Presentation on theme: "Isotopes Atoms of the same element that different mass numbers"— Presentation transcript:
1 Isotopes Atoms of the same element that different mass numbers (which means they have different numbers of neutrons)They can be written two ways:element name - mass numberSymbolmass #atomic #carbon - 126 p+ and 6 n0C126C136carbon - 136 p+ and 7 n0C146carbon - 146 p+ and 8 n0Remember:mass number = p+ + n0X3517(a)X3518(b)X3717(c)X3819(d)Which of the following areisotopes of the same element?
2 Atomic Mass x 75.77% = x 24.23% = 896.51 + = = 35 amu 2651.95 37 amu A weighted average of the masses of all the isotopes of an element.Step 1: Multiply the mass by its percent for each isotopeStep 2: Add them togetherStep 3: Divide by 100Use "amu" for its unit of measureExample: Chlorine has two naturally occurring isotopes, chlorine-35 and chlorine-37. Their relative abundances are 75.77% and 24.23%, respectively. Calculate the atomic mass for chlorine.35 amux75.77%=37 amux24.23%=896.51+==35.5 amu100
3 Atomic Mass x 19.91% = x 80.09% = + = = 10.012 amu 199.34 11.009 amu Example: Element X has two natural isotopes. The isotope with a mass of amu has a relative abundance of 19.91%. The isotope with a mass of amu has a relative abundance of 80.09%. Calculate the atomic mass of this element.amux19.91%=199.34amux80.09%=881.71+==10.8 amu100