Atomic Structure Notes PDF

1. Atomic Structure Review How can we discuss atoms without having to draw them?  2 What’s in an atom? ⊗ Atoms are made of THREE subatomic particles: protons neutrons electrons ⊗ Each...

1. Atomic Structure Review How can we discuss atoms without having to draw them?  2 What’s in an atom? ⊗ Atoms are made of THREE subatomic particles: protons neutrons electrons ⊗ Each WHOLE atom can be identified by its unique number of protons meaning each atom with a different number of protons is a new element and can be found on the periodic table of the elements +  3 ⊗ Atomic mass is measured in + atomic mass units ⊚ One amu = the weight of ONE proton or ONE neutron ⊗ An atom’s electrons are so tiny that the mass of them isn’t enough to affect the overall mass of the atom (we call this negligible mass).  4 Parts of an atom: + Abbreviation Charge Location Relative Mass Protons p+ or + + nucleus 1 amu Neutrons n0 or n 0 nucleus 1 amu Electrons - Electron e or - - Cloud negligible  5 Using the Periodic Table We will use the periodic table to find atomic numbers, names, and symbols of elements. Using the Periodic 6 Table ATOMIC NUMBER = number of protons ⊗ Can be found on the periodic table ⊗ This is the amount of protons in the nucleus and identifies what element the atom is ⊗ This is the ONLY characteristic that is guaranteed to be the same for atoms of the same element Using the Periodic 7 Table MASS NUMBER = Number of protons + neutrons ⊗ Must be given. NOT on the periodic table! ⊗ Elements can be written with their mass or mass/neutron number is provided ⊚ Example: Uranium-235, carbon with 8 neutrons ⊗ This is how much the nucleus weighs in amu’s Using the Periodic 8 Table NUMBER OF NEUTRONS = Mass number - atomic number ⊗ Must be given. NOT on the periodic table! ⊗ Number of neutrons can CHANGE atom to atom ⊗ An atom with a different number of neutrons is called an isotope Using the Periodic 9 Table NUMBER OF ELECTRONS = atomic number IF an atom is neutral! ⊗ Can be found on the periodic table (if neutral) ⊗ Atoms that are NOT neutral are called ions ⊗ Ion charges are indicated by superscripts like this Using the Periodic Table Practice 1. Using your periodic table, which element has 32 protons in its nucleus? a. Sulfur b. Germanium c. cesium 2. Using your periodic table, what is the chemical symbol for the NEUTRAL element that contains 9 electrons? a. Be b. Fl c. Ar d. F 3. An atom has 3 protons, 3 electrons, and 3 neutrons - what is its atomic mass? a. 3 amu b. 6 amu c. 9 amu d. 12 amu  2. Isotopes What CAN change in the nucleus? Isotopes are atoms of the same element with different amounts of 12 neutrons For example, we could have 25 Mg magnesium with a mass of 24 amu OR a mass of 25 amu. Mg will always have an atomic 12 number of 12 but the number of neutrons can change. Magnesium-25  13 Isotope Name and Notation Mass # = p+ + n0 25 Mg Isotope Symbol Atomic # = p+ 12 Isotope Name = Magnesium-25 Element Name-Mass# 14  15 For example, there are three types of Hydrogen: Name p+ n0 Mass# Diagram Isotope Symbol e- p+ 1 1H Hydrogen-1 1 0 1 e- n0 2 1H + Hydrogen-2 1 1 2 p e- 3 1H n0 Hydrogen-3 1 2 3 p+ n0 Isotopes Practice 1. Use your periodic table - how many PROTONS are in an atom of beryllium-10? ___ 2. Use your periodic table - how many NEUTRONS are in an atom of beryllium-10? ___ 3. What is the correct isotope symbol for an atom of fluorine-18 in the image 4. Draw the below protons, neutrons, and electrons for an atom of fluorine-18