What is a trend? What do the terms group and period mean? What are synonyms for those terms? Who is considered the greatest contributor to the current periodic table?

Dmitri Mendeleev Produced first Periodic Table of the Elements. Properties of elements was a function of atomic mass Similar properties occurred after periods (horizontal rows) that varied in length Left spaces for elements that had not yet been discovered and predicted the properties of those elements Broke from order of increasing atomic mass in some areas to keep elements with same properties in the same column

MetalsNonmetals Hard, shiny, conduct heat and electricity Most solid at room temperature (Hg – liquid) Lose electrons to form positive ions Generally poor conductors of heat and electricity At room temperature, many are gases, some brittle solids, (Br – liquid) Gain electrons to form negative ions

He s p d f

GROUP (or family) - Column PERIOD - Row

Alkali metals Alkaline Earth Metals Transition Metals Inner Transition Metals Halogens Noble Gases

Write out the electron configuration for Lithium, Li Rubidium, Rb Oxygen, O

What is a trend ? Atomic Radius Ionization Energy Electronegativity

Atomic Radius Distance from nucleus to outermost electron Down a Group- Increases due to addition of energy levels Across a Period – Decreases due to greater nuclear charge

Positive ion smaller than atom since ion loses an energy level Negative ion larger than atom since ion has more electrons to attract Distance from nucleus to outermost electron in an ion Ionic Radius ATOM + - < << <

Ionization Energy Energy to lose an electron and form a positive ion Down a Group- Decreases due to shielding Across a Period – Increases due to greater nuclear charge

Electronegativity Ability to attract electrons in a chemical bond Down a Group- Decreases due to shielding Across a Period – I ncreases due to greater nuclear charge