Periodic Trends

Compiled by R. Erwin Rockwall ISD

Periodic Table

• The Periodic Table of the Elements we use today is credited to Dimitri Mendeleev.

• It is arranged in Columns and Rows• Columns are called “Groups” or “Families”• Rows are Called “Periods”

• The Periodic Table reflects all of the known elements.• Useful in predicting:

• Chemical properties of the elements • Trends• Behavior of elements + +Some information from Cscope

Periodic Table - Groups Groups (or “Families”) – Vertical (Y-axis)

columns of elements

Numbered from 1 – 18 Elements in a group are most similar in

behavior and properties. Behave alike because all elements in a

group have the same number of valence electrons.

Radius of atom increases as go down the column

As add more energy rings

http://www.tutorvista.com/content/science/science-ii/periodic-classification-elements/trends

Periodic Table - Periods Periods – Horizontal (X-axis) rows of elements

Atomic Numbers increase in increments of 1 proton from left to right

+1 so Atomic Number increases by +1

Atomic mass also increases

All elements in the same period have the same number of energy rings.

http://www.tutorvista.com/content/science/science-ii/periodic-classification-elements/trends.php#number-of-shells-in-a-group-increase

Table Trends-Overview

Radius – distance from the center of the nucleus to the outer most shell of an atom Radius of atoms Decrease from left to right

Due to increasingly tighter bonds as add protons

Ionization Energy –the amount of energy needed to rip an electron away from an atom

Electronegativity – The ability to form compounds.

Electron Affinity – the energy change when an electron is added to a gaseous neutral atom

Metallic Properties – Element’s ability to conduct energy

Table Trends- Radius Radius – distance from the center of the

nucleus to the outer most shell of an atom Radius of atoms Decrease from left to right

Due to increasingly tighter bonds as add protons

Radius of atoms Increase as you go down the column Due to adding of energy levels

Table Trends-Radius Radius size works like this:

LargestRadius

Small RadiusSmall

Radius

Larger Radius

Table Trends-Radius Or this

Table Trends- Ionization Energy

Ionization Energy – the amount of energy required to rip an electron away from an atom. Harder going right across a period

Easier going down a group

Table Trends-Electron Affinity

Electron Affinity – the energy change when an electron is added to a neutral atom Affinity (change) is greatest gong right across

a period, and up a group.

Greatest in upper right sections (Noble gasses)

Largest changes up and to right

Table Trends- Electron Affinity

Table Trends-Electronegativity

Electronegativity– the ability to attract and gain electrons to form compounds Increases gong right across a period and up a

group.

Greatest in upper right sections EXCEPT for Noble Gasses

Decreases gong left across a period and down a group.

Least in lower left metals in greater periods

Due to increasing distance from nucleus

http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Periodic_Table_of_the_Elements/Periodic_Trends#Periodic_Trends_for_Electronegativity

Table Trends-Electronegativity Electronegativity– the ability to attract and

gain electrons to form compounds

Table Trends- Metallic Properties

Metallic properties are the relative properties of elements to be good conductors of energy

This can be thermal energy (heat) or

Electrical energy (electricity)

Table Trends- Summary

One thing all trends have in common – All are related to the element’s properties, and its Valence Electrons.

We can tell much about an element by its place in the Periodic Table

Table Trends-Summary