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Chapter 6 and 7
The Periodic Table
and Periodic Law Harry Potter Sings the Element
Song
Jim Lehrer The Real Periodic
Table Song
1789 - Lavoisier
Acid making
phosphorous
sulfur
carbon
Gas like
light
heat
oxygen
Azote (nitrogen)
hydrogen
1789 - Lavoisier
Metallic
Copper, nickel, iron
Cobalt, mercury, tin
Gold, lead, silver, zinc
Earthy
Lime (calcium hydroxide)
Magnesia (magnesium oxide)
Manganese, tungsten
(platina) platinum
Barytes (barium sulphate)
Argilla (Aluminum oxide)
Silex (silicon dioxide)
I. Development of the Modern
Periodic Table 6.1 pg. 151-158
1. Compiled a list of 23 elements known
at the time.
2. 1800’s: changes in the world
3. Electricity used to break compounds,
spectrometer, industrial revolution
4. Tripled Lavoisier’s number of elements
5. 1860 chemists agreed on atomic masses
A. Lavoisier – 1790’s
B. John Newland - 1864 1. Proposed an organization scheme
2. Arranged by increasing atomic mass
3. The elements’ properties repeated
every eighth element
4. The law of octaves.
Musical Analogy
C. Meyer, Mendeleev, & Moseley
1. Meyer & Mendeleev each demonstrated connections between atomic mass and elemental properties.
2. Mendeleev published first and showed the connections’ usefulness
3. Mendeleev predicted the existence and properties of undiscovered elements.
4. He left blanks for undiscovered elements
Can you find the errors in his system?
"...if all the elements be arranged in order of their atomic
weights a periodic repetition of properties is obtained." -
Mendeleev
Mendeleev’s First Periodic Table
5. Henry Moseley (1913):
British chemist - discoveries resulted in a
more accurate positioning of elements
by determination of atomic numbers.
(Tragically for the development of
science, Moseley was killed in action at
Gallipoli in 1915).
5. Moseley (continued)
5. When atoms were arranged according to
increasing atomic number, the few problems
with Mendeleev's periodic table had
disappeared. Because of Moseley's work, the
modern periodic table is based on the atomic
numbers of the elements
6. Periodic Law: There is a periodic repetition of
the chemical and physical properties of the
elements when they are arranged by increasing
atomic number.
BCC History of the
Periodic Table
A. Columns on the periodic table are
called groups or families.
Atomic number increases as you
move down on the periodic table.
Each group is numbered one though
eight, followed by the letter A or B.
II. The Modern Periodic Table
What group is Chlorine in? VIIA
B. The rows on the periodic table are called periods.
Each row on periodic table (except the first) begins with a metal and ends with a noble gas.
Beginning with hydrogen in period 1 there are a total of seven periods. In between, the properties of the elements change in an orderly progression from left to right.
The pattern in properties repeats after group VIIIA (18).
II. The Modern Periodic Table
C. Why does the first period on the periodic table only have two elements?
Only two electrons can occupy the first energy level in an atom.
The third electron in lithium must be at a higher energy level.
Lithium is the first element in Group IA and in Period 2.
II. The Modern Periodic Table
D. The groups designated with an A (IA through VIIIA) are often referred to as the main group or representative elements because they possess a wide range of chemical and physical properties.
The groups designated with a B (IB through VIIIB) are referred to as the transition elements.
II. The Modern Periodic Table
III. Classification of the Elements
A.Valence Electrons
1. electrons in the highest principal
energy level
2. What would group IA look like?
3. Atoms in the same group have
similar chemical properties because
they have the same number of
valence electrons.
B. The s-, p-, d- and f- block elements
1s1, 2s1….
A. Metals are elements that have luster, conduct heat and electricity, and usually bend without breaking, and are solid at room temperature. With the exception of tin, lead, and bismuth, metals have one, two, or three valence electrons.
III. Classification of the Elements
Metals are to the left of the heavy stair-step line that zigzags down from Boron (B, in column IIIA) to astatine (At) at the bottom of group VIIA (hydrogen is the exception). Alkali metals – group IA, the most reactive of all metals. They react with water to form alkaline solutions.
III. Classification of the Elements
Alkaline earth metals group IIA. These elements form compounds with oxygen, called oxides. All transition elements are metals.
III. Classification of the Elements
Inner transition metals are know as lanthanide and actinide series and are located along the bottom of the periodic table. Because of their natural abundance on Earth is less than 0.01 percent, the lanthanides are sometimes called the rare earth elements. All of the lanthanides have similar properties.
III. Classification of the Elements
All of the actinides are radioactive, and none beyond uranium (92) occur in nature.
III. Classification of the Elements
B. Nonmetals are elements that are generally gases or brittle, dull-looking solids. They are poor conductors of heat and electricity.
The only liquid nonmetal at room temperature is bromine (Br).
The highly reactive group VIIA is the halogens, “salt formers.” The extremely un-reactive group is the noble gases.
The nonmetals oxygen and nitrogen make up 99 percent of Earth’s atmosphere.
III. Classification of the Elements
Carbon, another nonmetal, is found in more compounds than all the other elements combined.
Their melting points tend to be lower than those of metals.
III. Classification of the Elements
C. Metalloids or semimetals.
Metalloids are elements with
physical and chemical properties
of both metals and nonmetals.
Silicon and germanium are tow of
the most important metalloids as
they are used extensively in
computer chips and solar cells.
III. Classification of the Elements
Some metalloids such as silicon,
germanium (Ge), and arsenic
(As) are semiconductors.
III. Classification of the Elements
A semiconductor is an element that
does not conduct electricity as well
as a metal, but does conduct slightly
better than a nonmetal.
The ability of a semiconductor to
conduct an electrical current can be
increased by adding a small amount
of certain other elements.
III. Classification of the Elements
Silicon’s semi conducting properties made the computer revolution possible.
III. Classification of the Elements
Your television,
computer, handheld
electronic games, and
calculator are electrical
devices that depend on
silicon semiconductors.
All have miniature electrical circuits that use silicon’s properties as a semiconductor.
You learned that metals generally are good conductors of electricity, nonmetals are poor conductors, and semiconductors fall in between the two extremes.
III. Classification of the Elements
The ability of a semiconductor to conduct an electrical current can be increased by adding a small amount of certain other elements.
Silicon’s semi conducting properties made the computer revolution possible.
Your television, computer, handheld electronic games, and calculator are electrical devices that depend on silicon semiconductors.
III. Classification of the Elements
What clues does the arrangement of the football players on the
field give about the functions of their positions?
V. Periodic Trends 6.3 pgs. 163-169
A. Atomic Size or Radius
1. How closely an atom lies to a neighboring atom.
2. Metals – half the distance between two adjacent atoms in a crystal
3. Nonmetal – determined from a diatomic molecule of an element
Time out! What’s a diatomic
element?
Mr. Brinklehoff
BrINClHOF
gases
N2, H2, F2…
an element that when not
chemically bonded with any other
elements, will form a molecule
having two atoms of the element.
A. Atomic Radii - trend (cont.)
Size increases going across – right to left. (Across same energy level, but add protons and the ‘pull’ of nucleus is greater and pulls electrons closer.)
Size increases going down a group. Electrons are at progressively higher levels, and shielding effect is increasing.
A. Atomic Radii (continued) Shielding Effect – lots of inner electrons
shield or protect the outer electrons from the ‘pull’ of the positive nucleus.
What happens to shielding effect as
you go down the periodic table? increases
What happens to shielding effect as
you go across the periodic table?
Stays the same
B. Ionic Radius
Positive ions are always smaller than
neutral atoms
+1 +2 +3
-1 -2 -3
Negative ions are always larger than
neutral atoms because their nuclear
attraction is less
Going down a group – both anions and
cations get bigger
Going across: + decrease, - increase
Smaller Larger
C. Ionization Energy
Energy required to remove an
electron from a gaseous atom.
Think of ionization energy as an
indication of how strongly an atom’s
nucleus holds onto its valence
electrons.
Bigger your ionization energy the
harder it is to rip an electron away.
How easy is it to become an ion?
I.E. increases going up (harder to pull off outer
electrons when atoms are smaller)
I.E. increases going across (harder to pull off
electrons because of nuclear attraction is
hanging onto them.
Metals have lower I.E., nonmetals have high I.E.
High High
D. Electronegativity
indicates the relative ability of an
atom to attract electrons in a
chemical bond “hogs electrons”
The bigger the electronegativity
the bigger the ‘hog’
Polar Covalent Bonds
Though atoms often form
compounds by sharing
electrons, the electrons
are not always shared
equally.
• Fluorine pulls harder on the electrons it
shares with hydrogen than hydrogen does.
• Therefore, the fluorine end of the molecule
has more electron density than the hydrogen
end.
Electronegativity Electronegativity is the
ability of atoms in a
molecule to attract
electrons to themselves.
On the periodic chart,
electronegativity increases
as you go…
…from left to right across a
row.
…from the bottom to the
top of a column.
D. Electronegativity (continued)
moving across, electronegativity increases
moving up electronegativity increases
high highest
E. Electron Affinity
“Electron Grabbiness” or how easy it is
for an atom to gain electrons (make a
negative ion = anion)
(-) negative = energy released
(+) positive = energy absorbed
E. Electron Affinity (continued)
Generally decreases going down a group
because atomic size increases
Increases going across because atoms are
smaller and nucleus charge increases
F. Melting Points metallic side – decreases as you go down
non-metals- increase going down
melting pt of gases are very low (-100 C)
H. Chemical Activity
metals – increase going down, most active? Cs
non metals – decreases going down, most active?
F