2. • WHAT IS AN ELEMENT?
• A substance composed of a single kind of atom.
• Cannot be broken down into another substance by chemical or
physical means.
•
3. • WHAT IS A MIXTURE?
• Two or more substances that are mixed
together but are not chemically bonded.
WHAT IS A COMPOUND?
• A substance in which two or more different elements are chemically
bonded together.
4. • WHAT IS PERIODIC
TABLE?
• A table in which the chemical
elements are arranged in order
of increasing atomic number.
• Elements with similar
properties are arranged in the
same column (called a group),
• Elements with the same
number of electron shells are
arranged in the same row
(called a period).
• OR
• Shows all known elements in
the universe.
• Organizes the elements by
chemical properties.
6. • WHAT IS ATOMIC NUMBER?
• The number of protons found in the
nucleus of an atom
• OR
• The number of electrons surrounding
the nucleus of an atom.
• WHAT IS THE SYMBOL?
• An abbreviation of the element name.
7. • WHAT IS THE ATOMIC WEIGHT?
• The number of protons and neutrons in the nucleus
of an atom.
HOW DO I FIND THE NUMBER OF PROTONS, ELECTRONS, AND
NEUTRONS IN AN ELEMENT USING THE PERIODIC TABLE?
• Number of PROTONS = ATOMIC NUMBER
• Number of ELECTRONS= ATOMIC NUMBER
• Number of NEUTRONS = ATOMIC WEIGHT - ATOMIC NUMBER
8. • THE BOHR MODEL OF THE ATOM
• The Bohr Model has an atom consisting of a small,
positively charged nucleus orbited by negatively
charged electrons.
• The Bohr Model, which is sometimes called the
Rutherford-Bohr Model.
9. Atoms are made of 3 subatomic particles:
1. Positive protons found in the nucleus of the atom; these determine the identify of the
atom and contribute to its mass
2. Neutral neutrons found in the nucleus of the atom; these determine the stability of the
atom and contribute to its mass
3. Negative electrons found in the electron cloud of the atom; these determine the charge on
the atom
• The outermost electrons are called valence electrons and determine the chemical properties
of the atom.
