The Periodic Law
(Periodic Table)
CHAPTER FIVE
Brief History
Original periodic table was constructed by
Dmitri Mendeleev. This periodic table
consisted of about 60 elements and was
arranged in order of increasing atomic
mass
Modern Periodic Table
• Our periodic table is based on the work of
Henry Mosely, who arranged the
elements in order of increasing atomic
number
Periodic Law
• Mosely’s and Mendeleev’s periodic table
follows periodic law:
• This means that if elements are arranged
in increasing atomic #, they will fall into
groups that have similar properties.
Modern Periodic Table
• 18 vertical group/families
• 7 horizontal periods
• Divided into two main parts, metals and
nonmentals.
Group 1 Elements
• Alkali Metals
– Most reactive of the metals
– Mostly Soft Solids
Group 2 Elements
• Alkaline Earth Metals
– Still very reactive
– More dense than the group 1 metals
Groups three through twelve
• Transitional Metals
• Elements “transition” from Metals to non-metals
as you move across the table
• metallic properties
Group 17
• Halogens
– Non-metals
– most reactive of nonmetals.
Group 18
• Noble gases
– Nonmetals
– Least reactive of non-metals
Left Side of the periodic table
• Metals
– Shiny
– Malleable
– Ductile
– Conducts electricity
– Conducts Heat
– Mostly solids
Inbetween are the “Others”
– Other Metals (Have metallic properties)
• Al, Ga, In, Sn, Bi, Pb, Tl
– Metalloids-Boron, Silicon, Germanium,
Arsenic, Antimony, Tellurium, Polonium
• Properties of both metals and non-mentals
• Semiconductors-used in electronics
– Other Non-Metals (Have non-metal properties)
• C, N, O, P, S, Se, H
Right side of periodic table
• Non-Metals
– Do not conduct electricity or heat well
– Some brittle solids
– Some gasses
Check for understanding
Which group/family
is each element in?
1.Al
2.Ar
3.K
4.Pd
5.Br
6.Ca
7.Zn
8.Si
Based on the
group/family each
element below are in,
name 2 properties of :
9. K
10. P
11. Cl
12. Ga
Periodic Trends
Elements have characteristics that tend to
increase or decrease as one moves along
a row or column of the periodic table of
elements.
Atomic Radii
• Atomic Radii-The distance from the center
of the nucleus to the edge of the atom’s
electron cloud.
Atomic Radii
Atomic Radii Trending Activity
• Grapher
• Straw Cutter
• Recorder
• We will use our current knowledge of the atom to try
and predict the trend for atomic radii.
• We will then test our hypothesis by actually graphing
real data and then making a 3-D model of the trend.
Atomic Radii Continued
• Trend in each period
– Why do you think the radius decreases to the
right if there are more protons to the right?
Shouldn’t that make the radius increase?
• As there are more protons they pull more strongly on
the electrons that are surrounding them.
• Each period is within the same energy level.
Atomic Radii Continued
• Trend in each group
– Why do you think the radius increases as you go down
a group if more protons means they pull harder on the
electrons?
– As you go down a group you are adding energy levels
which makes the radius increase.
Atomic Radii Continued
• Periodic Table Trend:
Increasing Size
– Increases to the left
– Increases going down
Atomic Radii Practice
In each pair which of the following has the largest Atomic Radii?
1. K or Ni
2. Ne or Xe
3. Rb or In
Arrange the following in order of increasing atomic radii?
4. Al, K, Ne, H
5. Will a larger atomic radii make an atom more or less likely
to give away an electron?
Quiz
1. Place the following in order using decreasing Atomic
Radii : Au, Ba, O, Cl & Pb
2. Cl or I
a) Which of the above pair has the largest atomic radii?
b) Why does the table trend that way?
3. Who created the 1st periodic table?
4.
5.
6.
7.
What was the 1st periodic table arranged by?
The vertical columns are called what?
Elements within the same column will have _________ properties.
What is the name of each of the following groups?
a)
b)
c)
18
2
1
8. Which group name does Ge fall under?
a)
Name 4 popertiesA
Ionization Energy (IE)
• 1st Ionization Energy-Energy required to
remove one electron from an un-bonded
atom. (individual atoms)
– Basically: How hard is it to get an electron
away from an atom?
No, Mine!
Mine!
e-
Ions
• ION-an atom that has a positive or negative
charge.
Ionization Energy (IE)
• A lost electron will create a Positive Ion
– Positive Ion is a Cation
+
+
+
+
+
Pawsitive : )
+
+
Ionization Energy (IE)
• A gained electron will create a negative ion
– Negative ions are called Anions
Ionization Energy (IE) Continued
• Trend across a period?
– Decreases to the left
• Trend in a group/family?
– Decreases going down
• Which Group would have the lowest first Ionization
energy? (who is it easiest to take an electron from?)
– Group 1
– Why?
• They want to get rid of that 1 valence electron
• Which group would have the highest first ionization
energy?
– Group 18
– Why?
• They do not want to lose one of their 8 valence
electrons ( they are happy the way they are)
Ionization Energy
• Periodic Table Trend:
– Decreases to the left
– Decreases going down
Decreasing
Decreasing
Ionization energy practice
• Which element within the following pairs has the
highest ionization energy?
– K or Be
– B or Ga
– O or Ca
– Ar or Sb
• Arrange the following in decreasing Ionization
energy (meaning from Highest to lowest)
– Li, O, C, K, Ne, F
Electronegativity
• Electronegativity-Measurement of how
strongly one atom attracts the electrons of
another atom in a compound.
• Developed by Linus Pauling
• Which element do you think would be the
most electronegative?
– Fluorine-4.0. All other values are calculated
in relation to Fluorine’s value.
– Scientest just picked the number 4. It wasn’t
really based on anything.
Electronegativity & (FON)
• Oxygen, Nitrogen and then the other
halogens are the most Electronegative
after fluorine.
• F, O, N – Top 3 highest electronegativity
Electronegativity
• Periodic Table Trend:
– Decreases to the left
– Decreases going down
Decreasing
Decreasing
Electronegativity Practice
1. Which of each pair has the greatest EN?
a. Ca or Ga
b. Br or As
c. Li or O
d. Ba or Sr
e. Cl or S
f. O or S
2. Rank the following elements by increasing EN:
sulfur, oxygen, neon, aluminum.
– Answer: Ne,Al,S,O
Trending Challenge
Terms
Atomic Radii
Ionization
Energy
Electronegativity
Definition in your
own words
Single
atoms or
bonded
atoms?
Element with
smallest
Element with
largest
Review
1. The elements characterized as nonmetals are located in the periodic table at the
(A) left; (B) bottom; (C) center; (D) top right
2. Which is the atomic number of an alkali metal?
(A) 10; (B) 11; (C) 12; (D) 13.
3. Which element is a halogen?
(A) iron; (B) nitrogen; (C) iodine; (D) neon
4. Which Group 17 element has the least tendency to gain electrons?
(A) fluorine; (B) iodine; (C) bromine; (D) chlorine.
5. The alkaline earth element having the largest atomic radius is found in Period
(A) 1; (B) 2; (C) 6; (D) 7.
6. Which of the following atoms will lose an electron the easiest?
(A) potassium; (B) calcium; (C) rubidium; (D) strontium
Electron Affinity
• Electron Affinity-The energy change that occurs
when an individual atom gains an electron.
– The more an atom “loves” getting another electron the
more the energy it will release.
..
+
Atom
._
.
Electron
Electron Affinity
• Which group is “happiest” to take on an electron?
– Group 17 Why?
– They are 1 electron away from a full outer shell
(Valance Shell)
Electron Affinity
• Which groups care nothing for additional electrons?
• Group 1 and Group 18? Why?
– Group 18 is totally happy with their 8 electrons
– Group 1 is closer to being happy by giving away
it’s 1 valance electron.
Electron Affinity
• Periodic Table Trend:
– Decreases to the left
– Decreases going down
Decreasing
Decreasing
Electron Affinity
• Which of the following has the greatest
electron affinity?
– Al or Br
– O or C
– Xe or F
• Arrange by increasing Electron Affinity
– Cl, K, Fr, I
• Answer:Fr, K, I, Cl