they must have the same atomic number or number of protons. The difference in mass must be due to differing numbers of neutrons amongst the lead atoms!! For example, in a sample of carbon atoms, roughly 99% of the Atoms of the same element with differing numbers of neutrons atoms will be C-12 while 1% will be C-13. These percentages do are called isotopes! not vary no matter where, when, or how the sample was taken. Pb - 204 Pb - 206 82 protons 82 122 neutrons 124 Slide 23 / 104 Slide 24 / 104 Average Atomic Mass Calculating an Average Atomic Mass To find the average atomic mass of an element simply find the sum of the contribution of each isotope by multiplying the mass of each The mass listed on the isotope by it's abundance (expressed as a decimal instead of a %) 6 periodic table is a and adding them all together. C weighted average of the average atomic 12.01 isotopes of that particular mass element. Example: Neon consists of three stable isotopes: Ne-20, Ne-21, and Ne-22. If the relative abundance of these are 90.48%, 0.27%, and 9.25% respectively, what is the atomic mass of neon? *Note: The average atomic mass of carbon is much closer to 12 compared to 13. This is due to the much larger abundance of C-12. 20(.9048) + 21(0.0027) + 22(0.0925) = 20.18 amu