Periodic Characteristics
 Valence electrons determine chemical & physical properties of
the elements
 Valence electrons – the electrons in the outermost energy level
 Elements with the same number of valence electrons will have
similar chemical properties.
 Metals have shared properties because they lose electrons
 Nonmetals have shared properties because they gain electrons
Periodic Characteristics
 Ion – an atom that either loses or gains electrons
 Metals tend to lose their valence electrons.
 Losing electrons(negative charges) makes
them positive
Ca +ion
 Cation – a positive ion
 Nonmetals tend to gain electrons
 Gaining electrons makes them negative
 Anion – a negative ion
a negative ion
 The number of valence electrons determine the physical
and chemical properties of the groups
Periodic Table Groups
Group 1: Alkali Metals
• Only 1 valence electron
• The most reactive metals
• Not found in nature in pure
form.
• Always in compounds
• Most reactive: Francium
Videos: alkali metals in water
1
Periodic Table Groups
 Group 2: Alkaline Earth Metals
• Has 2 valence electrons
2
• Still very reactive, but not as
reactive as Group 1.
• Not found in nature in pure
form. Always in compounds
demo: magnesium & oxygen
Periodic Table Groups
 Groups 3 through 12: Transition
Metals
• Valence electrons vary
• metals can form multiple
cations
• Ex. Cr2+,Cr3+,Cr7+
• compounds are brightly colored
• Group 11 & 12 are least
reactive
demo: colored compounds
3 4 5 6 7 8 9 10 11 12
Periodic Table Groups
 Group 14: The Carbon Group
(aka Crystallogens)
• Have 4 valence electrons
• Carbon has three allotropes:
coal, diamond, graphite
• Allotrope: substances made
from the same element, but
with different physical and
chemical properties
Group 15: Nitrogen Group(aka Pnictogens)
• Has five valence electrons
*note- bottom element is a metal!*
1415
Periodic Table Groups
 Group 16: Oxygen Group
(aka Chalcogens)
 6 valence electrons
 oxygen has 2 allotropes:
 O2 (air) & O3(ozone)
 Group 17: The Halogens
 “salt-forming”
 7 valence electrons
 most reactive nonmetals
 Most are diatomic(2 atoms):
diatomic - compounds made
with two atoms of the same
element.
- Other diatomic elements: Hydrogen, Oxygen & Nitrogen.
- Together, they form BrINClHOF: Bromine(Br2) Iodine(I2),
Nitrogen(N2), Chlorine(Cl2), Hydrogen(H2), Oxygen(O2), and
Fluorine(F )
1617
Periodic Table Groups
 Group 18: The Noble
Gases
• 8 valence electrons(except
helium which has 2)
• full outer shell (aka filled
principal energy level)
• chemically unreactive
Lanthanides →
actinides →
Lanthanides
 contain the rare earth metals
 Many used in modern electronics
 Actinides
 some are man-made
 all are radioactive & decay over time
18
Electron Configuration &
The Periodic Table
Think back to electron configuration• Electrons are arranged in energy levels
• Energy levels are made up of orbitals: s, p, d & f
• s can hold 2 electrons, p can hold 6, d holds 10, f holds
14
• Electron configuration can be predicted by the location of
the element on the Periodic Table.
P.T. & Electron Configuration
The Periodic Table is sorted by the location of valence
electrons in the electron configuration
•
•
•
•
s-block - Electron configuration ends with s¹ or s²
p-block - Electron configuration ends with p1 through p6
d-block - electron configuration ends with d1 through d10
• Atoms in the d-block often form multiple cations
f-block: electron configuration ends with f1 to f14
Blocks
s-block
dblock
f-block
pblock