Transcript Chapter 12 The Periodic Table

IONS and E config
 Ions
are atoms that have lost or
gained electrons.
 Remember that the number of
protons cannot change for an
element.
 When an atom gains more electrons
than the number of protons it has it
will have a negative charge.
 When
an element loses more
electrons than the number of protons
it has, it will have a positive charge.
 What
drives atoms to give away
electrons or take on more?
Driving Force
 Full
Energy Levels are very low
energy
 Noble Gases have full orbitals
 Atoms behave in ways to achieve
noble gas configuration
Ionic Size
 Cations
are positive ions
 Cations form by losing electrons
 Cations are smaller than the atom
they come from
 Metals form cations
 Cations of representative elements
have noble gas configuration.
Ionic size
 Anions
are negative ions
 Anions form by gaining electrons
 Anions are bigger than the atom they
come from
 Nonmetals form anions
 Anions of representative elements
have noble gas configuration.
Configuration of Ions
Ions of representative elements
have noble gas configuration
 Na is 1s22s22p63s1
 Forms a 1+ ion - 1s22s22p6
 Same configuration as neon
 Metals form ions with the
configuration of the noble gas before
them - they lose electrons
Configuration of Ions
 Non-metals
form ions by gaining
electrons to achieve noble gas
configuration.
 They end up with the configuration of
the noble gas after them.
Group trends
 Adding
energy level
 Ions get bigger as
you go down
H1+
Li1+
Na1+
K1+
Rb1+
Cs1+
Periodic Trends
 Across
the period nuclear charge
increases so they get smaller.
 Energy level changes between
anions and cations
Li1+
B3+
Be2+
C4+
N3-
O2-
F1-
Keeping Track of Electrons
 The
electrons responsible for the
chemical properties of atoms are
those in the outer energy level.
 Valence electrons - The s and p
electrons in the outer energy level.
 Core electrons -those in the energy
levels below.
 Basis for shorthand
Keeping Track of Electrons
 Atoms
in the same column
 Have the same properties because
 Have the same outer electron
configuration.
 Have the same valence electrons.
 Found by looking up the group
number on the periodic table.
 Group 2A - Be, Mg, Ca, etc. 2 valence electrons
Lewis Dot diagrams help us
determine the charge
Electron Dot diagrams
A
way of keeping track of
valence electrons.
 How to write them
 Write the symbol.
 Put one dot for each
valence electron
 Don’t pair up until they
have to
X
The Electron Dot diagram
for Nitrogen
 Nitrogen has 5 valence
electrons.
 First we write the
symbol.
Then add 1 electron at a
time to each side.
Until they are forced to pair
up.
N
Write the electron dot diagram for
Na
F
Mg
Ne
C
He
O
Electron Configurations for
Cations
 Metals
lose electrons to attain noble
gas configuration.
 They make positive ions.
 Na 1s22s22p63s1 - 1 valence electron
 Na+ 1s22s22p6 -noble gas
configuration
Electron Dots For Cations
 Metals
will have few valence
electrons
Ca
Electron Dots For Cations
 Metals
will have few valence
electrons
 These will come off
Ca
Electron Dots For Cations
 Metals
will have few valence
electrons
 These will come off
 Forming positive ions
2+
Ca
Electron Configurations for
Anions
 Nonmetals
gain electrons to attain
noble gas configuration.
 They make negative ions.
 S 1s22s22p63s23p4 - 6 valence
electrons
 S2- 1s22s22p63s23p6 -noble gas
configuration.
Electron Dots For Anions
 Nonmetals
will have many valence
.electrons.
 They will gain electrons to fill outer
shell.
P
3P
Practice
 Use
electron dot diagrams to show
how the following form ions
 Al
 Cl
C
Stable Electron Configurations
All atoms react to achieve noble gas
configuration.
 Noble gases have 2 s and 6 p electrons.
 8 valence electrons .


Also called the octet rule.
Ar