Presentation on theme: "Essential Question: How do atoms of the same element differ?"— Presentation transcript:
1 Essential Question: How do atoms of the same element differ? IsotopesEssential Question: How do atoms of the same element differ?
2 What is an Isotope?Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons.All elements consist of naturally occurring isotopes and artificially produced isotopes
3 How are isotopes of an element similar? How are they different? The isotopes of an element have:Identical Chemical Properties (this is because they have the same numbers of protons and electrons and subatomic particles are responsible for chemical behavior)Different Physical Properties (different mass and different number of neutrons)
4 How do we represent specific isotopes? Nuclear symbols are used to represent specific isotopesTo write a nuclear symbol:1.) the symbol of the element is written first2.) the mass number is written as asuperscript to the left of the symbol3.) the atomic number is written as asubscript to the left. Study the illustration belowLi-7 isotope
5 Learning CheckGiven a nuclear symbol, what does the top left number represent?What does the bottom left number represent?
6 Can we write isotopes in a different way? You can also use the mass number and the name of the element to designate the atom or isotopeThis is called hyphen notationFor example, two isotopes of carbon are carbon-12 and carbon-13The nuclear symbols for these two isotopes would be:C126136C
7 Learning CheckWhat does the number after the hyphen represent?
8 What do the numbers used when writing isotopes represent? The mass numbertotal number of protons and neutrons in a specific nucleus of an atom.The atomic numberalways refers to the total number of protons in an atom.
9 How do I figure out the number of neutrons when writing isotopes? To determine the number of neutrons in a specific isotopesubtract the atomic number from the mass numberSee the formula belowMass Number (neutrons + protons)Atomic Number (number of protons)(number of neutrons)
10 Learning Check Boron consists of two isotopes, B-10 and B-11 1.) Determine the number of neutrons in each of theisotopes2.) Using the periodic table, write the nuclear symbolfor each isotope given in hyphen notationa.) B-10: – 5 = 5 neutronsb.) B-11: – 5 = 6 neutrons
11 What does the atomic weight of an element depend on? To identify isotopes the mass number is placed after the element’s nameEx: chlorine-35 potassium-37The atomic weight of an element depends on the abundance of its isotopes.If you know the mass of the isotopes and the percent (fractional) abundance of the isotopes, you can calculate the element's atomic weight.
12 How do I calculate the atomic mass of an element based on percent natural abundance and isotopic masses?Example: Chlorine has 2 naturally occurring isotopesTo calculate the average atomic weight:add the mass of each isotope multiplied by its percent abundanceThis is the solution for chlorine:( ) * (0.7577) + ( ) * (0.2423) = amuMass #MassPercent Abundance3575.773724.23
13 Learning Check Nuclear Symbol Complete based on the following information:29 protons, mass 65Barium - 13817 protons, mass 36Tin - 12016 protons, mass 30