Download Atoms and the Periodic Table

ATOMS
AND THE
PERIODIC
TABLE
CHAPTER 3
PHYSICAL
SCIENCE
Chapter 3 Vocabulary Words (27 words)














Nucleus
Proton
Neutron
Electron
Energy level
Orbital
Valence electron
Periodic law
Period
Group
Ionization
Ion
Cation
Anion
Atomic number
Mass number
Isotopes
Atomic mass unit (amu)
Average atomic mass
Metals
Nonmetals
Semiconductors
Alkali metals
Alkaline-earth metals
Transition metals
Halogens
Noble gases
A. Atomic Structure
1.
What are atoms?
a.
b.
c.
Atoms are tiny units that determine properties
of all matter.
Democritus was the first to suggest that the
universe was made of atoms, but couldn’t
provide evidence to prove it!
1808 John Dalton proposed the atomic theory
with evidence to support it
1. John Dalton’s Atomic Theory
a.
b.
c.
Every element is
made of tiny, unique
particles called atoms
that cannot be
subdivided.
Atoms of the same
element are exactly
alike.
Atoms of different
elements can join to
form molecules.
2. What’s in an Atom?
a.
Atoms are made of
protons, neutrons, and
electrons
1.
2.
3.
4.
nucleus: the center of an
atom made up of protons
and neutrons
Protons: a positively
charged subatomic particle
in the nucleus of an atom
Neutron: a neutral
subatomic particle in the
nucleus of an atom
Electron: a tiny negatively
charged subatomic particle
moving around outside the
nucleus of an atom
5. The number of protons and electrons an atom has is
unique for each element.
b.
Atoms have no overall charge
1. Atoms don’t have a charge because they have
an equal number of protons and electrons whose
charges exactly cancel.
2. Example: Helium- 2 protons/2 electrons
3. Models of the Atom
a.
Bohr’s model compares electrons to planets
1.
2.
3.
1913 Niels Bohr suggested that electrons in an atom
move in set paths around the nucleus like the planets
around the sun.
Energy level: any of the possible energies an electron
may have in an atom
Electrons must gain or lose energy to move up or
down the energy levels
b. According to modern theory, electrons
behave more like waves
1.
2.
Since Bohr’s model couldn’t explain
everything, the modern model believes
electrons behave like waves on a vibrating
string.
Don’t exactly know where the electrons are at,
but can calculate an area they are found
3. Just like a fan blade moving
3. Electrons are found in orbitals within energy levels
4.
a. Orbitals: a region in an atom where there
is a high probability of finding electrons
b. There are four different kinds of orbitals
Every atom has one or more valence electrons
a. Valence electron: an electron in the
outermost energy level of an atom
B. A Guided Tour of the Periodic
Table
1.
Organization of the Periodic Table
a.
b.
c.
The periodic table groups similar elements together
The order is based on the number of protons an atom
of that element has in its nucleus
Periodic law: properties of elements tend to change in
a regular pattern when elements are arranged in order
of increasing atomic number, or number of protons in
their atoms.
4.
Using the periodic table to determine electronic
arrangement
a. Period: a horizontal row of elements in the
periodic table
b. Just as the number of protons increase left to
right, so does the number of electrons
5. Elements in the same group have similar properties
a. Group (family): a vertical column of elements
in the periodic table
b. Valence electrons determine properties
c. Atoms in the same group have the same
number of valence electrons
2. Some Atoms Form Ions
a.
b.
c.
d.
Atoms that do not have filled outermost energy
levels may undergo ionization.
Ionization: the process of adding electrons to
or removing electrons from an atom or group
of atoms
Atoms do this to fill their outermost energy
levels
Ion: an atom or group of atoms that has lost
or gained one or more electrons and therefore
has a net electric charge
e.
Cation: an ion with a positive charge
1. Caused by losing electrons
f.
Anion: an ion with a negative charge
1. Caused by gaining electrons
3. How do the Structures of Atoms Differ?
A.
Atomic number
equals the number of
protons
1. Atomic number: the
number of protons in
the nucleus of an atom
2. Each element has a
different number of
proton.
B. Mass number equals the total number of subatomic
particles in the nucleus
1. Mass number: the
total number of
protons and neutrons
in the nucleus of an
atom
C. Isotopes of an element have different number of
neutrons
1. Isotopes: any atoms having the same number
of protons but different numbers of neutrons
D. Some isotopes are
more common than
others
E. Calculating the number of neutrons in an atom
1.
Subtract atomic number from the mass
number
F. The mass of an atom
a.
b.
c.
Atomic mass unit
(amu): a quantity
equal to one-twelfth of
the mass of a carbon12 atom
Proton and neutron
have a mass of 1amu
Average atomic mass:
the weighted average
of masses of all
naturally occurring
isotopes of an element
1. Often found on the
periodic table
C.
1.
Families of Elements
How are Elements Classified?
a.
b.
c.
Elements are either metals or nonmetals
Metals: the elements that are good conductors of heat
and electricity
Nonmetals: the elements that are usually poor conductors
of heat and electricity
d. Semiconductors: the elements that are intermediate
conductors of heat and electricity
2. Metals
a.
Alkali Metals
1. Alkali metals: the
highly reactive metallic
elements located in
Group 1 of the periodic
table
b. Alkaline-earth metals
1. Alkaline-earth metals:
the reactive metallic
elements located in
Group 2 of the
periodic table
c. Transition metals
1. Transition metals:
the metallic elements
located in groups 3-12
of the periodic table
d. Synthetic elements
1. Man-made elements
3. Nonmetals
a.
b.
Found on the right
side of the periodic
table, except for
hydrogen
Carbon is found in
three different forms
and can also form
many compounds
c. Nonmetals and their compounds are plentiful on
Earth
d.
Chlorine is a halogen
that protects you
from harmful bacteria
1. halogen: the highly
reactive elements
located in Group 17 of
the periodic table
d. The noble gas neon is inert
1.
Noble gases: the
unreactive gaseous
elements located in
Group 18 of the
periodic table
e. Semiconductors are intermediate conductors of heat
and electricity
f. Silicon is the most
familiar semiconductor