http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Pe... [2]
http://en.wikipedia.org/wiki/Periodic_trends [3]
https://www.chem.tamu.edu/class/majors/tutorialnotefiles/trends.htm [4]
https://www.khanacademy.org/science/chemistry/atomic-structure-and-prope... [5]
http://chemistry.about.com/od/periodictableelements/a/periodictrends.htm [6]
http://edtech2.boisestate.edu/lindabennett1/502/Periodic%20Table%20e%20c... [7]
Links
[1] https://www.hootsgo.org/?q=node/6435
[2] http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Periodic_Trends_of_Elemental_Properties/Periodic_Trends
[3] http://en.wikipedia.org/wiki/Periodic_trends
[4] https://www.chem.tamu.edu/class/majors/tutorialnotefiles/trends.htm
[5] https://www.khanacademy.org/science/chemistry/atomic-structure-and-properties/periodic-table-trends-bonding
[6] http://chemistry.about.com/od/periodictableelements/a/periodictrends.htm
[7] http://edtech2.boisestate.edu/lindabennett1/502/Periodic%20Table%20e%20config/PTable_trends%20around%20table.html