The Periodic Table of Elements. Periodic Table Arranged by Russian chemist Dimitri Mendeleev (late 1800’s) Arranged by Russian chemist Dimitri Mendeleev.

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