Answer KEY
Unit 3 Outline/ Study Guide - Electron Configuration and Periodic Trends
Essential Skills/ State Standards:
1. Students know how to relate the position of an element in the periodic table to its quantum
electron configuration and to its reactivity with other elements in the table.
2. Students know how to use the periodic table to identify metals, semimetals, nonmetals, halogens,
alkali metals, alkaline earth metals, and transition metals.
3. Students know how to use the periodic table to identify the following trends:
ionization energy, electronegativity, and the relative sizes of ions and atoms
(this includes knowing the definitions of ionization energy, electronegativity, cation, and anion.)
Study Guide -(use your notes and worksheets for a more complete review)
1. Identify the following things on the periodic table:
-metals
metalloids
(semimetals)
transition
metals
nonmetals
-Periods
-alkali
metals
alkaline
earth
metals
halogens
-noble
gases
Groups/
families
Identify groups with
the following
numbers of valence
electrons:
1,2,3,4,5,6,7,8
2. Why do the elements in the groups (columns) behave so similar to each other even if they have great
differences in their number of protons?
same number of valence electrons and similar
chemical properties.
3. What is the connection between the following terms: octet rule, valence electrons, and ions?
In order to achieve the octet rule, atoms gain or lose their valence electrons. They become
charged ions when this occurs.
4. a. List the elements that are exceptions to the octet rule b) Why don’t these atoms achieve
the octet rule?
a. Small atoms are happy with 2 electrons (ex: H, He, Li, Be, B)
b. because the 1s energy level only holds 2 electrons
5.
a.
Isotope or Ion
atoms that have a different number of
neutrons
b. atoms have gained or lost electrons
Ion
Isotope
c. shown by putting a +/- sign next to an
element
(ex: Ca + 2)
d. shown by putting the mass in hyphen notation
(ex: C- 14)
Ion
Isotope
6. a. Which electron orbital has more energy, electrons in 3p or 5p?
Energy Level 5 has more energy because it’s further away from the nucleus & requires
more energy to put an electron there.
b. What atomic sublevel has the next highest energy after 2p and will fill next?
3 s.
c. Based on your lab experience, how does an electron become excited?
They gain energy from the Bunsen burner
d. When do you see the unique light pattern for each element?
when the electrons fall back down to a lower energy level they release the energy in the
form of light.
7.
a. Cation or anion? How do you
know?
b. Did they gain or lose electrons?
How do you know?
c. Which atom is larger or smaller in
size? How do you know?
O
-2
Mg
+ 2
Anion- negative charge
Cation- positive charge
Gained 2 more negative
electrons, thus they are more
negative by 2
Bigger, gained electrons
Lost 2 electrons, thus they
are more positive
Smaller, lost electrons
8.
Noble Gas Config.
[Ne]3s23p5
[Xe]6s24f145d106p3
[Ar] 4s23d104p5
[Ar]4s1
[Xe]6s24f145d106p4
9.
# valence
electrons
period
block
Group
number
7
5
7
1
6
3
6
4
4
6
P
P
P
S
P
17
15
17
1
16
Ion it will
form
Cl-1
Bi-3
Br-1
K+1
Po-2
Element
name
Cl
Bi
Br
K
Po
How many valence electrons does each of the following elements have?
a. noble gases= 8
b. alkali metals=1
c. halogens= 7
d. alkali earth metals= 2
10.
energy it takes to remove an electron from an atom
(Lowest= Fr Highest= He)
A. Ionization energy:
b. Identify the elements that have the highest & lowest ionization energy
Na, Cl, Mg, P
K, Na, Rb, Li
highest:
lowest:
highest:
Cl
11 A. Electronegativity:
Highest= F)
Na
Li
lowest:
Rb
an atoms ability to attract electrons to itself. (Lowest= Fr
b. Identify the most & least electronegative elements
Na, Ne, O, Al
Most:
least:
Ca, Cu, F, Ar
most:
least:
O
F
Ne
Ar
size of the radius of the atom (it’s actually defined as ½ the
distance between the nuclei of two atoms bonded together)
(Biggest= Fr smallest= He)
12. Atomic radius:
b. Identify the largest to smallest atoms based on atomic radius
Ti, P, Cs, Ne
Li, O, Cu, K
largest:
smallest:
largest:
smallest:
Cs
O
Ne
K
Naming/ Formulas:
13. A. What is the rule for naming/ formula writing for a metal + non-metal?
Full name & then Root + -ide ending. Formula writing= swap & drop the ion charges.
b. Give an example:
CaCl2
Calcium chloride
14. What is the rule for naming/ formula writing for 2 non-metals?
Prefix (except if only one) + full name & then Prefix + root + -ide ending
b. Give an example:
N2O3
Dinitrogen trioxide