Properties of Atoms and the Periodic Table
Section 1 Structure of the Atom
element Matter made from one type of atom
atom Smallest part of an element – nucleus contains most of its mass
nucleus Has a positive charge and made of protons and neutrons
proton S ubatomic partials with positive charge
neutron S ubatomic partials with no charge
electron S ubatomic partials with negative charge
quark S mallest property of atom, used to make protons & neutrons, total of
G roup of electrons rotating around nucleus
electron cloud 6
electron cloud
quarks
nucleus
atom
proton or
neutron
Timeline of the changes that have occurred in modeling the atomic structure since the 1800’s
Current Model
Properties of Atoms and the Periodic Table
Section 2 Masses of Atoms
mass
atomic number
mass number
isotope
average atomic mass
amount of matter in an object
a number equal to the number of protons in an atom’s nucleus
sum of the number of protons and neutrons in an atom
atoms of the same element with different numbers of neutrons
the average mass of the mixture of isotopes of an element
A. Nucleus of atom
contains most of the mass of an atom
masses of protons and neutrons in a nucleus are nearly identical
electron’s mass is so small it is not included in atomic mass
B. Atomic mass unit
amu appropriate unit for measuring the size of a particle
equals one-twelfth the mass of a carbon atom
each proton and each neutron has a mass of about 1 amu
C. Protons
number of protons is used to identify elements
each element has different number of protons
number of protons equals the atomic number of the element
number of electrons equals the number of protons in an element
D. Mass number
equals the sum of the number of protons plus neutrons of an atom
atoms of the same element can have different number of neutrons and a different mass number
Properties of Atoms and the Periodic Table
Section 3 The Periodic Table
chemical property
periodic table
period
group
electron dot diagram
Organizing the
Elements
any characteristic of a substance that indicates whether it can undergo a certain
chemical change
an arrangement of the elements by increasing atomic number and by changes in physical
and chemical properties
a horizontal row of elements on the periodic table
a vertical column of elements on the periodic table
the symbol of an element with dots representing the number of electrons in the outer
energy level
Compare Mendeleev’s early periodic table to that of today by
completing the Venn diagram.
Mendeleev
Today (Moseley)
Both
increasing
atomic mass
vertically
The Atom and the
Periodic Table
predict properties
of unknown
elements; allow
for future additions
repeating patterns
increasing
atomic number
horizontally
Sequence the energy levels in the electron cloud diagram and
write the maximum number of electrons that can be contained in
each level.
Level 4; 32
Level 3; 18
Level 2; 8
Level 1; 2
Nucleus; 0
Properties of Atoms and the Periodic Table
Section 3 The Periodic Table (contd)
Analyze how electron dot diagrams show similarities between
elements within a group.
Elements within a group all have the same electron dot diagrams, because they have the same number of
electrons in their outer energy levels. They are similar in how they combine with other elements to fill the
outermost level.
Classify the regions of the periodic table as metals, nonmetals, or metalloids.
Regions of the
Periodic Table
• Shade the regions on the blank periodic table.
• Label each region and write its characteristics.
Write a paragraph showing the relationship between chemistry and physics based on what you’ve
learned from the periodic table.
The chemical behavior of matter can be described in terms of energy and forces, both electrical
and magnetic. The structure of the atom is described in terms of energy levels. Reactivity
between atoms is described in terms of energy as well.
Wrap-Up
Now that you have read the chapter, think about what you have learned and complete the table below.
1. Write an A if you agree with the statement.
2. Write a D if you disagree with the statement.
Properties of Atoms and
the Periodic Table
After You
Read
• An atom is the smallest unit of an element that
still has all the properties of the element.
D
• An atom is made up of a positively charged
nucleus and negatively charged electrons.
A
• Quarks are so tiny that they orbit the nucleus
with the electrons.
D
• Isotopes of an element only differ in their
number of neutrons.
A
• An element’s chemical/physical properties may
be predicted by its location on the periodic table.
A