3. Periodicity Flashcards
How are elements arranged in the Periodic Table?
Elements are arranged by increasing atomic number and by changes in physical and chemical properties.
Group vs. Period
The group is the number of valance electrons (vertical)
The period is the number of shells (horizontal)
What are the different categories of elements in the Periodic Table? and where on the Periodic Table are they?
Alkali metals (group 1)
Alkaline earth metals (group 2)
Transition metals (group 3 - 12)
Halogens (group 17)
Noble gases (group 18)
Lanthanois (La to Lu)
Actinoids (Ac to Lr)
Non-metals
all on the right side of the periodic table (except H)
Non-metal physical properties
Mostly gaseous at room temperature
Dull
Brittle m
Poor electrical conductivity
Low densities
High ionization energies
High electronegativity
Non-metals chemical properties
Gain electrons to form anions
Oxidizing agents (therefore reduced themselves)
form covalent bonds with nonmetals
form acidic oxides
Metals
Found on the left side of the Periodic Table
Metals physical properties
Solid at room temperature (except mercury)
Metallic luster (shiny)
Malleable and ductile
High electrical conductivity
High density
Low ionization energy
Low electronegativity
Metals chemical properties
Loses electrons to form cations
Reducing agents (therefore oxidized themselves)
Form ionic bonds with nonmetals
Form basic oxides
What is electron shielding?
occurs when inner shell electrons shield valance electrons from full attraction to nucleus
What is the trend of electron shielding?
Constant across the period
Increases down a group (main level occupied increases)
What is the effective nuclear charge?
The net positive charge experienced by valance electrons
ENC = Atomic number - # of Shielding electrons
What is the trend for effective nuclear charge?
Increases across period (higher atomic number)
Constant down the group
What is ionization energy?
The minimum amount of energy required to remove a mole of electrons from a mole of gaseous atoms of a particular element.
Al(g) –> Al+(g) + e-
What is the trend for ionization energy?
Increases across period (increase in nuclear charge causes increased attraction between outer electron and nucleus, more difficult to remove)
Decreases down the group (electron being removed is from the furthest energy level from nucleus, easier to remove valance electrons as atomic radius increases down a group)
What is 1st ionization energy?
Energy required to remove one mole of electrons from one mole of gaseous atoms to produce one mole of gaseous 1+ ions (kj mol-1)