Post on 14-Jan-2016
The Periodic Table of The Periodic Table of ElementsElements
Periodic TablePeriodic TableArranged by Russian chemist Dimitri Arranged by Russian chemist Dimitri
MendeleevMendeleev (late 1800’s) (late 1800’s)Originally arranged Originally arranged
by increasing atomicby increasing atomic
massmassLater arranged by Later arranged by
increasing atomic #increasing atomic #
(Henry Moseley)(Henry Moseley)
ColumnsColumns
Known as Known as Groups or FamiliesGroups or Families
A group or family has A group or family has similarsimilar but but not identical propertiesnot identical properties
Example: Group 1 or Alkali MetalsExample: Group 1 or Alkali MetalsProperties – soft, white, shiny Properties – soft, white, shiny
metals, highly reactive metals, highly reactive
We Are Family!We Are Family!
Periodic Table
Organized into
Rows = Periods
Columns = Groups or Families
Special GroupsSpecial Groups
Group 1 – Alkali MetalsGroup 1 – Alkali MetalsGroup 2 – Alkaline Earth MetalsGroup 2 – Alkaline Earth MetalsGroup 17 – HalogensGroup 17 – HalogensGroup 18 – Noble GasesGroup 18 – Noble Gases
Metals/Non-metals
Notice the Notice the dark dark
stairstep stairstep line.line.
Separates Separates metals metals from from
nonmetalsnonmetals
Metals/Metalloids/Nonmetals
MetalsMetalloids
Properties between metals and nonmetals
Have a side touching the stairstep line EXCEPT Al (metal)
Nonmetals
RowsRowsKnown as Known as periodsperiods
Are not alike in properties, but there Are not alike in properties, but there is a patternis a patternThe first element in a period is The first element in a period is almost always a reactive solidalmost always a reactive solid
The last element is an inert or The last element is an inert or inactive gasinactive gas
Group Practice
Give the group number for each element:CalciumTelluriumCesiumChlorineArgon
RowsRows
Each period tells you how many Each period tells you how many energy levels each atom hasenergy levels each atom hasEach energy level can hold a Each energy level can hold a certain number of electronscertain number of electronsEnergy level 1 - 2 electronsEnergy level 1 - 2 electronsEnergy level 2 - 10 electronsEnergy level 2 - 10 electronsEnergy level 3 - 18 electronsEnergy level 3 - 18 electrons
Practice
Give the element from the periodic table:Period 2, Group 14Period 4, Group 3Period 3, Group 17Period 1, Group 8Period 4, Group 2Period 2, Group 4
Why do we care about how many Why do we care about how many electrons an atom has?electrons an atom has?
The The reactivityreactivity of an element is due to its of an element is due to its valencevalence electrons electronsValence electrons are the electrons Valence electrons are the electrons
found in the outer shell of an atom.found in the outer shell of an atom.
Valence Electrons
NucleusShell or Energy Level
Trick to the Dot DiagramsTrick to the Dot DiagramsSome atoms are very easy to figure out how Some atoms are very easy to figure out how
many electrons are in the many electrons are in the valencevalence shell shellGroup 1 has 1Group 1 has 1Group 2 has 2Group 2 has 2Group 13 has 3Group 13 has 3Group 14 has 4 (are you noticing a pattern yet?)Group 14 has 4 (are you noticing a pattern yet?)Group 15 has 5Group 15 has 5Group 16 has 6Group 16 has 6Group 17 has 7Group 17 has 7Group 18 has 8Group 18 has 8
Groups 3-12 always have 2 electronsGroups 3-12 always have 2 electrons
Dot DiagramsDot Diagrams
A diagram to represent A diagram to represent electrons in the electrons in the outer energy levelouter energy level of an atom of an atomUses the atomic symbol and dotsUses the atomic symbol and dots
Example: Hydrogen Example: Hydrogen H H••
BerylliumBeryllium BeBe::
Carbon Carbon :: C C ::
Dot Diagram How-To
1. Figure out how many valence electrons the atom has.
2. Write the symbol for the element.
3. Add dots in pairs on each side of the symbol (imagine that it is inside a box) to represent the valence electrons.
Example: Silicon 4 valence electrons
Dot Diagram Practice
Draw Dot Diagrams for each of the following:
HydrogenChlorineCalciumNitrogenAluminum