Periodic Table
Periodic Table
• The periodic table is a chart containing information
about the atoms that make up all matter.
• It is called the periodic table of elements because
elements are made of the same kind of atom.
Periodic Table
• In the periodic table we can learn element’s
names, their atomic number, number of
protons, neutrons, and electrons, number of
valence electrons and atomic mass.
Element
• An element is a substance made up of only
one type of atom.
ATOMIC NUMBER
ELEMENT SYMBOL
ATOMIC MASS
ELEMENT NAME
Atomic Number
• The atomic number of an atom is equal to the
number of protons in its nucleus.
• How many protons to the following elements have?
a)
magnesium
b)
lead
c)
aluminum
Number of Electrons
• All neutral atoms have the same number electrons as protons. The
atomic number tells us the number of protons, and it also tells us the
total number of electrons.
• The number of electrons surrounding the nucleus of an atom is equal
to the number of protons in its nucleus.
• How many electrons do the following elements have?
a)
potassium
b)
sulfur
Atomic Mass
• The atomic mass tells us how much an atom weighs.
• Atomic mass is equal to the number of protons plus the
number of neutrons.
• Atomic mass is measured in “atomic mass units” (amu)
Demo
Atomic Mass
- Xenon
- atomic mass of
131.293 amu
- Protons + Neutrons
= 131.293 amu
Atomic Mass
•Xenon has an atomic mass of 131.293 amu
•To find the number of neutrons
1) We round the atomic mass:
131 amu
2) We subtract the atomic number from the atomic
mass:
131 – 54 = 77
-(atomic mass - # protons = # neutrons)
-(Big # – small # = # of neutrons)
Atomic Mass
• Using your Periodic Table of Elements find the
atomic mass of the following:
1) Nitrogen
2) Barium
3) Mercury
4) Argon
Number of Neutrons
• To find the number of neutrons:
1) We round the atomic mass:
2) We subtract the atomic number from the atomic mass:
(atomic mass - # protons = # neutrons)
• How many neutrons do the following atoms have? Show
your work!
a)
beryllium
b)
sodium
Finding Number of Neutrons Example
•Xenon has an atomic mass of 131.293 amu
•To find the number of neutrons
1) We round the atomic mass:
131 amu.
2) We subtract the atomic number from the atomic
mass:
131 – 54 = 77
-(atomic mass – # protons = # neutrons)
-(Big # – small # = # of neutrons)
Periods
• Periods are the horizontal rows in a periodic table.
• Periods tell us about how electrons sit around the
nucleus, depending upon the element.
• Write the period number beside each row.
Groups/Families
• Groups or families are the vertical columns in a periodic
table.
• All the elements in the same group have the same number
of valence electrons.
• All the elements in the same group have similar chemical
characteristics.
• Write the group number
that has the letter A beside
it for each group.
Valence Electrons
• Electrons have different orbits around the nucleus.
• Valence electrons are the electrons that are on the
outermost orbit.
• We can tell how many valence electrons an element has
based on which group it is in. Look at the groups with the
letter ‘A’ in them!
Valence Electrons
• How many valence
electrons do the
following elements
have?
1) Boron
2) Chlorine
3) Calcium
4) Cesium
5) Oxygen