Here we’ll look at how nonmetal atoms form ions.
npp pn
n n pn
p
p pn n
nnp n p
The nucleus of a
fluorine atom
12 protons
12 neutrons
The nucleus we’ve shown here is the nucleus of a fluorine atom. The box for
fluorine on the periodic table is shown on the left side of the video here.
npp pn
n n pn
p
p pn n
nnp n p
Fluorine has an atomic number of 9
The nucleus of a
fluorine atom
9 protons
10 neutrons
npp pn
n n pn
p
p pn n
nnp n p
The nucleus of a
fluorine atom
9 protons
10 neutrons
Which means, the nucleus of a fluorine atom has 9 protons.
npp pn
n n pn
p
p pn n
nnp n p
The nucleus of a
fluorine atom
9 protons
10 neutrons
Almost all fluorine atoms has 10 neutrons in their nucleus. The number of neutrons does
not change when an atom becomes and ion, and neutrons have no effect on charge.
npp pn
n n pn
p
p pn n
nnp n p
Because protons all have a positive 1 charge,
Protons all
have a +1
charge
n++ +n
n n +n
+
+ +n n
nn+ n +
We’ll replace all the p’s with positive charges
n++ +n
n n +n
+
+ +n n
nn+ n +
The nucleus of
a fluorine
atom has a
total charge of
+9
So the nucleus of a fluorine atom has 9 positively charged protons
n++ +n
n n +n
+
+ +n n
nn+ n +
+9
Therefore, it has a total charge of positive 9
The nucleus of
a fluorine
atom has a
total charge of
+9
n++ +n
n n +n
+
+ +n n
nn+ n +
+9
The nucleus of
a fluorine
atom has a
total charge of
+9
A neutral atom of fluorine
has 9 electrons
Electrons have a negative charge. So a neutral atom of fluorine (click) must have 9
electrons to balance the positive 9 charge on the nucleus
A neutral atom
of fluorine has
9 electrons
electrons in shells
2, 8, 2
Here, we’ll use the Bohr Model of the atom, (click) where the electrons occupy
shells around the nucleus.
electrons in shells
2, 7
–
–
A neutral atom
of fluorine has
9 electrons
The first shell has two electrons, the maximum number it can hold.
electrons in shells
–
2, 7
–
–
–
–
–
–
A neutral atom
of fluorine has
9 electrons
–
–
A fluorine atom has a total of 9 electrons, so the second shell has a total of 7
electrons.
–
–
–
–
9p
10 n
–
–
–
A neutral atom
of fluorine has
9 electrons
–
–
The nucleus has 9 protons and 10 neutrons. Instead of a picture, this is usually
simplified by showing a circle (click) with 9 p and 10 n
–
–
–
–
9p
10 n
–
–
–
a fluorine
atom
–
–
So this is how we represent a neutral fluorine atom
–
–
–
–
9p
10 n
–
The second
shell is not
filled, so
this atom is
unstable
–
–
a fluorine
atom
–
–
We see that in a fluorine atom, the second shell (click) only has 7 electrons, and it
can hold 8, so (click) the second shell is not filled
–
–
–
–
9p
10 n
–
–
–
a fluorine
atom
Therefore, this atom is unstable
–
–
The second
shell is not
filled, so
this atom is
unstable
–
–
–
In order to
become
stable, this
atom must
gain 1
electron
–
9p
10 n
–
–
–
–
–
a fluorine
atom
In order to fill up the second shell and become stable, a fluorine atom (click) must
gain one electron
–
–
–
–
In order to
become
stable, this
atom must
gain 1
electron
Right here
–
9p
10 n
–
–
–
–
–
a fluorine
atom
–
–
–
–
–
9p
10 n
–
–
–
–
–
a fluoride
fluorine
ion
atom
This now has 9 protons and 10 electrons, so it can no longer be called a fluorine
atom. It is (click) now called a fluoride ion.
–
–
–
–
–
9p
10 n
–
–
–
–
Notice, the name of this ion ends in “ide”
–
a fluoride
ion
–
Names of
negative ions
of nonmetals
end in “ide”
–
–
–
–
9p
10 n
–
–
–
–
–
a fluoride
ion
Names of negative ions of non-metals are always changed so they end in “ide”
(click)
–
This ion is
stable. It has
the same
electron
arrangement
as the noble
gas neon:
completely
filled first and
second shells
This ion is stable,
–
–
–
–
9p
10 n
–
–
–
–
–
a fluoride
ion
–
This ion is
stable. It has
the same
electron
arrangement
as the noble
gas neon:
completely
filled first and
second shells
–
–
–
–
9p
10 n
–
–
–
–
–
a fluoride
ion
(start new sentence) Because it has 10 electrons, it has the same electron
arrangement as the noble gas neon
–
This ion is
stable. It has
the same
electron
arrangement
as the noble
gas neon:
completely
filled first and
second shells
–
–
–
9p
10 n
–
With completely filled first
–
–
–
–
–
a fluoride
ion
–
This ion is
stable. It has
the same
electron
arrangement
as the noble
gas neon:
completely
filled first and
second shells
And second shells
–
–
–
–
9p
10 n
–
–
–
–
–
a fluoride
ion
9 protons (+)
–
–
–
–
–
9p
10 n
–
–
–
a fluoride
ion
–
A fluoride ion has a total of 9 protons
–
–
9 protons (+)
10 electrons (–)
–
–
–
–
9p
10 n
–
–
–
a fluoride
ion
And 2 plus eight or 10 electrons
–
–
–
9 protons (+)
10 electrons (–)
–
+++++++++
–
–
–
9p
10 n
–
–
–
a fluoride
ion
–
9 protons means it has 9 positive charges
–
–
9 protons (+)
10 electrons (–)
–
–
–
–
9p
10 n
–
–
–
a fluoride
ion
–
–
And 10 electrons means it has 10 negative charges
+++++++++
––––––––––
–
9 protons (+)
10 electrons (–)
–
–
–
–
9p
10 n
–
+++++++++
––––––––––
–
–
a fluoride
ion
–
–
Positive and negative charges neutralize each other, amd what is left over is called
the..
–
–
+++++++++
––––––––––
– Net charge: –
Net charge: –1
–
Net charge: –
–
–
9p
10 n
–
–
a fluoride
ion
Net charge
–
9 protons (+)
10 electrons (–)
–
–
–
+++++++++
––––––––––
– Net charge: –
Net charge: –1
–
Net charge: –
–
–
9p
10 n
–
–
a fluoride
ion
Which is one negative charge
–
9 protons (+)
10 electrons (–)
–
–
–
+++++++++
––––––––––
– Net charge: –
Net charge: –1
–
Net charge: –
–
–
9p
10 n
–
–
a fluoride
ion
–
9 protons (+)
10 electrons (–)
–
So we can say that the net charge on this ion is negative 1
–
–
+++++++++
––––––––––
– Net charge: –
Net charge: 1–
–
Net charge: –
–
–
9p
10 n
–
–
a fluoride
ion
Or 1 negative
–
9 protons (+)
10 electrons (–)
–
–
–
+++++++++
––––––––––
– Net charge: –
Net charge: 1–
–
Net charge: –
–
–
9p
10 n
–
–
a fluoride
ion
–
9 protons (+)
10 electrons (–)
–
Which is usually expressed simply as negative.
The ion charge
–
–
+++++++++
––––––––––
– Net charge: –
Net charge: 1–
–
Net charge: –
–
–
9p
10 n
–
–
a fluoride
ion
–
–
In the box on the periodic table, the top right hand corner shows the charge on the
most common ion of fluorine. We see it is (click) minus 1
The ion charge
–
–
+++++++++
––––––––––
– Net charge: –
Net charge: 1–
–
Net charge: –
–
–
9p
10 n
–
–
a fluoride
ion
–
–
Which is the same as the minus 1 charge shown here for our fluoride ion.
Group 17 (Halogens) all
gain one electron to form
an ion with a
– charge
Looking on the periodic table, we see that Group 17 nonmetals, or halogens all gain
1 electron (click) to form an ion with a negative 1 charge.
The top four Group 16
nonmetals all gain two
electrons to form an ion
with a
2– charge
The top 4 Group 16 nonmetals all gain 2 electrons (click) to form an ion with a
negative 2 charge.
The top three Group 15
nonmetals all gain three
electrons to form an ion
with a
3– charge
And the top three Group 15 nonmetals all gain 3 electrons (click) to form an ion with a negative
3 charge. In general, nonmetal atoms gain electrons in order to form stable negative ions.