Atomic Structure

Atoms An element is a species that is made of only 1 type of atom. Smallest particle of an element that has the properties of that element. Too small to be seen, even by strong microscopes.

Basic Building Blocks of Atoms Protons Positively charged particle located in the nucleus. Has a relative mass of 1 Neutrons Neutral particle located in the nucleus Electrons Negatively charged particle located outside the nucleus. Has a relative mass of 1/1836

Inside Atoms

C Periodic Table Cells 6 Carbon 12.011 Atomic Number Atomic Symbol Atomic Mass

Definitions Atomic Number Average Atomic Mass Atomic Mass Number Number of Protons in the nucleus. Essentially equivalent to the elements Social Security Number This number defines what the element is. No two elements have the same atomic number Average Atomic Mass Average mass of all the different types (Isotopes) of a single element The decimal number on the periodic table. Atomic Mass Number Sum of the number of protons and neutrons of a specific atom. Number cannot be a decimal number!!!!!

Isotopes Carbon has an weighted mass of 12.011. How is it possible to have .011 protons or neutrons….It isn’t Many elements have multiple different isotopes Isotopes are species of the SAME ELEMENT that have different numbers of neutrons

Isotopes Atoms with the same number of protons, but different numbers of neutrons. Atoms of the same element (same atomic number) with different mass numbers Isotopes of chlorine 35Cl 37Cl 17 17 chlorine - 35 chlorine - 37

How to figure out how many P+, No, and e- are in an atom Atomic # = the number of protons Atomic Mass # = protons + neutrons For any atom, the atomic # also tells how many electrons there are.

Ex: How many protons, neutrons and electrons are in U-236. On the Periodic Table, Uranium has an atomic number of 92. The -236 Tells us how much that specific uranium species weighs. P+ = atomic number = 92 No = Mass # - atomic # = 236-92 = 144 E- = atomic number = 92

Example Problem How many proton are in the following atom? Atomic Mass Number = 64 Number of Neutrons = 35 Number of Protons = ???

Example Problem Solved How many proton are in the following atom? Atomic Mass Number = 64 Number of Neutrons = 35 Number of Protons = ??? Protons + Neutrons = Mass Number (X) + 35 = 64 64-35 = X X= 29

Isotopes Atoms with the same number of protons, but different numbers of neutrons. Atoms of the same element (same atomic number) with different mass numbers Isotopes of chlorine 35Cl 37Cl 17 17 chlorine - 35 chlorine - 37

Ions An ion is an atom that has lost or gained one or more electrons. To determine the number of electrons, you must know the ion’s charge. For every (+) , you subtract an electron For every (-) , you add an electron. Charge = #P+ - #e-

Example Oxygen most often has a charge of (-2) when it becomes an ion. How many electrons does an oxygen ion have? Charge = (-2), so…. -2 = 6 -X -2 - (6) = -X -8 = -X 8 = X

Fill out this Chart Element Atomic # Mass # Charge # Protons # Neutrons # Electrons Phosphorous 15 16 Zinc 66 Sodium 22 +1 Plutonium 94 244

Fill out this Chart Element Atomic # Mass # Charge # Protons # Neutrons # Electrons Phosphorous 15 31 16 Zinc 30 66 36 Sodium 11 23 +1 12 10 Plutonium 94 244 150