Patterns in the Periodic Table Nelson: Science Perspectives 9 – Pg. #

Learning Goals: Describe a “chemical family” and explain the significance in regards to the periodic table Define a “period” in regards to the periodic table Discuss how the periodic table has evolved over time

Chemical Families Chemical Family  a column of elements with similar properties on the periodic table Chemical families with distinctive properties that have specific names The columns are numbered from left to right

Chemical Families

Alkali Metals Elements in Group #1 of the periodic table EXAMPLES: lithium (Li), sodium (Na), and potassium (K) Highly reactive (often combine with other elements/compounds - don’t often find them on their own) Shiny, silvery, soft, relatively low densities (float on water) EXAMPLES: salt (NaCl) and baking soda (NaHCO 3 )

Alkaline Earth Metals Elements in Group #2 of the periodic table EXAMPLES: beryllium, magnesium, calcium, strontium, barium, and radium Not as soft or reactive as alkali metals Shiny, silvery Burn with bright, colourful flames (often used in fireworks)

Transition Metals Elements found in Groups # Good conductors of heat and electricity Includes metals used in jewelry and construction. Less reactive harder metals - Metals used “as metal.”

Noble Gases Elements in Group #18 of the periodic table EXAMPLES: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) Very stable and unreactive Colourless, odourless, tasteless Glow brightly when electricity is passed through

Halogens Elements in Group #17 of the periodic table EXAMPLES: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (at) Very reactive (rarely found in elementary form – often form compounds with alkali metals)

Rare Earth Metals Some are Radioactive

Periodic Trends Period  a row on the periodic table The term “period” refers to cycles (THINK: recurring classes in daily school schedule) Elements in the same horizontal row show trends of increasing/decreasing reactivity

Colour in the Chemical Families

History of the Periodic Table Dmitri Mendeleev originally created the first periodic table in 1869 Arranged elements (63 at the time) by their known mass Started with lightest (hydrogen) Noticed groups of elements had similar physical/chemical properties to arranged elements with similar properties under each other (columns)  thus irregular shape of current periodic table Was able to accurately predict properties of unknown elements using this table

Solving the Puzzle Periodically Cut out all of the pieces on the provided handout. Arrange the pieces based on their various properities Once arranged in rows/columns, predict the properties of the unknown/missing piece.

Extra Work Complete the questions on page 225.