EASIER STUDY GUIDE B for Chapter 6 RETEST 2/19
The atom (from a-tomos, which means not able to be
cut or divided) is the smallest particle that an element
can be reduced to.
ATOMIC DISCOVERIES
Dalton rediscovered the idea of the atom.
Dalton believed that:
o
Everything is made from atoms, which
was proven correct.
o
Atoms are small particles that cannot be
created, divided or destroyed, which was
proven false.
Dalton’s theory was changed in 1897 when
Thompson discovered the negatively charged
electron (like plums in the Plum Pudding model)
Rutherford discovered at the center of the
atom the positively charged nucleus which is
very small and dense, and that most of an atom
is empty space.
Bohr discovered the energy levels where he
thought the electrons moved in definite paths
like the orbits of planets in the solar system.
Schrödinger discovered electron clouds, a
more accurate idea of energy level areas around
the nucleus where electrons are most likely to
be found.
ATOMS
A dime has more atoms than Earth has people.
Every atom of a given element has the same
number of protons.
The number of protons in an atom, called the
atomic number, is found at the top of each small
square of the periodic table.
The mass number (the bottom number in a
square of the periodic table) is the total number
of protons and neutrons in an atom of that
element.
Electrons are not counted in the mass number
because they have the least mass (very tiny)
compared to protons and neutrons
ISOTOPES
Isotopes, like brothers and sisters of the same
element have the same number of protons, but
different numbers of neutrons, and therefore,
different mass numbers.
For example, there are three isotopes of
hydrogen, all of which have one proton.
In addition to the one proton,
o
Hydrogen-1, the most common form of
hydrogen has no neutrons.
o
The hydrogen-2 isotope, called deuterium
has one neutron.
o
The hydrogen-3 isotope has two neutrons.
Radioactive isotopes are unstable and produce
energy as they change.
EASIER STUDY GUIDE B for Chapter 7 RETEST 2/19
Chapter 7 ReTest 2-19 EASIER STUDY GUIDE
Periodic is a word used to describe something that
happens over and over at regular intervals.
The Periodic Law says that properties of elements
change periodically with the atomic numbers of the
elements.
All of the recently discovered elements follow
the periodic law
The Periodic Table of the Elements is arranged
Horizontally from left to right in order of
increasing atomic number (number of protons).
o
o
Each horizontal row is a “period”.
Originally, Mendeleev grouped the
elements in order of increasing atomic
mass instead of atomic number
Vertically in Groups or Families of elements
with:
o
Similar chemical and physical properties
o
Same number of valence electrons.
Similar types of elements are in particular places on
the periodic table:
Elements left of the zigzag line are metals.
o
Metals are shiny (luster)
o
Electrically and thermally(heat)
conductive
o
Malleable (can be bent) and Ductile (can
be made into wire)
o
Most of the elements on the periodic table
are metals.
The Elements to the right of the zigzag line are
nonmetals
o
o
o
o
They are easily shattered.
many are gases at room temperature,
including the noble gases.
They are dull.
They are not conductors of electric
current or heat.
Elements next to the zigzag line are semimetals or metalloids
o
They are semi-conductors, like silicon,
important for making computer chips.
LOOK UP THE PROPERTIES IN THE BOOK FOR
THE OTHER GROUPS AND KNOW THEM. For
example:
The alkali metals are
o
so soft that they can be cut with a knife
o
react violently with water.
o
very reactive.
When halogens (group 17) non metals react
with a metal, a salt is the new compound that is
formed through ionic bonds.
CHEMICAL SYMBOL
The chemical symbol is the abbreviation in
larger letters in each square of the periodic
table.
usually a single capital letter, sometimes with
another lower case letter
Oftentimes on periodic tables, the color of the
chemical symbol will tell you what the physical
state of an element is at room temperature
--Know how to find out which element has a given
number of protons (look for the atomic number, and
that is the element)
--Know where to find the metalloids.
--Nothing can burn unless it has oxygen, which makes
up about 20% of the air we breathe.
--Carbon comes in many forms, such as diamonds,
buckyballs, soot, graphite (pencil “lead”) and others.
--Sulfur is widely used in the chemical industry…can
you tell why?
Family
Name
Group
Number
Alkali
Metals
1
Alkaline
Earth
Metals
Transition
Metals
2
3-12
Boron
Group
13
Carbon
Group
14
Nitrogen
Group
15
Oxygen
Group
16
Halogens
17
Noble
(inert)
Gases
Hydrogen
18
Not in a
group
Calculate
Valence
Electrons
Same as
group
number
Same as
group
number
varies
Group
number
minus 10
Group
number
minus 10
Group
number
minus 10
Group
number
minus 10
Group
number
minus 10
Group
number
minus 10
# Valence
Electrons
1
2
varies
3
4
5
6
7
8
1