Download ATOMS and PERIODIC TABLE - John Q. Adams Middle School

ATOMS
and
PERIODIC TABLE
Pg. 54
The Structure of Atoms
Atomic
Theory – states that all matter
is made up of tiny particles called atoms.
Matter is defined as anything that has
mass and takes up space.
Pg. 54
The Structure of Atoms
 Atoms
are made up of three subatomic particles:
 Protons – positive charge
 Neutrons – no charge; neutral
 Electrons – negative charge
Protons,
quarks.
 Protons
Neutrons, and Electrons are made up of particles called
and Neutrons are located in the nucleus of an
atom
 Electrons are located outside the nucleus in random
patterns, but clustered in electron shells.
Pg. 54
The Structure of Atoms
Electron
The
Shells
first electron shell has no more than two
electrons.
The Second shell can have as many as eight
electrons.
The other shells have varying numbers of electrons
depending on the number of electrons in the atom.
The last electron shell usually will hold no more than
eight electrons.
Pg. 56
Properties of Elements In the
Periodic Table
The
number of protons in an atom gives the
atom its identity.
Atoms that have the same number of protons
are called elements.
Elements are arranged according to their
atomic number on the periodic table.
The
atomic number corresponds to the number of
protons or electrons in the atom.
Pg. 56
Properties of Elements in the
Periodic Table
The
atomic mass is the number of
protons plus the number of neutrons
found in the atom.
Electrons
do not contribute to the mass of
the atom because they are so small.
Protons
+ Neutrons = Atomic Mass
Pg. 56
Properties of Elements in the
Periodic Table
 Atoms
of the same element do not always have the
same number of neutrons.
 Atoms that have different numbers of neutrons are
called isotopes.
 The atomic mass given on the periodic table is the
average of all the isotopes and is not a whole number.
 To find the number of neutrons for an element,
subtract the number of protons (atomic number) from
the atomic mass.
 Atomic
Mass – Atomic Number = Number of Neutrons
Pg. 56
Properties of Elements in the
Periodic Table
The
periodic table is made up of elements
placed in organized rows and columns according
to properties and size.
Rows are called period and are arranged
according to the atomic numbers.
Columns are called families and have similar
properties and always have the same number of
electrons in their outer shell.
You
can remember that families of people have
similar characteristics or properties and a family
tree goes down.
Pg. 57
Properties of Elements in the
Periodic Table
Elements
can all be classified as metals,
nonmetals, metalloids, or noble gases.
Metals:
Make
up the majority of the table and are located
to the left.
Hydrogen
Are
is the only exception.
solids at room temperature, are hard, have
luster (shiny), and conduct heat and electricity.
Pg. 57
Properties of Elements in the
Period Table
Nonmetals:
Right
side of the periodic table.
Usually gases or dull, brittle solids at room
temperature.
Metalloids:
Elements
diagonally between the metals and
nonmetals.
Have properties of both metals and nonmetals.
Used in semiconductors and computer chips.
Pg. 57
Properties of Elements in the
Periodic Table
Noble
Gases:
Located
in one family; Family VIIIA
Far right column of the periodic table
Nonmetal gases that do not react with any
other elements.
Pg. 61
Reactivity of Elements in the
Periodic Table
An
element is most stable when its last
electron shell is full.
All elements have outer shells that can
hold 8 electrons.
Exception:
Hydrogen and Helium
Pg. 61
Family VIIIA
Noble
gases have 8 electrons in their
outer shells
Exception:
2 electrons.
Very
Helium, but is complete with only
stable elements
Will not react with other elements
Pg. 61
Family IA
Alkali
Metals
Exception
Very
is Hydrogen (non metal)
reactive
Have only one electron in the outer shell
Give up its one electron forming ions
Pg. 61
Family IIA
Alkaline
Have
Earth Metals
2 electrons out of 8 possible in their
outer shell
Very
reactive, but less reactive than the
Alkali Metals
Pg. 62
Family B
Transition
Metals found in the middle of
the periodic table.
Reactivity of these metals increases as
you go down the periodic table and from
right to left.
Pg. 62
Family VIIA
Halogens
Most
reactive nonmetals
Have 7 out of 8 possible electrons in
their outer shell
Combine with metals to form a salt
Example:
Na + Cl → NaCl
Pg. 62
Family VIA
No
common name
Have 6 of 8 possible electrons in their
outer shell
Not as reactive as the halogens
Pg. 62
Family IIIA through VA
No
common name
Family IVA is half full making it more
stable than IIIA or VA on either side of
it.
Pg. 64
Bonding of Atoms
Atoms
of different elements combine
chemically to form compounds
Done
by sharing or transferring electrons
Electrons
in the outer shell of an atom
are called valence electrons
Ionic bonds result in the transfer of
electrons from atom to atom.
Pg. 64-65
Bonding of Atoms
Ionic
bonds are usually present in
compounds which have metal atoms
bonded with nonmetal atoms
Covalent bonds are when two or more
atoms share electrons
Usually present with two or more
nonmetals
Pg. 69
Radioactivity
Atoms
of the same element can have different
numbers of neutrons.
Atoms of the same element that have
different numbers of neutrons are called
isotopes
When there are too many neutrons in the
nucleus the nucleus becomes unstable.
An unstable isotope will be radioactive and is
called a radioactive isotope
Pg. 69
Radioactivity
Radioactive
particles:
Alpha
2n
atoms give off three
Particles – helium nucleus with 2p and
When
an alpha particle is given off the atomic
number of the parent nucleus is reduced by two
If ingested will do more damage to internal
tissues than other forms of radiation.
Pg. 70
Radioactivity
Beta
Particles – electrons emitted
Penetrate
more than alpha particles but can be
stopped by lead
Gamma
Can
All
Particles – high energy x-rays
only be stopped by thick lead or concrete
elements with atomic numbers
greater than 83 are radioactive
Pg. 70
Radioactivity
A
radioactive atom that emits an alpha, beta,
or gamma particles is going through a process
called radioactive decay
Radioactive decay causes an atom of one
element to become a different element by
reducing its atomic number
The half-life of a radioactive atom is the time
it takes for ½ of the particles in the nucleus to
decay
Pg. 71
Fission
Fission
occurs when the nucleus of an atom
that is so unstable that it splits into two
smaller atoms.
Releases
a large amount of energy
Used in nuclear reactors
Reactors use control rods to absorb excess energy
Nuclear bombs have no control rods and release all
of the energy in one blast
Pg. 72
Fusion
Fusion
is when two small atoms are
joined together to form a larger atom
Produces energy also
Requires high temperatures
Occurs in the sun when two hydrogen
atoms
fuse to form a helium atom
Scientists are still working to recreate this
but can’t generate the high temp
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