1 / 16

Isotopes

Mass #. Atomic #. Isotopes. Atoms of the same element with different mass numbers. Nuclear symbol:. Hyphen notation: carbon-12. Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem. Neutron. Nucleus. Proton. Proton. +. Nucleus. +. Neutron. +. +. +. Carbon-12.

adrian-woods
Download Presentation

Isotopes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Mass # Atomic # Isotopes • Atoms of the same element with different mass numbers. • Nuclear symbol: • Hyphen notation: carbon-12 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  2. Neutron Nucleus Proton Proton + Nucleus + Neutron + + + Carbon-12 + + + + + + + Carbon-14 Isotopes Electrons Nucleus Electrons Neutrons 6 Protons 6 Electrons 6 Neutrons 8 Protons 6 Electrons 6 Nucleus

  3. 17 Cl 37 Isotopes • Chlorine-37 • atomic #: • mass #: • # of protons: • # of electrons: • # of neutrons: 17 37 17 17 20 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  4. Avg. Atomic Mass Average Atomic Mass • weighted average of all isotopes • on the Periodic Table • round to 2 decimal places Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  5. Avg. Atomic Mass Average Atomic Mass • EX: Calculate the avg. atomic mass of oxygen if its abundance in nature is 99.76% 16O, 0.04% 17O, and 0.20% 18O. 16.00 amu Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  6. Avg. Atomic Mass Average Atomic Mass • EX: Find chlorine’s average atomic mass if approximately 8 of every 10 atoms are chlorine-35 and 2 are chlorine-37. 35.40 amu Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  7. Isotopes Dalton was wrong. Atoms of the same element can have different numbers of neutrons different mass numbers called isotopes C-12 vs. C-14 California WEB

  8. Naming Isotopes • Put the mass number after the name of the element • carbon- 12 • carbon -14 • uranium-235 California WEB

  9. Atomic Mass • How heavy is an atom of oxygen? • There are different kinds of oxygen atoms. • More concerned with average atomic mass. • Based on abundance of each element in nature. • Don’t use grams because the numbers would be too small California WEB

  10. Measuring Atomic Mass • Unit is the Atomic Mass Unit (amu) • One twelfth the mass of a carbon-12 atom. • Each isotope has its own atomic mass we need the average from percent abundance. California WEB

  11. Calculating averages • You have five rocks, four with a mass of 50 g, and one with a mass of 60 g. What is the average mass of the rocks? • Total mass = (4 x 50) + (1 x 60) = 260 g • Average mass = (4 x 50) + (1 x 60) = 260 g 5 5 • Average mass = 4 x 50 + 1 x 60 = 260 g 5 5 5 California WEB

  12. Calculating averages • Average mass = 4 x 50 + 1 x 60 = 260 g 5 5 5 • Average mass = .8 x 50 + .2 x 60 • 80% of the rocks were 50 grams • 20% of the rocks were 60 grams • Average = % as decimal x mass + % as decimal x mass + % as decimal x mass + California WEB

  13. Isotopes • Because of the existence of isotopes, the mass of a collection of atoms has an average value. • Average mass = ATOMIC WEIGHT • Boron is 20% B-10 and 80% B-11. That is, B-11 is 80 percent abundant on earth. • For boron atomic weight = 0.20 (10 amu) + 0.80 (11 amu) = 10.8 amu

  14. Atomic Mass Magnesium has three isotopes. 78.99% magnesium 24 with a mass of 23.9850 amu, 10.00% magnesium 25 with a mass of 24.9858 amu, and the rest magnesium 26 with a mass of 25.9826 amu. What is the atomic mass of magnesium? If not told otherwise, the mass of the isotope is the mass number in amu. 24.304 amu California WEB

  15. 29 Cu 63.548 Atomic Mass Calculate the atomic mass of copper if copper has two isotopes. 69.1% has a mass of 62.93 amu and the rest has a mass of 64.93 amu.

  16. Given the average atomic mass of an element is 118.21 amu and it has three isotopes (“A”, “B”, and “C”): isotope “A” has a mass of 117.93 amu and is 87.14% abundant isotope “B” has a mass of 120.12 amu and is 12.36% abundant Find the mass of isotope “C”. Show work for credit.

More Related