The atomic size of representative elements is affected by the attractive forces between the protons in the nucleus and the electrons in the outermost energy level Learning Goal Use the electron configurations of elements to explain the trends in periodic properties ID: 759502
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Slide1
4.8 Trends in Periodic Properties
The atomic size of representative elements is affected by the attractive forces between the protons in the nucleus and the electrons in the outermost energy level.
Learning Goal Use the electron configurations of elements to explain the trends in periodic properties.
Slide2Group Numbers: Valence Electrons
For representative elements in Groups 1A (1)–8A (18), chemical properties are due to the number of valence electrons.Valence electrons are the number of electrons in the outermost energy level.The group number gives the number of valence electrons for the representative elements.
Core Chemistry Skill
Identifying Trends in
Periodic Properties
Slide3Valence Electron Configurations
Valence Electron Configuration for Representative Elements in Periods 1 to 4
Slide4Study Check
Using the periodic table, write the group number, the period, and the valence electron configuration for the following:
A
. calcium
B.
lead
Slide5Solution
The valence electrons are the outermost
s
and
p
electrons. Although they may have electrons in the
d
or
f
sublevel, they are not valence electrons.
A. Calcium is in Group 2A (2), Period 4. It has a valence electron configuration of 4
s
2
.
B. Lead is in Group 4A (14), Period 6. It has a valence electron configuration of 6
s
2
6
p
2
.
Slide6Lewis Symbols
Lewis symbols represent the valence electrons as dots placed on sides of the symbol for an element.One to four valence electrons are arranged as single dots.Five to eight valence electrons are arranged with at least one pair of electrons around the symbol for the element.Core Chemistry Skill Drawing Lewis Symbols
Lewis Symbols for Magnesium
Slide7Lewis Symbols
Lewis Symbols for Selected Elements in Periods 1 to 4
Slide8Study Check
Write the electron-dot symbol for each of the following elements:
Cl
, C, N
.
Solution
Write the electron-dot symbol for each of the following elements: Cl, C, N.
Slide10Atomic sizeis determined by the atom’s atomic radius, the distance between the nucleus and the outermost electrons.increases for representative elements from top to bottom of the periodic table.decreases within a period as a result of increased number of protons in the nucleus.
Atomic Size
Slide11Atomic Size
For representative elements, the atomic size increases going down a group but decreases going from left to right across a period.
Slide12Ionization Energy
Ionization energy is the energy required to remove one of the outermost electrons. Na(g) + energy (ionization) Na+(g) + e−As the distance from the nucleus to the valence electrons increases, the ionization energy decreases.The ionization energy is low for metals and high for the nonmetals.
Slide13Ionization Energy
Ionization energy decreases down a group and increases going across a period from left to right.
Slide14Metallic Character
An element with
metallic character
is one that loses valence electrons easily.
Metallic character
is more prevalent in metals on the left side of the
periodic
table.
is less for nonmetals on the right side of the periodic table that do not lose electrons easily.
decreases going down a group, as electrons are farther away from the nucleus.
Slide15Metallic Character
The metallic character of the representative elements increases going down a group and decreases going from left to right across a period.
Slide16Summary of Trends in the Periodic Table
Slide17Study Check
Given the elements C, N,
and
Cl
,
A. which is the largest atom?
B. which has the highest ionization energy?
C. which belongs to Group 5A (15)?
Slide18Solution
Given the elements C, N,
and
Cl
,
A. which is the largest atom?
C
B. which has the highest ionization energy?
Cl
C. which belongs to Group 5A (15)?
N
Slide19Study Check
Complete each of the following statements with
decreases
or
increases
.
A. Going down Group 6A (16), the ionization energy
_______
.
B. Going across Period 3, from left to right, the atomic size
_______
.
C. Going down Group 2A (2), the metallic character
_______
.
Slide20Solution
Complete each of the following statements with
decreases
or
increases
.
A. Going down Group 6A (16), the ionization
energy
decreases
.
B. Going across Period 3, from left to right, the atomic size
decreases
.
C. Going down Group 2A (2), the metallic character
increases
.
Slide21Concept Map