ANSWER KEY
Element
Li
N
O
Ca
Br
S
Cl
K
Mg
Be
# Valence Electrons
1
Ions Worksheet
# Electrons to gain # Electrons to lose
None
1
5
6
2
3
i
None
None
2
None
None
None
1
i
i
None
1
2
7
6
7
1
2
2
1
None
None
None
Ion Formed/ name
Li + / cation
N ~ " / anion
0"" /anion
Ca"' /calion
Br" /anion
S;" /anion
Cl" /anion
K * /cation
Mg"* /cation
Be" /cation
Questions:
1. If Li loses an electron to another atom, why is it written L i + 1 (with a +1)?
It will have 3 protons (+), but only 2 electrons (-), so it will have a positive charge of 1.
2. If N gains 3 electrons from other atoms, why is it written N'3 (with a -3)?
It will have 7 protons (•»•), and 10 electrons (-), so it will have a negative charge of 3.
3. a. What do you think happens to atomic radius size of a cation <& why? B. an anion <St why?
a. Nations lose their outer most energy level , so the atomic radius will decrease
b. Anions gain electrons, so they will have more electrons than protons. This makes the
attraction between protons <& electrons weaker and the electrons can move farther away from
the nucleus, causing the radius to increase.
and
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Name:
Date:
R
Cation-Anion Worksheet:
Neutral Atoms Forming Ions
Atoms never have more than 8 valence electrons.
Atoms with fewer than 4 valence electrons tend to lose these electrons to become cations (positive).
Atoms with greater than 4 valence electrons tend to gain more electrons for a total of eight becoming anions
(negative).
Below write out equations showing whether an element gains or loses electron. Be sure to indicate how many
electrons are gained or lost. Indicate if the final ion is a cation or anion.
Type of Ion
1.
K
loses le-
—P K+
6
2.
0
gains 2e~ —^7 O2"
2
3.
Mg
3
4.
Al
1
6
5.
3
-9
Anion
CatTtn
- —^) A 1$
z
/3
s
6.
7.
Cation
MaC-t\Ji
Na
N
CflrfTdX
7
/5
rz
2
9.
Ba
7
7
1
10.
Br
11.
1
12.
Ra
«3L
7
i
13.
Ca
(3*. —7
14.
Cl
15.
Sr
Cf-f5r
'7
2
16.
P
-t
/5
S
-H J
J
2
-7
3-*""-)
17. Are anions metals or nonmetals?
18. Are cations metals or nonmetals?
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