Standards 3.a. 7.b.
The Atom & Elements
Topic 1: Atoms and Matter
STANDARD 3.A.
Matter and Atoms
  Everything in the world and universe is
made of matter.
  Matter is anything that has mass and
takes up space.
  Matter can be broken down into
smaller parts called atoms.
  An atom is a very small particle that
makes up all matter.
Elements
  Not all things are made up of the same type of atoms.
  For example, gold and silver are two different types of
matter which are made up of different types of atoms.
  These different types of atoms are known as elements.
Think-Check
  What is an atom?
A.  A molecule of particles.
B.  An element of particles.
C.  A small particle that makes up matter.
Topic 2: Atomic Structure
STANDARD 3.A.
Parts of an Atom
  The atom itself can be broken down into smaller parts.
  The atom is made up of protons, neutrons, and electrons.
  Protons are positively charged particles.
  Neutrons are neutral particles.
  Electrons are negatively charged particles.
Atomic Structure
  An atom is mostly empty
space surrounding a tiny
nucleus.
  A nucleus is a region that
is located at the center of
an atom and contains
most of the atom’s mass.
  The nucleus contains
protons and neutrons.
Around the nucleus are
electrons.
Think-Check
  What type of particle
  What is the nucleus
is negatively charged?
A.  Electrons
B.  Protons
C.  Neutrons
composed of?
A.  Electrons and Neutrons
B.  Protons and Neutrons
C.  Protons and Electrons
Atomic Models
Bohr's Atomic Model
Electron Cloud Model
  Bohr’s model contains a
  The electron cloud model is
nucleus, which is composed of
protons and neutrons.
  Around the nucleus electrons
orbit definite diameters.
the model accepted by
scientists today.
  It also contains a nucleus of
protons and neutrons, but it is
impossible to tell where an
electron is around the nucleus
at any particular time.
Electron Motion
  The negatively
charged energy of an
electron keeps it in
motion around the
positively charged
nucleus to which it is
attracted.
Think-Check
  What is the structure
of an atom?
A.  A core of electrons and
neutrons surrounded by
protons.
B.  A core of protons and
neutrons surrounded by
electrons.
C.  A core of protons and
electrons surrounded
by neutrons.
  How are electrons able to
move around the nucleus?
A.  The negatively charged
electrons are attracted to the
positively charged nucleus.
B.  The negatively charged
electrons are attracted to the
negatively charged nucleus.
C.  The positively charged
electrons are attracted to the
negatively charged nucleus.
Topic 3: Elements
STANDARDS 7.B.
Elements
  An element is a pure substance made from atoms
that all have the same number of protons.
  Each element is represented by a symbol and has a
unique number of protons.
  The number of protons is known as the atomic
number.
Elements
  For example, Sodium (Na) has an atomic number of 11.
  This means that Sodium has 11 protons.
  No other elements will have 11 protons, because every
other element has a different atomic number.
Think-Check
  What makes an oxygen
element different from
calcium element?
A.  The atomic number
which gives the number
of neutrons.
B.  The atomic number
which gives the number
of protons.
C.  The atomic number
which gives the number
of electrons.
  Which element has 32
protons?
Elements
Atomic
Number
Atomic Mass
S
16
32
C
6
12
Ge
32
73
A.  Sulfur (S)
Carbon (C)
C.  Germanium (Ge)
B.
Topic 4: Isotopes
STANDARD 7.B.
Isotopes
  Atoms with different atomic numbers are atoms of
different elements. This means the number of
protons is always the same for a particular element.
  However, this is not always true for the number of
neutrons in the nucleus.
  Atoms of the same element that contain different
numbers of neutrons are called isotopes.
Isotopes & Atomic Mass
  The atomic mass minus the atomic
number (number of protons)
equals the number of neutrons.
  If the atomic mass changes then
the number of neutrons changes,
making different isotopes.
  For example, carbon can have an
atomic mass of 12, 13, or 14. The
number of protons (6) never
changes, but the number of
neutrons does change.
# of
Neutr
o ns =
Ato mi
c
Mass
– Ato
mic
Nu mb
er
Radioactivity
  Isotopes of an element differ based on the number of
neutrons in the nucleus.
  Sometimes the nucleus is unstable and undergoes
radioactive decay making the isotope radioactive.
  Radioactive decay occurs when an unstable atomic
nucleus changes into another nucleus by emitting one or
more particles of energy.
Think-Check
  What makes each
Carbon isotope
different?
  Using the data table
below, what isotope is
most likely radioactive?
Isotope
Atomic
Mass
C-12
12
C-13
13
C-14
14
The number of protons
B.  The number of neutrons
C.  The number of electrons
A.
Carbon 12
B.  Hydrogen 1
C.  Oxygen 18
A.