Download Goal 4.01

Goal 5.02
Atomic Structure
Protons, Neutrons, Electrons
Name
Symbol Location Charge
Mass
Proton
p+
Nucleus
+1
1amu
Neutron
n
Nucleus
0
1amu
Electron
e-
Cloud
-1
1/2000amu
Atomic Number
Atomic number is the number of protons in
an element.
Atoms of the same element always have
the same number of protons.
Atomic numbers are found on periodic
table beside element’s symbol.
Mass Number
Mass number is the number of protons
plus the number of neutrons in an
element.
Unless specified, the number of p’s and
n’s are equal and the mass number is
twice that of the atomic number.
Atom Notation
A symbol is the abbreviation for an
element’s name. They can be found on the
periodic table.
The typical notation for an atom includes
the element’s symbol with atomic number
in subscript to the left and mass number in
superscript to the left.
Isotope
An isotope is an atom with a differing
number of neutrons and therefore a
different mass number.
It can be written in normal notation or
isotope notation.
Isotope notation is the element’s symbol
followed by a dash and the atomic mass.
Atomic Mass
The atomic mass of an element is the
average of all the naturally existing
isotopes of an element.
It can be found on the periodic table under
the element’s symbol.
Ion
An ion is an atom with a differing number
of electrons and therefore an overall
charge.
The notation includes the charge written in
superscript to the right of the element’s
symbol.
The charge can be determined by
canceling protons and electrons to see
what remains.
Determining p,n,e
Given the notation of an element you should be
able to determine the number of p, n, and e.
The first step is to find the element on the
periodic table and determine its atomic number
which gives you the number of p.
The number of p’s will never change.
From there you must determine the number of n
and e.
These may be different from the number of p
and can be found by looking at notation of the
element.
Orbits
Electrons orbit the nucleus in distinct
levels called orbits. At ground state an
orbits can hold….
The 1st orbit can hold 2 electrons.
The 2nd can hold 8 electrons.
The 3rd can hold 18 electrons.
The 4th can hold 32 electrons.
Drawing Atomic Structure
The arrangement of electrons within their orbits can be
shown using electron dot diagrams.
Start by drawing a nucleus containing the correct
number of protons and neutrons.
Then determine the number of electrons within the atom.
Draw the 1st orbit and fill that orbit with electrons.
Electrons are drawn on the orbit line as a solid circle.
Continuing drawing and filling orbits until the correct
number of electrons is reached.
Valence Electrons
The electrons in the very outer orbit are
called valence electrons.
Valence electron diagrams are drawn by
using dots that represent the valence
electrons around the element’s symbol.
Each side of the symbol can contain two
dots.