Chemical Bonds of Compounds
Conduction of Heat & Electricity
Review of Periodic Table
Compounds
with Ionic Bonds
-One or more
electrons are
transferred from
the atom(s) of the
metal to the
atom(s) of the nonmetal.
-When the electron(s)
are transferred, the
result is a positive
and a negative
species called ions
Ions
• Are similar to atoms except that the
number of protons does not equal the
number of electrons
• They have a net electric charge
• When these species come in contact they
stick together
• They dissolve in water which allows these
solutions to conduct electricity
Characteristics of Ionic Compounds
• When these compounds
are dissolved in water, the
ions separate back into
their individually charged
species (dissociation)
• This separation allows
these solutions to conduct
electricity.
• An ionic compound in
solution is called and
electrolytic solution (a
solution capable of
carrying an electric
current)
Compounds with Covalent
Bonds
- made up of non-metals
- electrons are shared
- bond is a permanent
attachment between the
atoms to form a unit
- a chemical reaction must
occur to separate these
atoms back to their
elemental form
-they do not separate into
charged species when
dissolved in water, do not
conduct electricity
Review Kinds of Bonds
Molecule = an electrically neutral group of atoms held together
strongly enough to act as a single particle.
Conductivity of Electricity by Metals
• When more electrons are pushed into a piece of metal
(by an electric current for example) the electrons just
flow through the metal in between the metal atoms
• Common metals - copper, silver, aluminum.
Conductivity of Heat by Metals
Ability of Metal to Conduct Heat
• One of the properties that defines an
element as a metal is its ability to conduct
heat and electricity
• The reason metals conduct heat so well is
that the electrons in them can move
around easily, and they can carry heat
from one part to another
More Specifically
Heat Conduction is:
• The flow of heat from a hot part of a body to
a cooler part, without transfer of matter.
• Conduction can also take place from one
body to another, provided the two bodies
are in contact, and a temperature difference
exists between them.
For example, a pot on a hot
plate is heated by conduction
from the stove surface, via the
underside of the pot.
How is the heat conducted?
• Through its particles that are constantly
vibrating or oscillating against each other.
• Through these collisions, the heat energy
is conducted through the length of the
piece of metal.
• The hotter atoms (faster moving) vibrate
against slower moving cooler atoms
causing them to heat up.
Ability of a metal to conduct heat?
• What is an element of
metal made of?
Atoms that vibrate
Free electrons that
move around
Do all metals have the same ability to
conduct heat?
• In some metals (copper, gold, silver, aluminum) the
electrons can travel past hundreds of atoms before
bumping into something that makes them change
directions.
• In others (especially alloys with more than one type
of metal atom) the electrons travel only past a few
atoms before bouncing off some irregularity in the
material.
• Alloys are basically a mixture of two or more metals
- Depending on what element is added, you could
create Stainless Steel or Galvanized Steel or carbonsteel alloys are used in armor plating and weapons.
Comparison of Heat Conduction
Capability
Percent of Heat Conduction Capacity – Silver = 100%