Transcript Intro to the Periodic Table

Organizing the Elements
Metals
Nonmetals and Metalloids
Matter is composed of
Elements…
There are over 100
different elements
with a wide variety
of properties.
Some form
compounds easily,
while others do
not.
Mendeleev, the dirty
detective…
-Observed the mass,
reactivity, and general
properties of various
elements.
- Noticed patterns
among the elements and
began sorting them in
order of increasing
atomic mass.
Chlorine
Group 17
Nonmetals…
1. All poisonous
as gases
Bromine
2. All react easily
to form salts
Lithium
Group one metals…
Sodium
1. All are soft
gray metals
2. All very
reactive
Potassium
3. All form salts
In 1869, Mendeleev
Published the first
Periodic Table based on
his findings…leaving
blank spaces for elements
that haven’t been
discovered yet!!!
Inside an atom
An atom is the smallest unit of matter
that still retains the properties of a
particular element.
Atoms and the P.T.
An “atomic mass unit” or AMU is
equivalent to the mass of one
proton/neutron.
Since electrons have virtually no
mass, the “atomic mass” of an
element refers to the number of
protons and neutrons in found in its
nucleus….
Atoms and the P.T.
(cont…)
However…atoms of various elements
sometimes have different number of
neutrons in their nuclei, so in actuality,
atomic mass refers to the average mass
of one atom of a particular element.
Atoms and the P.T.
(cont…)
For example….99%
of all the helium
atoms in the world
have 2 neutrons.
However, 3 out of
every 1,000 have 3
neutrons instead of
2. Therefore, on the
P.T. helium has an
atomic mass of
4.003 AMU’s
Atoms and the P.T.
(cont…)
“Atomic Number”
refers to the number
of protons in an
atom’s nucleus
Elements are
arranged on the P.T.
according to atomic
number.
***Atomic number
(# of protons) is a unique
property***
Organization of the
Periodic Table
An element’s properties can
be predicted by its location
on the Periodic Table…
The P.T. is divided into 18
individually numbered
columns called “families.”
(also known as a “group”)
Organization of the
Periodic Table (Cont…)
Every element in the same family has
similar properties.
Group 1 metals all react violently with
water…
Group 18 non-metals are inert, in other
words, they don’t react with anything.
Organization of the
Periodic Table (Cont…)
A horizontal row across the P.T. is called a
“period.”
The elements in a row do not have similar
properties…
As you move across a period, the elements
gradually change properties.
Why the table works…
An element’s ability to
bond with an atom of
another element its called
its “bonding power”
Bonding power, is
determined by the
outermost electrons
surrounding an atom…the
“valence electrons.”
Metals…What is a
Metal?
Metals are found to the left of the zigzag
line on the P.T.
They are classified based on their
physical properties: hardness, shininess,
malleability, and ductility.
Metals: Physical
Properties
Malleability- The
ability of a metal
to be pounded into
shapes
A “ductile”
material is one
that can be pulled
out or “drawn”
into a long wire.
Metals: the Chemical
Properties
The ease and speed in which an
element reacts with other elements is
called its “reactivity.”
Metals show a wide range of chemical
properties, or reactivity.
For example……
Metals: the chemical
properties
Iron will react
with oxygen in
the air to form
iron oxide (rust).
Gold and
chromium are
unreactive.
Metals: the Physical
properties
Shininess
•Magnetism
•Hardness
•Conductivity
Alloys
An “alloy” is a mixture of metals…alloys
combine the beneficial attributes of 2 or
more metals from the P.T.
For example….
Alloys (cont…)
Iron rusts easily, but when mixed with
vanadium and chromium, it forms
stainless steel.
Alloys (cont…)
Copper is soft and malleable, but when
mixed with tin, it forms bronze…an
attractive and durable alloy.
Metal families:
the alkali metals
The group 1 metals are
also known as the alkali
metals.
They are so reactive that
they are never found
uncombined in nature.
They are so soft, you could
easily cut them with a knife.
Metal families:
the alkaline earth metals
Group 2 metals are also
very reactive, but not as
much as group 1.
They are also not found
uncombined in nature.
They are white, hard,
and good conductors of
electricity.
Metal families:
the transition metals
These metals form a bridge
between the reactive metals on
the left side of the P.T., and the
less reactive metals and other
elements on the right side of
the P.T.
They become less and less
reactive as you move from left
to right on the P.T.
Lanthanides and Actinides
Also known as the “rare
earth elements,”
Lanthanides and Actinides
are rare, soft, malleable
metals.
Some actinides are highly
radioactive (they have
unstable nuclei)
Metalloids
On the border between the metals and
the non-metals are the “metalloids.”
Metalloids have some properties of
metals and some properties of nonmetals.
As “semiconductors” they’re varying
ability to conduct electricity makes them
useful in industry
Metalloids
Metalloids
The Nonmetals…
All 17 nonmetals are extremely
important to living things.
They are all found (except for
hydrogen) to the right of the zigzag
line on the P.T.
Most are gases, some are crumbly
solids, and Bromine is the only liquid.
The Nonmetals…
Chemical properties of
nonmetals
Most all nonmetals
react easily to form
compounds.
When metals and
nonmetals combine,
metal elements
transfer their valence
electrons to the
nonmetal.
Chemical properties of
nonmetals (cont…)
When nonmetals
combine to form
compounds with
other nonmetals,
valence electrons
are shared between
two atoms.
Diatomic chlorine (Cl2)
Chemical properties of
nonmetals (cont…)
A molecule that
contains only 2
atoms (usually the
same element) is
called a “diatomic
molecule.”
Families of nonmetals:
The carbon family
In this family,
carbon is the only
nonmetal. All living
things contain
compounds
composed of long
chains of carbon
atoms.
Families of nonmetals:
The Oxygen Family
- The Oxygen we
breathe is
essential in
allowing our
bodies to function.
-Oxygen and sulfur
form compounds
very easily.
Families of nonmetals:
The Halogens
Group 17 elements
are known as the
halogens, and are
very reactive.
They are dangerous
to humans, but form
compounds that are
very useful.
Families of nonmetals:
The Noble Gases
These gases have a full valence shell (8
electrons), and do not react at all with
any other elements.
They are found in small amounts in the
atmosphere and glow brightly when
electricity passes through them.
Group 18 non-metals are inert, in other
words, they don’t react with anything.
Hydrogen:
the simplest element
One hydrogen atom
contains only one proton
and one electron.
90% of the atoms in the
universe are hydrogen.
When an electric current
passes through water,
chemical bonds are broken
and diatomic hydrogen gas
(H2) is formed.
“That’s All Folks!”
More to come…