*
UNIT 1: ST SCIENCE 10
-
ATOMIC MODELS
PERIODIC TABLE OF ELEMENTS
REPRESENTING MODELS
* AN ATOM IS THE SMALLEST PARTICLE OF
MATTER.
* IT CANNOT BE DIVIDED CHEMICALLY
* HOW SMALL IS AN ATOM?
- A SHEET OF PAPER IS ABOUT A MILLION
ATOMS THICK
- A DROP OF WATER CAN CONTAIN MANY
AS 10 SEXTILLION ATOMS.
(10000000000000000000000)
-THE DIAMETER OF THE PERIOD AT THE
END OF THIS SENTENCE HAS 50 TRILLION ATOMS
LINED UP IN A ROW IN IT
*
* DALTON’S MODEL 1808
SOLID BALLS. DIFFERENT COLORS. DIFFERENT MASSES
CARBON
OXYGEN
- ALL ATOMS OF THE SAME ELEMENT ARE THE SAME
- ALL ATOMS OF ONE ELEMENT ARE DIFFERENT FROM
THOSE OF OTHER ELEMENTS
- ELEMENTS CAN COMBINE
*
* THOMSON’S MODEL 1897
INCLUDED POSITIVE (PROTONS) AND NEGATIVE
(ELECTRONS) CHARGES.
ZINC
COPPER
- ADDED TO DALTON’S THEORY THAT ELEMENTS
HAD BOTH POSITIVELY CHARGED AND NEGATIVELY
CHARGED PARTS TO THEIR CORE
*
* RUTHERFORD’S MODEL 1911
FIRST TO INTRODUCE THE NUCLEUS,
LIGHTWEIGHT WITH NEGATIVE CHARGED
ELECTRONS SCATTERED RANDOMLY IN A LARGE
SPACE OUTSIDE THE NUCLEUS.
BERYLIUM
*
BERYLIUM
* RUTHERFORD-BOHR MODEL 1913
SMALL NUCLEUS(PROTONS AND NEUTRONS),
MORE CONSISTENT ELECTRONS IN A SERIES OF
ORBITS.
LITHIUM
*
NICKEL
* METALS, NONMETALS, AND METTALOIDS
* METALS
- IDENTIFIED BY THE STAIRCASE SHAPED LINE THAT CROSSES
THE RIGHT HAND SIDE OF THE TABLE.
- METALS: GOOD CONDUCTORS OF ELECTRICITY AND HEAT.
MALLEABLE AND DUCTILE SO THEY CAN BE EASILY SHAPED.
- SHINY
- ROOM TEMPERATURE THEY ARE SOLIDS (EXCEPT MERCURY)
- THEY REACT WITH ACIDS
*
* METALS, NONMETALS, METALLOIDS
* NONMETALS
- POOR CONDUCTORS OF ELECTRICITY AND HEAT
- MOST ARE GASES AT ROOM TEMPERATURE
- SOLID NONMETALS CAN BE REDUCED TO POWDER
*
* METALS, NONMETALS, METTALOIDS
* METTALOIDS
- (ALSO CALLED SEMI-METALS)
- SEVEN ELEMENTS WITH PROPERTIES OF BOTH
METALS AND NONMETALS.
- SOME CONDUCT WELL, SOME DON’T. FOR THIS
REASON THEY ARE SEMI-CONDUCTORS USED IN
TRANSITORS, INTEGRATED CIRCUITS, AND
LASERS
*
* GROUPS
- THEY CORRESPOND TO THE COLUMN IN THE PERIODIC
TABLE.
- EACH GROUP SHARE A SET OF SIMILAR CHEMICAL
PROPERTIES BECAUSE THEY ALL HAVE THE SAME NUMBER
OF VALANCE ELECTRONS.
- VALANCE ELECTRONS (THE NUMBER OF ELECTRONS IN
THE OUTERMOST SHELL)
2 – 8 – 8 – 18 ETC
*
* GROUPS
- ALAKALI METALS
ALL THE METALS OF THE 1ST GROUP. SOFT AND HIGHLY
REACTIVE. IN PURE STATE, THEY MOST BE STORED IN OIL
- ALKALINE EARTH METALS
ALL THE METALS IN THE 2ND GROUP. HIGHLY MALLEABLE
AND BURN EASILY IN THE PRESENCE OF HEAT.
- HALOGENS
NONMETALS IN GROUP 17. THEY REACT EASILY TO FORM
COMPOUNDS (SALTS AND DISINFECTANTS)
- NOBLE GASES
RARE GASES OR INERT GASES. LAST COLUMN. VERY STABLE.
THEY REACT MINIMALLY
*
* PERIODS
CORRESPONDS TO THE ROW OF THE PERIDIC TABLE. ALL THE
ELEMENTS HAVE THE SAME AMOUNT OF ELECTRON SHELLS
HAVE CORRESPONDING REPETITION IN THE PATTERNS OF THEIR
PROPERTIES (P. 23)
MELTING POINT – TEMPERATURE OF SOLID TO LIQUID
BOILING POINT – TEMPERATURE OF LIQUID TO GAS
DENSITY – MASS PER UNIT OF VOLUME
ATOMIC RADIUS – DISTANCE FROM CENTER OF THE ATOM
FIRST IONIZATION ENERGY – ENERGY REQUIRED TO REMOVE
OUTERMOST ELECTRON
ELECTRONEGATIVITY – ATTRACTING TO FORM BOND
*
* ATOMIC NUMBER
REPRESENTS THE NUMBER OF PROTONS IN THE
NUCLEUS OF AN ATOM
* ATOMIC MASS
REPRESENTS THE RELATIVE MASS OF THE ATOM
AN ELEMENT BASED ON CARBON’S 6 PROTONS
AND 6 NEUTRONS MEASURING 12u
* ISOTOPES
ADDED OR SUBTRACTED NEUTRONS DEPENDING
ON THE ELEMENT
*
* LEWIS NOTATION (P. 27)
A SIMPLER REPRESENTATION OF THE ATOM, IN WHICH
ONLY THE VALENCE ELECTRONS ARE ILLUSTRATED.
*
* RUTHERFORD-BOHR MODEL (P. 28)
ALL THREE FACTS MUST BE REPRESENTED:
1- THE PERIOD (REPRESENTING THE NUMBER OF ELECTRON
SHELLS IN THE ATOM)
2- THE GROUP (REPRESENTING THE NUMBER OF VALENCE
ELECTRONS)
3- ATOMIC NUMBER(REPRESENTING THE NUMBER OF
PROTONS AND ELECTRONS)
*
* SIMPLIFIED ATOMIC MODEL (P. 28)
WE ROUND THE MASS TO THE NEAREST WHOLE NUMBER.
WE SUBTRACT MASS – ATOMIC NUMBER TO FIND HOW MANY
NEUTRONS THERE ARE
EXAMPLE: CHLORINE 35.45u = 35
35 – 17 = 18 THEREFORE 17 PROTONS 17 ELECTRONS 18 NEUTRONS
*
* BALL AND STICK MODEL
BALLS WILL MAKE UP THE ELEMENTS
STICKS WILL MAKE UP THE BONDS
*