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4.8  Trends in Periodic Properties 4.8  Trends in Periodic Properties

4.8 Trends in Periodic Properties - PowerPoint Presentation

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4.8 Trends in Periodic Properties - PPT Presentation

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.

Slide2

Group 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

Slide3

Valence Electron Configurations

Valence Electron Configuration for Representative Elements in Periods 1 to 4

Slide4

Study Check

Using the periodic table, write the group number, the period, and the valence electron configuration for the following:

A

. calcium

B.

lead

Slide5

Solution

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

.

Slide6

Lewis 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

Slide7

Lewis Symbols

Lewis Symbols for Selected Elements in Periods 1 to 4

Slide8

Study Check

Write the electron-dot symbol for each of the following elements:

Cl

, C, N

.

Slide9

Solution

Write the electron-dot symbol for each of the following elements: Cl, C, N.

Slide10

Atomic 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

Slide11

Atomic Size

For representative elements, the atomic size increases going down a group but decreases going from left to right across a period.

Slide12

Ionization 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.

Slide13

Ionization Energy

Ionization energy decreases down a group and increases going across a period from left to right.

Slide14

Metallic 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.

Slide15

Metallic Character

The metallic character of the representative elements increases going down a group and decreases going from left to right across a period.

Slide16

Summary of Trends in the Periodic Table

Slide17

Study 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)?

Slide18

Solution

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

Slide19

Study 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

_______

.

Slide20

Solution

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

.

Slide21

Concept Map