Periodic table & more How it’s arranged and how do electrons fill an atom….

 The periodic table is divided into periods and groups.  Each horizontal row is called a period.  Each vertical column is called a group.

Groups

 All the elements in Group 1 of the periodic table form similar compounds.  Atoms within a group have similar properties.

The mass of individual atoms is so small that the numbers are difficult to work with.  To make calculations easier, scientists use the atomic mass unit (amu).  The atomic mass of any element is the average mass (in amu) of an atom of each element.

Each energy level corresponds to a period of the periodic table! KEY POINT!

Energy levels for the first 3 periods:

Now let’s talk about electron configurations….  Energy levels come in many types. The main ones are called: s, p, d, & f Each type holds a specific amount of electrons.

Electrons for each orbital type: S = 2 P = 6 D = 10 F = 14

1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 4f 14 5d 10 6s 2 6p 6 5f 14 6d 10 7s 2 7p 6 This is the E- config. for Ununoctium: : This is how the electrons fill orbitals around the nucleus of the atom.

 The main thing you need to know is that it’s the valence electrons or outer orbital electrons that matter most!  We can tell how many outer electrons or valence electrons there are by looking at the periodic table!

Let’s Practice!  Let’s Try Argon, or Ar, # 18 on the periodic table.  Ar has ___ protons, therefore it has ____ electrons.  How do we write it’s electron configuration?  We follow the order first: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 4f 14 5d 10 6s 2 6p 6 5f 14 6d 10 7s 2 7p 6 (Remember this from ununoctotium & use it for all your problems!)  Ar: 1s2 2s2 2p6 3s2 3p6 = 18

Let’s try another!  Let’s Try Chlorine, or Cl, # 17 on the periodic table.  Cl has ___ protons, therefore it has ____ electrons.  Cl: 1s2 2s2 2p6 3s2 3p5 = 17  Cl looks like this: Lewis diagram

One last one!  Let’s Try Sodium, or Na, # 11 on the periodic table.  Na has ___ protons, therefore it has ____ electrons.  Na: 1s2 2s2 2p6 3s1 = 11  Na looks like this: Lewis diagram