1. Chapter 3 – Atoms and the Periodic Table ParticleChargeMassLocation Proton+1 1 amu In Nucleus Neutron0 1 amu In Nucleus In Nucleus Electron 0 amu Outside Nucleus The Structure of an Atom amu = Atomic Mass Unit

2. Chapter 3 – Atoms and the Periodic Table  An atom is mostly space with a very small nucleus and an electron “cloud”  The number of protons is the atomic number on the periodic chart  Example: C has 6 protons N has 7 protons N has 7 protons Au has 79 protons Au has 79 protons

3. Chapter 3 – Atoms and the Periodic Table Mass #

4.  Mass Number – is the mass of an atom  Atom’s mass = protons + neutrons  # neutrons = mass # - protons  Isotopes – atoms of the same element that have a different number of neutrons.

5. Isotopic Notation

6. Draw a diagram of each of the following isotopes H-3H-2H-1 H-3H-2H-1 Na-22Na-24Na-23 1.What is the charge on the nucleus of a Na atom? 2.What is the charge on the electron cloud of a Na atom? 3.What is the overall charge on the Na atom? +11 -11 0

7.  An atom that has gained or lost electrons is called an ion. A Na atom becomes an ion by the loss of one electron. What will be the charge on the sodium ion? Sodium ion 11 protons +11 10 electrons -10 +1 net charge

8. Determine the charge on each of the following ions 8p +8 5p +59p +9 10e -10 2e -210e -10 -2 charge +3 charge -1 charge -2 charge +3 charge -1 charge

9.  Valence electrons – outer electrons that are involved in chemical reaction (will be from 1 to 8 electrons).  All chemical reactions are competition for these outer electrons  We show these outer electrons by electron dot diagrams. LiBeBFNe NaSrGaIKr

10.  1869 Dimitri Mendeleev arranged the elements by increasing mass and by chemical properties.  This was the first periodic table of the elements. I developed the 1 st periodic table

11. Family Groups  Nobel Gases (inert gases)  Have 8 outer electrons. This fills their outer orbitals and is very stable.  Nobel gases do not undergo chemical reactions  Fluorine Family (the halogens)  Have 7 outer electrons  Need one more electron to fill outer shell  They react to take one electron from another element

12.  Oxygen Family  Have 6 outer electrons  They need two more electrons  They react to take two more electrons from another element  Alkali Metals (the Li family)  They have one outer electron  They always react to lose this electron  Alkaline Earth Metals (the Be family)  These have two outer electrons  They always react to lose these two electrons

13. Elements can also be classified as metals, nonmetals, and metalloids  Metalloids  B, Si, Ge, As, Sb, Te, and At  Mark these on your chart!  These elements form a diagonal line  Elements to the upper right of this line are the nonmetals  Elements to the lower left on this line are the metals  Have properties in between metals & nonmetals  Semiconductors (conduct electricity poorly)

14.  Metals  Shiny  Conduct electricity  Are malleable (can be shaped by hammering)  React with nonmetals to lose electrons  Nonmetals  Not shiny  Do not conduct electricity  Not malleable  React with metals to gain electrons  React with other nonmetals to share electrons