ATOMS AND ATOMIC THEORY
PERIODIC TABLE AND ITS PROPERTIES
CHEMICAL BONDS
THE ATOM
-The smallest piece of
matter that still retains
the property of the
element.
THE ATOM AND ITS PARTS
NUCLEUS
ELECTRON
CLOUD
E
E
P
N
E
ELECTRON (-)
NEUTRONS
(no charge)
ENERGY LEVEL
PROTONS (+)
QUARKS = particles that make up protons and
neutrons
-Quarks are held together by nuclear
forces
-6 Quarks = Proton
-3 Quarks = Neutron
-How do they know this?
-Look at picture on pg. 508
IDENTIFYING ATOMS
ATOMIC NUMBER
6
-# of protons
Carbon
-# of electrons
C
-Tells you what type of
atom you have
12
ATOMIC MASS
-# of protons + # of neutrons
-AMU = atomic mass unit =
unit of measurement
# of Neutrons = mass # - atomic #
BOHR MODELS and ELECTRON DOT DIAGRAMS
-Show how electrons are arranged in energy levels.
-Use: 2n2
-Use:
Atomic #
e
P/N
e
Na
Cl
Stable Atoms:
-Have 2 e if
they only have 1
shell
-Have 8 e if
they have more
than 1 shell
Electron-dot diagrams use the elements
symbol and dots to show the # of electrons in
EVOLUTION OF THE
ATOMIC MODEL
Famous Dead Guy = Democritus
Time Period = 400 BC
Experiment = None/Philosopher in Greece – He reasoned that
all substances were made up of ATOMS
Results = Atoms were solids that couldn’t be subdivided =
“UNCUTTABLE” ATOM
EVOLUTION OF THE
ATOMIC MODEL
Famous Dead Guy = John Dalton
Time Period = 1800s
Experiment = Wanted to explain how and why elements
combine together in fixed ratios, so he developed a theory
Results = Theory states: Each element has its own atoms which
can rearrange/recombine with other atoms in chemical
reactions. Idea of the atom = SOLID SPHERE
EVOLUTION OF THE
ATOMIC MODEL
Famous Dead Guy = John Thomson
Time Period = 1904
Experiment = Used cathode-ray tubes with beams of electrons
inside. The electrons were attracted to positive charges within
the tube.
Results = The atom was a ball of positive charges with small
negative particles called electrons **DISCOVERED THE
ELECTRON*** Model of the atom = PLUM PUDDING
MODEL
EVOLUTION OF THE
ATOMIC MODEL
Famous Dead Guy: Ernest Rutherford
Time Period: 1911
Experiment:Shot alpha particles
(positive charges) through Gold Foil.
Some passed straight thru, others
bounced off at angles
Results: Said the atom had a small core
of positive charge surrounded by
electrons
EVOLUTION OF THE
ATOMIC MODEL
Famous Dead Guy: Niels Bohr
Time Period: 1913
Experiment: Noticed that each
element had its own line spectra
(light).This meant atoms could give
off energy.
Results: Electrons exist on energy
levels. When they get excited, the
jump up a level and emit light.
EVOLUTION OF THE
ATOMIC MODEL
- Electron Cloud Model = Current = ELECTRON CLOUD
= electrons don’t travel on orbitals. Electrons are found
in the electron cloud = area around nucleus where
electrons are most likely found.
Each level of an atom can only hold
a specific amount of electrons:
2n2
1st level: n=1: 2(1)2 = 2 electrons
2nd level: n=2: 2(2)2 = 8 electrons
3rd level: n=3: 2(3)2 = 18 electrons
4th level: n=4: 2(4)2 = 32 electrons
THE PERIODIC TABLE
-Periodic = “Repeated in a pattern”
-Ex: phases of the moon, days of the week, calendars
-Periodic Table = way to organize the elements using
patterns
-Developed by: Dmitri Mendeleev in the late 1800s
-Arranged in order of INCREASING ATOMIC # and
by CHANGES IN PHYSICAL AND CHEMICAL
PROPERTIES
-ATOMIC # always INCREASES from LEFT to
RIGHT
-As you go from the left to the right, one
proton and one electron are added to each
element!
THE PERIODIC TABLE
GROUPS: vertical columns
-AKA: FAMILIES
-# 1-18
-Elements in each group have SIMILAR
PROPERTIES
-Ex: Group II = shiny metals, good
conductors
-Elements in the same group have THE SAME #
OF ELECTRONS in their OUTTER ENERGY LEVEL
-This determines the CHEMICAL
PROPERTIES of the element
THE PERIODIC TABLE
PERIODS: horizontal rows
-Increase by one proton and one electron as
you go left-right
METALS: On the left side of the table up to the
metalloids
METALLOIDS: “Semimetals” - have properties of
metals and nonmetals.
-Form a downward staircase
NONMETALS: On the right side of the table
-Also includes Hydrogen (found on the left)
SYMBOLS: 1-2 letter abreviation of the element
GENERAL TRENDS IN THE
PERIODIC TABLE
ADD TO YOUR PERIODIC TABLE!!
-Electronegativity: An atom’s desire to GRAB
another atom’s electrons
-Periods: It INCREASES from LEFT
TO RIGHT
-why??
-Groups: It DECREASES as you GO
DOWN a group
-why??
GENERAL TRENDS IN THE
PERIODIC TABLE
-Ionization Energy: Amount of ENERGY required
to REMOVE the outermost ELECTRON
-RELATED TO ELECTRONEGATIVITY
-Periods: INCREASES from the LEFT to
the RIGHT
-Why?
-Groups: DECREASES as you go DOWN a
group
-Why?
GENERAL TRENDS IN THE
PERIODIC TABLE
-Reactivity: How LIKELY/vigorously an atom is to REACT with
other substances
-Determined by how easily electrons can be removed
(ionization energy) and how badly an atom wants to take other
atom’s electrons away (electronegativity)
-Metals:
-Periods: DECREASES from LEFT to RIGHT
-Groups: INCREASES as you go DOWN
-Nonmetals:
-Periods: INCREASES from LEFT to RIGHT
-Groups: DECREASES as you go DOWN
GENERAL TRENDS IN THE
PERIODIC TABLE
-Melting Point:
-METALS: DECREASES as you go DOWN
-NONMEALS: INCREASES as you go DOWN
PROPERTIES OF METALS
-Malleable = they can be HAMMERED into THIN SHEETS
-Ductile = they can be DRAWN into WIRES
-Most are HARD, SHINY SOLIDS
-GOOD CONDUCTORS of electricity
-Ex: Copper, Gold, Silver
-Some are MAGNETIC
-Ex: Cobalt, Nickel, Iron
METAL FAMILIES
1. ALKALI METALS (Group 1)
-1 valence electron (in their outer shell)
-Highly Reactive (want to give away their one electron
to become full and stable)
-Shiny, Malleable, and Ductile
-Good Conductors
-Never found alone in nature
because they are the most reactive metal
METAL FAMILIES
2. ALKALINE EARTH METALS (Group 2)
-2 valence electrons
-Very Reactive (want to give away their 2 electrons
to become full and stable)
-Shiny, Malleable, and Ductile
-Never found alone in nature)
METAL FAMILIES
3. Transition Metals (Groups 3B - 12B)
-1, 2, or 3 valence electrons
-Less Reactive than groups 1 and 2
-Some are MAGNETIC (Iron, Nickel, and Cobalt)
-Some are very good CONDUCTORS (Copper, Gold)
-MERCURY is the ONLY LIQUID METAL
METAL FAMILIES
4. Synthetic Elements (Manmade)
-Most are in Periods 6 and 7
-11 are in the ACTINOID and LANTHANOID series
-RADIOACTIVE
PROPERTIES OF
NONMETALS
-GROUPS 7A AND 8A
-SOLIDS, LIQUIDS, or GASES at room temp.
-DULL in color
-VERY BRITTLE
-POOR CONDUCTORS
NONMETAL FAMILIES
1. Hydrogen
-1 electron, 1 proton, 0 neutrons
-HIGHLY REACTIVE (the Hindenburg??)
-Very LIGHT
-FLAMMABLE
-Makes up 90% of all atoms in the universe
NONMETAL FAMILIES
2. Halogens (Group 7A or 17)
-7 valence electrons
-HIGHLY REACTIVE (want to steal 1 electron to be
full/stable)
-Salt Formers (ex. NaCl)
-MOST REACTIVE NONMETALS
NONMETAL FAMILIES
3. Noble Gases (Group 8A or 18)
-Complete outer shell
-Helium has 2 on the 1st shell = full
-The rest all have 8 = full
-DO NOT FORM COMPOUNDS
(b/c they’re stable)
MIXED GROUPS:
METALS, NONMETALS, METALLOIDS
GROUPS 13-16 (3A-6A)
1. Boron Group (Group 3A or 13)
-3 valence electrons
-A few are SEMICONDUCTORS
MIXED GROUPS:
METALS, NONMETALS, METALLOIDS
GROUPS 13-16 (3A-6A)
2. Carbon Group (Group 4A or 14)
-4 valence electrons
-Carbon = nonmetal
-Silicon/Germanium = metalloids
-Tin/Lead = metals
MIXED GROUPS:
METALS, NONMETALS, METALLOIDS
GROUPS 13-16 (3A-6A)
3. Nitrogen Group (Group 5A or 15)
-5 valence electrons
-Nitrogen = 78% of our atmosphere
-N/P/As = nonmetals
-Sb = metalloid
-Bi = metal
MIXED GROUPS:
METALS, NONMETALS, METALLOIDS
GROUPS 13-16 (3A-6A)
4. Oxygen Group (Group 6A or 16)
-6 valence electrons
-Oxygen = 21% of our atmosphere
-O/S/Se = nonmetals
-Te/Po = metalloids
ISOTOPES
Isotope = Atoms of the same element that have
different numbers of neutrons
ex: Carbon-12 = nonradioactive (6 P and 6 N)
Carbon-14 = radioactive (6 P and 8 N)
Atomic Mass v/s Average Atomic Mass
- Atomic mass = protons + neutrons in a single
atom
- Average Atomic mass = average mass of the
mixture of an element’s isotopes