Presentation on theme: " Protons, neutrons, electrons too Make up the atoms all around you!"— Presentation transcript:
Protons, neutrons, electrons too Make up the atoms all around you!
Nucleon – general term for nuclear particles. What are nuclear particles? Protons – positively charged particles in the nucleus of an atom that identifies the element: atomic number on the periodic table: has a mass of ~1 amu Neutrons – neutral particles in the nucleus of an atom: number may vary: has a mass of~ 1 amu
Electrons – negatively charged particles found in orbitals outside the nucleus (electron cloud): determines the reactivity of the atom: have virtually no mass ( 1/1840 amu) Sum of protons and neutrons gives the mass number (weight) of the atom amu is based on 1/12 of the carbon-12 atom – a reference isotope
What’s an isotope? Atoms of the same element having different numbers of neutrons (therefore different masses) are called isotopes. They have the same number of protons (identity stays the same).
Ex. Hydrogen has 3 isotopes hydrogen – 1, hydrogen – 2, and hydrogen -3 May be represented several ways. H-1, hydrogen-1, 1 H 1, 1 H, (nuclide) Mass number as a superscript and atomic number as a subscript. May see both on the left side of element symbol. Which do you think is the most abundant isotope? (hint: look at the periodic table)
Mass number on the periodic table is actually the average atomic mass – a weighted average based on the percent abundance of the naturally occurring isotopes. That’s why they almost always have decimals! A mass number is usually a whole number, sum of protons and neutrons – can’t have just a piece of a neutron or proton in an atom.
Copper exists as a mixture of two isotopes. Cu-63 makes up 69.17% of copper atoms and Cu-65 makes up 30.83% of copper atoms. If the atomic mass of Cu-63 is 62.930 amu and the atomic mass of Cu-65 is 64.928 amu, calculate the average atomic mass of copper based on the percent abundance of the two isotopes.