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

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.

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: Largest Radius Small Radius Small 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

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