Elements and the
Periodic Table
By Carl Fusco
The Periodic Table
• Designed by Mendeleev in 1869
• Organizes matter based on its
properties and atomic number
• Allowed for the prediction of then
unknown elements
Periods and Families
• The rows in the periodic table are known as
periods.
• The columns in the periodic table are known as
groups.
• Groups tend to have similar properties.
• Major groups (multiple columns):
– Metals
– Non metals
– Metalloids
• Single column groups:
–
–
–
–
Alkali metals
Alkali earth metals
Halogens
Noble gases
Modern View of the Atom
• Protons, neutrons, electrons
Subatomic
Charge
Particle
Symbol
Mass
Electron
1-
e-
1/2000
Proton
1+
p+
1
Neutron
0
n0
1
The Bohr-Rutherford Model
Helium Atom
• 2 positive protons in
nucleus
• 2 neutral neutrons in
nucleus
• 2 negatively charged
electrons in the first
energy level
– 2-8-8-2 are the
number of electrons
in each energy level
for the first 20
elements
Standard Atomic Notation
(for a neutral atom)
Atomic symbol
Mass number
80
35
Atomic number
Br
Number of
protons
Atomic
number (35)
35 p+
Number of
electrons (for
neutral atom)
Atomic
number (35)
35 e-
Number of
neutrons
Mass number
– Atomic
number
(80-35=45)
45 n0
Neutral Atoms and Ions
• When using standard atomic
notation you can assume the atom is
neutral and the number of electrons
is equal to the number of protons
• A charge is shown if it is an ion.
80
35
Br
1–
Ionic charge
(1 extra electron)
Ions
• Many elements want to form stable
ions where the number of electrons
in the valence is the same as a
noble gas.
• Metals tend to become cations.
• Non metals tend to become anions.
• They become ions by gaining or
losing electrons (which ever is
easier).
Anions
1Cl
Cl
• Easier to gain 1 electron than lose 7.
• Therefore the atom becomes an anion by gaining an
electron.
• It becomes more stable by gaining an electron.
Cations
1+
Na
Na
• Easier to lose 1 electron than gain 7.
• Therefore the atom becomes a cation by losing an
electron.
• It becomes more stable by losing an electron.
Types of Bonding
• Bonds between atoms can be either
ionic or covalent
– An ionic bond is when an electron from
one atom is given to another atom and
they are held together by strong
electrostatic forces
– A covalent bond is when electrons are
shared between atoms to form a very
strong bond
Homework
• Read 5.5 and 5.6 in your textbook
(Science 10)
• Define words in bold
• P.184 Q.1-8
• P.189 Q.1-4
• Complete handout