Atoms are electrically
particles.
# of Protons = # of Electrons
For example a Magnesium atom (Mg) has 12 p+ and 12 e-. 12(+1) + 12(-1) = 0
are atoms that have become electrically
electrons.
# of Protons
by
or
the # of Electrons
For example, a Magnesium ion (Mg2+) loses 2 electrons so it has 12 p+ and 10 e-. 12(+1) + 10(-1) = +2
Why does this occur? Watch this: http://study.com/academy/lesson/ions-predicting-formation-charge-and-formulas-of-ions.html
 The
of an element depends on the
.
 The goal of every atom is to have a
valence (outermost) shell to be stable. This is called
the
.
 In order to obtain a full valence shell, atoms
with other atoms  forming
.
Atoms can do any of the following to obtain a full outer shell:
1.
(by giving an electron to another atom)
2.
(by taking electrons from another atom)
3.


Losing and gaining electrons will give the atom an
. Any element that
does NOT have the same number of protons and electrons is called an
. This means it has
an overall
.
But the ion is more stable than the original atom, because it has reached its goal of a full valence
shell.
Note: the electrons that are lost, shared, or gained are the ones furthest from the nucleus
the
.
Examples:
For each of the following questions,
(A) Draw a B-R diagram of the atom and ion
(B) Determine the number of valence electrons
Sodium
(C) Determine the net charge on the ion
Oxygen
The Lewis Structure of an Ion differs from the atom as follows:
 Electrons are either added or removed from the original Lewis structure of the atom
 Square brackets are drawn around the symbol and a superscript indicating the net charge of
the ION is written on the top right side of the bracket. For example, the oxygen ion is shown as:
Question: Draw the Lewis Structure for the (A) calcium atom/ion and the (B)fluorine atom/ion.
(A)
(B)
REACTIVITY OF METALS AND NON METALS:
 Metals with 1,2 or 3 valence electrons tend to
electrons producing
called
.
 Non Metals with 5, 6 or 7 valence electrons tend to
electrons producing
ions called
.
 Elements within the
on the periodic table form ions that all have
charge.
ions
Note: Hydrogen is special. It can gain or lose an electron to be stable. (Usually it loses an electron).
Consider the Following: Look at the BR worksheet that you filled out. What will the ionic charge be for the ions
formed from group 1? group 2? group15? group16? group 17? group18?
NAMING IONS:
 The name of a cation stays the
as the element name. Ex. sodium forms sodium ions.
 The name of an anion is different from the element name. The name of the anion is determine by
adding an “
” to the stem of the name.
Ex.
oxygen forms
fluorine forms
ELEMENT
GROUP
NUMBER OF VALENCE
ELECTRONS
TO OBTAIN A FULL SHELL
1
Alkali
Gain ____ electrons
Lose ____ electrons
2
Alkaline
13
Gain ____ electrons
Lose ____ electrons
Gain ____ electrons
Lose ____ electrons
Gain ____ electrons
Lose ____ electrons
Gain ____ electrons
Lose ____ electrons
Gain ____ electrons
Lose ____ electrons
14
15
16
17
halogens
Gain ____ electrons
Lose ____ electrons
18
Noble
Gain ____ electrons
Lose ____ electrons
CHARGE
Homework:
Read Page 188-190 and complete questions #1-9 on Page 190; Ion Worksheets; Study for quiz