Chp. 16
I.
The Periodic Table
Organizing the Elementsa. Each row in the table is called a period.
i. Periods indicate how many shells are present in that atom
ii. Shell- region of space where electrons are (picture pg. 391)
1. Noble gas shell modela. Accounts for the behavior observed of elements.
b. each shell holds a given number of electrons
c. As we move away from the nucleus electrons in each shell increases.
i. Shell 1 –2 electrons
ii. Shell 2 –8 eiii. Shell 3 –8 eiv. Shell 4 –18 ev. Shell 5 –18 e-…
b. Valence Electronsi. Electrons in the outer shell of the atom
ii. First to react with the environment
iii. Most significant electrons
c. Electron affinity- (Electronegativity)
i. Ability of an atom to attract electrons from other atoms
ii. Increases in a direction to the upper right
d. Each column in the table is called a group.
i. Groups all have similar chemical and physical properties
ii. Special Groups of Elements
a. Metals- generally shiny, good conductors of electricity and heat
i. Malleable- hammered into shapes or bent without breaking.
ii. Ductile- drawn into wires easily
iii. Most are solid at room temperature
iv. Four types of metals
1. Alkali metals
a. Used in soaps
b. Group 1 in the periodic table
2. Alkali Earth metalsa. Group 2
b. Resistant to fire
3. Transition Metals
a. groups 3-12
b. used for structural purposes
4. Inner Transition Metals -periods 6 and 7, atomic numbers
58-71 and 90-103
a. hard to purify- they all have similar properties
i. a problem nuclear power because we need
pure samples of Uranium and Plutonium for
power
b. used in computer monitors
b. Non metals- poor conductors of electricity and heat
i. Some are transparent
ii. Not malleable or ductile
iii. Brittle and shatter when hammered
iv. Two types of non-metals
1. Halogens
a. “salt forming” in Swedish
b. group 17
2. Noble Gases
a. unreactive gases
b. Nobles do not react with common folk
c. Metalloids
i. Metallic and nonmetallic in characteristics
ii. Poor conductors of electricity – used in semiconductors and
circuits as insulators
II.
Periodic Trendsa. Atomic Radius- distance from the nucleus to the atoms outer surface.
i. Increasing atomic number leads to decreasing atomic radii
Figure 1-
(Increases in a direction to the lower left)
ii. This happens because of increased nuclear charges pull electrons closer to the nucleus.
b. Ionization Energy- the amount of energy required to pull an electron away from an atom
i. Forms a positively charged atom called an ion.
ii. Generally increases with increasing atomic number.
Figure 2-
(Increases in a direction to the upper right)