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The Ancient ModelGreeks were first to consider
the fundamental nature of matter.
Cut something in half enough times
eventually it becomes a single uncuttable piece.
The ATOM (atomos = greek for “uncuttable”
JJ Thompson - The “Plum Pudding” model
Positive charge sphere (the pudding)
Studded with negative charge electrons (the raisins)
Used Cathode Ray Tubes and measured deflection of particles
Ernest RutherfordDiscovered the Nucleus!
Alpha Particles shot at gold foil were expected to pass right through
Instead a small percentage of them were deflected!
This meant there had to be a concentration of mass at the center!
James ChadwickDiscovered the Neutron!
Beryllium was bombarded with radiation
It emitted particles with NO charge (neutral)
Today’s Quantum ModelThe electron “cloud” model
Electrons do not “orbit” the nucleus like planets
They have “regions of probability”
This is where electrons are LIKELY to be found.
They move too fast to observe continuously!
Families on the Periodic TableElements on the periodic table have been
grouped into families based on their chemical properties.
Each family has a specific name to differentiate it from the other families in the periodic table.
Elements in each family react differently with other elements.
Basic classificationsMetals – Shiny, silver/grey/whitish, good
conductors, malleable, high melting pointsNonmetals – Dull, low melting points, poor
conductors, brittle, Metalloids – Not metals, but not nonmetals
either… properties of both!
ALKALI METALSGroup 1Hydrogen is not a member, it
is a non-metal (but also a Metal)
1 electron in the outer shell
Soft and silvery metals
Very reactive, esp. with water
Conduct electricity
ALKALINE EARTH METALSGroup 22 electrons in the
outer shell
White and malleable
Reactive, but less than Alkali metals
Conduct electricity
TRANSITION METALSGroups in the
middle
Good conductors of heat and electricity.
Some are used for jewelry.
Can bond with many elements in a variety of shapes.
BORON FAMILY Group 33 electrons in
the outer shellMost are metalsBoron is a
metalloidAluminum is on
the metal/non-metal border, but is NOT a metalloid!
CARBON FAMILY Group 44 electrons in
the outer shell
Contains metals, metalloids, and a non-metal Carbon (C)
Si and Ge vital to the information age (computers)
NITROGEN FAMILY Group 55 electrons in
the outer shellEasily share
electrons to form compounds (N and P especially)
Contains metals, metalloids, and non-metals
OXYGEN FAMILY Group 66 electrons in
the outer shellContains
metals, metalloids, and non-metals
Reactive
HalogensGroup 7All are non-metals
(Astatine is a metalloid)
One electron away from full outer shells!
Very reactive are often bonded with elements from Group 1
Like NaCl (Table salt!)
Noble GasesGroup 8Exist as gases
Non-metals
Full Outer electron shells, they don’t want to share!
Not reactive with other elements
Rare Earth MetalsMany are
Radioactive
The rare earths are silver, silvery-white, or gray metals.
Conduct electricity
Large Nuclei!